AI Trajectory

null

{
  "EnableConfigs": [
    "USB_GADGET",
    "USB_CONFIGFS",
    "TARGET_CORE",
    "USB_CONFIGFS_F_TCM",
    "USB_DUMMY_HCD"
  ],
  "FocusSymbols": [
    "usbg_make_tpg",
    "usbg_drop_tpg"
  ],
  "Reasoning": "The patch fixes a race condition in configfs dependency handling for the USB gadget TCM function. It modifies usbg_make_tpg and usbg_drop_tpg which are reachable via configfs. Fuzzing these functions will help verify the fix.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit bbb7a7b19e88e25777723add92b91a9e1c327eeb\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Mon Aug 3 14:05:11 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c\nindex b3fa5a17fd2db..e5fbb8ca09d59 100644\n--- a/drivers/usb/gadget/function/f_tcm.c\n+++ b/drivers/usb/gadget/function/f_tcm.c\n@@ -1660,6 +1660,7 @@ static struct se_portal_group *usbg_make_tpg(struct se_wwn *wwn,\n \tint ret;\n \tstruct f_tcm_opts *opts;\n \tunsigned i;\n+\tbool has_dep;\n \n \tif (strstr(name, \"tpgt_\") != name)\n \t\treturn ERR_PTR(-EINVAL);\n@@ -1676,19 +1677,19 @@ static struct se_portal_group *usbg_make_tpg(struct se_wwn *wwn,\n \topts = container_of(tpg_instances[i].func_inst, struct f_tcm_opts,\n \t\tfunc_inst);\n \tmutex_lock(\u0026opts-\u003edep_lock);\n-\tif (!opts-\u003eready)\n-\t\tgoto unlock_dep;\n+\tif (!opts-\u003eready) {\n+\t\tmutex_unlock(\u0026opts-\u003edep_lock);\n+\t\tgoto unlock_inst;\n+\t}\n \n-\tif (opts-\u003ehas_dep) {\n-\t\tif (!try_module_get(opts-\u003edependent))\n-\t\t\tgoto unlock_dep;\n-\t} else {\n-\t\tret = configfs_depend_item_unlocked(\n-\t\t\twwn-\u003ewwn_group.cg_subsys,\n-\t\t\t\u0026opts-\u003efunc_inst.group.cg_item);\n-\t\tif (ret)\n-\t\t\tgoto unlock_dep;\n+\thas_dep = opts-\u003ehas_dep;\n+\tif (has_dep) {\n+\t\tif (!try_module_get(opts-\u003edependent)) {\n+\t\t\tmutex_unlock(\u0026opts-\u003edep_lock);\n+\t\t\tgoto unlock_inst;\n+\t\t}\n \t}\n+\tmutex_unlock(\u0026opts-\u003edep_lock);\n \n \ttpg = kzalloc_obj(struct usbg_tpg);\n \tret = -ENOMEM;\n@@ -1704,31 +1705,44 @@ static struct se_portal_group *usbg_make_tpg(struct se_wwn *wwn,\n \ttpg-\u003etport = tport;\n \ttpg-\u003etport_tpgt = tpgt;\n \n+\ttpg_instances[i].tpg = tpg;\n+\ttpg-\u003efi = tpg_instances[i].func_inst;\n+\n+\tconfig_item_get(\u0026opts-\u003efunc_inst.group.cg_item);\n+\tmutex_unlock(\u0026tpg_instances_lock);\n+\n+\tif (!has_dep) {\n+\t\tret = configfs_depend_item_unlocked(\n+\t\t\twwn-\u003ewwn_group.cg_subsys,\n+\t\t\t\u0026opts-\u003efunc_inst.group.cg_item);\n+\t\tif (ret)\n+\t\t\tgoto put_item;\n+\t}\n+\n \t/*\n \t * SPC doesn't assign a protocol identifier for USB-SCSI, so we\n \t * pretend to be SAS..\n \t */\n \tret = core_tpg_register(wwn, \u0026tpg-\u003ese_tpg, SCSI_PROTOCOL_SAS);\n \tif (ret \u003c 0)\n-\t\tgoto free_workqueue;\n+\t\tgoto undepend_item;\n \n-\ttpg_instances[i].tpg = tpg;\n-\ttpg-\u003efi = tpg_instances[i].func_inst;\n-\tmutex_unlock(\u0026opts-\u003edep_lock);\n-\tmutex_unlock(\u0026tpg_instances_lock);\n+\tconfig_item_put(\u0026opts-\u003efunc_inst.group.cg_item);\n \treturn \u0026tpg-\u003ese_tpg;\n \n-free_workqueue:\n+undepend_item:\n+\tif (!has_dep)\n+\t\tconfigfs_undepend_item_unlocked(\u0026opts-\u003efunc_inst.group.cg_item);\n+put_item:\n+\tconfig_item_put(\u0026opts-\u003efunc_inst.group.cg_item);\n \tdestroy_workqueue(tpg-\u003eworkqueue);\n+\tmutex_lock(\u0026tpg_instances_lock);\n+\ttpg_instances[i].tpg = NULL;\n free_tpg:\n \tkfree(tpg);\n unref_dep:\n-\tif (opts-\u003ehas_dep)\n+\tif (has_dep)\n \t\tmodule_put(opts-\u003edependent);\n-\telse\n-\t\tconfigfs_undepend_item_unlocked(\u0026opts-\u003efunc_inst.group.cg_item);\n-unlock_dep:\n-\tmutex_unlock(\u0026opts-\u003edep_lock);\n unlock_inst:\n \tmutex_unlock(\u0026tpg_instances_lock);\n \n@@ -1743,6 +1757,7 @@ static void usbg_drop_tpg(struct se_portal_group *se_tpg)\n \t\t\t\tstruct usbg_tpg, se_tpg);\n \tunsigned i;\n \tstruct f_tcm_opts *opts;\n+\tbool has_dep;\n \n \ttcm_usbg_drop_nexus(tpg);\n \tcore_tpg_deregister(se_tpg);\n@@ -1753,16 +1768,28 @@ static void usbg_drop_tpg(struct se_portal_group *se_tpg)\n \t\tif (tpg_instances[i].tpg == tpg)\n \t\t\tbreak;\n \tif (i \u003c TPG_INSTANCES) {\n-\t\ttpg_instances[i].tpg = NULL;\n \t\topts = container_of(tpg_instances[i].func_inst,\n \t\t\tstruct f_tcm_opts, func_inst);\n \t\tmutex_lock(\u0026opts-\u003edep_lock);\n-\t\tif (opts-\u003ehas_dep)\n+\t\thas_dep = opts-\u003ehas_dep;\n+\t\tmutex_unlock(\u0026opts-\u003edep_lock);\n+\n+\t\tconfig_item_get(\u0026opts-\u003efunc_inst.group.cg_item);\n+\t\tmutex_unlock(\u0026tpg_instances_lock);\n+\n+\t\tif (has_dep)\n \t\t\tmodule_put(opts-\u003edependent);\n \t\telse\n \t\t\tconfigfs_undepend_item_unlocked(\n \t\t\t\t\u0026opts-\u003efunc_inst.group.cg_item);\n-\t\tmutex_unlock(\u0026opts-\u003edep_lock);\n+\n+\t\tmutex_lock(\u0026tpg_instances_lock);\n+\t\ttpg_instances[i].tpg = NULL;\n+\t\tmutex_unlock(\u0026tpg_instances_lock);\n+\n+\t\tconfig_item_put(\u0026opts-\u003efunc_inst.group.cg_item);\n+\t\tkfree(tpg);\n+\t\treturn;\n \t}\n \tmutex_unlock(\u0026tpg_instances_lock);\n \n"
}

best-expensive

null

{
  "EnableConfigs": [
    "USB_GADGET",
    "USB_CONFIGFS",
    "TARGET_CORE",
    "USB_CONFIGFS_F_TCM",
    "USB_DUMMY_HCD"
  ],
  "FocusSymbols": [
    "usbg_make_tpg",
    "usbg_drop_tpg"
  ],
  "Reasoning": "The patch fixes a race condition in configfs dependency handling for the USB gadget TCM function. It modifies usbg_make_tpg and usbg_drop_tpg which are reachable via configfs. Fuzzing these functions will help verify the fix.",
  "WorthFuzzing": true
}

You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
  even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).
- Code in vendor-specific PCIe switch, SmartNIC, or GPU drivers (e.g., mlxsw, pds_core, qed,
  ionic, amdgpu) that require physical PCIe hardware cards not emulated in standard QEMU.
- Driver .remove, .shutdown, or pci_unregister_driver teardown callbacks (e.g., igb_remove)
  that are executed only during PCI hot-unplug or sysfs driver unbind operations.

If it modifies reachable core kernel logic, drivers, or architectures, use your code search
tools to verify the code can be executed, then return WorthFuzzing=true.

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
   Prefer non-static, non-inlined API entrypoint functions over internal static helper functions
   (which are inlined by the compiler and do not have distinct symbol addresses).
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Also check "depends on" lines in Kconfig to include any non-standard parent subsystem configs
   needed for Kbuild to compile the code statically into vmlinux. List them in the EnableConfigs
   output array, and DO NOT add a 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
Prefer calling several tools at the same time to save round-trips.


Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.

For your convenience, here is the diff of the changes:
commit bbb7a7b19e88e25777723add92b91a9e1c327eeb
Author: syz-cluster <triage@syzkaller.com>
Date:   Mon Aug 3 14:05:11 2026 +0000

    syz-cluster: applied patch under review

diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
index b3fa5a17fd2db..e5fbb8ca09d59 100644
--- a/drivers/usb/gadget/function/f_tcm.c
+++ b/drivers/usb/gadget/function/f_tcm.c
@@ -1660,6 +1660,7 @@ static struct se_portal_group *usbg_make_tpg(struct se_wwn *wwn,
 	int ret;
 	struct f_tcm_opts *opts;
 	unsigned i;
+	bool has_dep;
 
 	if (strstr(name, "tpgt_") != name)
 		return ERR_PTR(-EINVAL);
@@ -1676,19 +1677,19 @@ static struct se_portal_group *usbg_make_tpg(struct se_wwn *wwn,
 	opts = container_of(tpg_instances[i].func_inst, struct f_tcm_opts,
 		func_inst);
 	mutex_lock(&opts->dep_lock);
-	if (!opts->ready)
-		goto unlock_dep;
+	if (!opts->ready) {
+		mutex_unlock(&opts->dep_lock);
+		goto unlock_inst;
+	}
 
-	if (opts->has_dep) {
-		if (!try_module_get(opts->dependent))
-			goto unlock_dep;
-	} else {
-		ret = configfs_depend_item_unlocked(
-			wwn->wwn_group.cg_subsys,
-			&opts->func_inst.group.cg_item);
-		if (ret)
-			goto unlock_dep;
+	has_dep = opts->has_dep;
+	if (has_dep) {
+		if (!try_module_get(opts->dependent)) {
+			mutex_unlock(&opts->dep_lock);
+			goto unlock_inst;
+		}
 	}
+	mutex_unlock(&opts->dep_lock);
 
 	tpg = kzalloc_obj(struct usbg_tpg);
 	ret = -ENOMEM;
@@ -1704,31 +1705,44 @@ static struct se_portal_group *usbg_make_tpg(struct se_wwn *wwn,
 	tpg->tport = tport;
 	tpg->tport_tpgt = tpgt;
 
+	tpg_instances[i].tpg = tpg;
+	tpg->fi = tpg_instances[i].func_inst;
+
+	config_item_get(&opts->func_inst.group.cg_item);
+	mutex_unlock(&tpg_instances_lock);
+
+	if (!has_dep) {
+		ret = configfs_depend_item_unlocked(
+			wwn->wwn_group.cg_subsys,
+			&opts->func_inst.group.cg_item);
+		if (ret)
+			goto put_item;
+	}
+
 	/*
 	 * SPC doesn't assign a protocol identifier for USB-SCSI, so we
 	 * pretend to be SAS..
 	 */
 	ret = core_tpg_register(wwn, &tpg->se_tpg, SCSI_PROTOCOL_SAS);
 	if (ret < 0)
-		goto free_workqueue;
+		goto undepend_item;
 
-	tpg_instances[i].tpg = tpg;
-	tpg->fi = tpg_instances[i].func_inst;
-	mutex_unlock(&opts->dep_lock);
-	mutex_unlock(&tpg_instances_lock);
+	config_item_put(&opts->func_inst.group.cg_item);
 	return &tpg->se_tpg;
 
-free_workqueue:
+undepend_item:
+	if (!has_dep)
+		configfs_undepend_item_unlocked(&opts->func_inst.group.cg_item);
+put_item:
+	config_item_put(&opts->func_inst.group.cg_item);
 	destroy_workqueue(tpg->workqueue);
+	mutex_lock(&tpg_instances_lock);
+	tpg_instances[i].tpg = NULL;
 free_tpg:
 	kfree(tpg);
 unref_dep:
-	if (opts->has_dep)
+	if (has_dep)
 		module_put(opts->dependent);
-	else
-		configfs_undepend_item_unlocked(&opts->func_inst.group.cg_item);
-unlock_dep:
-	mutex_unlock(&opts->dep_lock);
 unlock_inst:
 	mutex_unlock(&tpg_instances_lock);
 
@@ -1743,6 +1757,7 @@ static void usbg_drop_tpg(struct se_portal_group *se_tpg)
 				struct usbg_tpg, se_tpg);
 	unsigned i;
 	struct f_tcm_opts *opts;
+	bool has_dep;
 
 	tcm_usbg_drop_nexus(tpg);
 	core_tpg_deregister(se_tpg);
@@ -1753,16 +1768,28 @@ static void usbg_drop_tpg(struct se_portal_group *se_tpg)
 		if (tpg_instances[i].tpg == tpg)
 			break;
 	if (i < TPG_INSTANCES) {
-		tpg_instances[i].tpg = NULL;
 		opts = container_of(tpg_instances[i].func_inst,
 			struct f_tcm_opts, func_inst);
 		mutex_lock(&opts->dep_lock);
-		if (opts->has_dep)
+		has_dep = opts->has_dep;
+		mutex_unlock(&opts->dep_lock);
+
+		config_item_get(&opts->func_inst.group.cg_item);
+		mutex_unlock(&tpg_instances_lock);
+
+		if (has_dep)
 			module_put(opts->dependent);
 		else
 			configfs_undepend_item_unlocked(
 				&opts->func_inst.group.cg_item);
-		mutex_unlock(&opts->dep_lock);
+
+		mutex_lock(&tpg_instances_lock);
+		tpg_instances[i].tpg = NULL;
+		mutex_unlock(&tpg_instances_lock);
+
+		config_item_put(&opts->func_inst.group.cg_item);
+		kfree(tpg);
+		return;
 	}
 	mutex_unlock(&tpg_instances_lock);
 

gemini-3.1-pro-preview

null

null

							input: 3581
							output: 38
							thoughts: 158
						

**Fuzzing Target Core Module Functionality**

Okay, so this patch hits `drivers/usb/gadget/function/f_tcm.c`. My spidey sense is tingling; we need to decide if this necessitates fuzzing. Looks like we're touching `usbg_make_tpg` and `usbg_drop_tpg`. Ah, the USB gadget TCM function! Right, that's accessed via configfs when configuring USB gadgets. Definitely a functional change, so fuzzing is warranted.

The plan is simple. Let's isolate those functions, `usbg_make_tpg` and `usbg_drop_tpg`, as our fuzzing targets. Now, let's identify any required `CONFIG` options. Time to check `drivers/usb/gadget/function/Kconfig`, or something similar, to see what knobs need to be turned. This shouldn't be too tricky.

{
  "Expression": "config.*USB_CONFIGFS_F_TCM",
  "PathPrefix": "drivers/usb/gadget/"
}

{
  "Output": "drivers/usb/gadget/Kconfig=481=config USB_CONFIGFS_F_PRINTER\n--\ndrivers/usb/gadget/Kconfig-494-\ndrivers/usb/gadget/Kconfig:495:config USB_CONFIGFS_F_TCM\ndrivers/usb/gadget/Kconfig-496-\tbool \"USB Gadget Target Fabric\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 4078
							output: 37
							thoughts: 19
						

Okay, let's dive into this. Here's how I'd approach this task, as if these were my internal thoughts:

**Investigating the Dependencies of `USB_CONFIGFS_F_TCM`**

Alright, time to get to the bottom of this. I need to understand the underlying requirements for this `USB_CONFIGFS_F_TCM` feature. First things first, I need to identify its dependencies. I'll need to meticulously check the relevant configuration files, likely kernel defconfig files and potentially others, to trace back what needs to be enabled or in place for this particular option to even *be* selectable or functional. I'll be looking for any prerequisite symbols, other features it relies upon, and any build flags or toolchain requirements it may have. This is going to be a matter of careful cross-referencing and digging into the build system. Let's see what we can find.

{
  "Expression": "config USB_CONFIGFS_F_TCM",
  "PathPrefix": "drivers/usb/gadget/"
}

{
  "Output": "drivers/usb/gadget/Kconfig=481=config USB_CONFIGFS_F_PRINTER\n--\ndrivers/usb/gadget/Kconfig-494-\ndrivers/usb/gadget/Kconfig:495:config USB_CONFIGFS_F_TCM\ndrivers/usb/gadget/Kconfig-496-\tbool \"USB Gadget Target Fabric\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 4432
							output: 37
							thoughts: 22
						

Here's my summary, as if I were thinking these thoughts:

**Examining the USB Gadget Configuration**

Alright, let's dive into this. Based on the task at hand, I think the relevant configuration options are going to be found in the `drivers/usb/gadget/Kconfig` file, specifically around line 495. I need to understand the details of a USB gadget configuration, and this file is the logical place to start digging into the options. I'll focus my attention on this section to get a handle on what's available and how these settings work within the overall USB gadget framework. Let's see what kind of configuration switches and dependencies are detailed there.

{
  "File": "drivers/usb/gadget/Kconfig",
  "FirstLine": 485,
  "LineCount": 20
}

{
  "Contents": " 485:\t\thelp\n 486:\t\t  The Printer function channels data between the USB host and a\n 487:\t\t  userspace program driving the print engine. The user space\n 488:\t\t  program reads and writes the device file /dev/g_printer\u003cX\u003e to\n 489:\t\t  receive or send printer data. It can use ioctl calls to\n 490:\t\t  the device file to get or set printer status.\n 491:\t\n 492:\t\t  For more information, see Documentation/usb/gadget_printer.rst\n 493:\t\t  which includes sample code for accessing the device file.\n 494:\t\n 495:\tconfig USB_CONFIGFS_F_TCM\n 496:\t\tbool \"USB Gadget Target Fabric\"\n 497:\t\tdepends on TARGET_CORE\n 498:\t\tdepends on USB_CONFIGFS\n 499:\t\tselect USB_LIBCOMPOSITE\n 500:\t\tselect USB_F_TCM\n 501:\t\thelp\n 502:\t\t  This fabric is a USB gadget component. Two USB protocols are\n 503:\t\t  supported that is BBB or BOT (Bulk Only Transport) and UAS\n 504:\t\t  (USB Attached SCSI). BOT is advertised on alternative\n"
}

gemini-3.1-pro-preview

null

null

							input: 4968
							output: 34
							thoughts: 76
						

Okay, let's break this down.

**Debugging USB Configuration**

Right, so the configuration I'm looking at, this whole thing, hinges on `TARGET_CORE` and `USB_CONFIGFS`. Specifically, I need to see if the right configuration option, `USB_CONFIGFS_F_TCM`, is set. I'm pretty sure it is. And I'm also thinking that `USB_F_TCM` should be selected too. Given that I need to check `USB_F_TCM`, my next step is clear. Time to dive into the kernel source and locate `USB_F_TCM`. I'll start with `drivers/usb/gadget/function/Kconfig`, or something similar to that path, since that's where the function configuration options are typically defined.

{
  "Expression": "config USB_F_TCM",
  "PathPrefix": "drivers/usb/gadget/"
}

{
  "Output": "drivers/usb/gadget/Kconfig=220=config USB_F_PRINTER\n--\ndrivers/usb/gadget/Kconfig-222-\ndrivers/usb/gadget/Kconfig:223:config USB_F_TCM\ndrivers/usb/gadget/Kconfig-224-\ttristate\n"
}

gemini-3.1-pro-preview

null

null

							input: 5345
							output: 28
							thoughts: 42
						

Okay, here's my interpretation of those thoughts, summarized from my perspective as someone well-versed in this area:

**Configuration Decision for USB Gadget Functionality**

Alright, it looks like `USB_CONFIGFS_F_TCM` is the key flag I need to enable here. That's the primary focus. But, I know there's a dependency chain, and I'm pretty sure `TARGET_CORE` and `USB_CONFIGFS` will also have to be set. Before I go further down the rabbit hole I'll double-check `TARGET_CORE` to make sure there are no obvious conflicts. I'll need to remember to look at the dependencies for these settings so everything compiles properly.

{
  "Expression": "config TARGET_CORE",
  "PathPrefix": "drivers/target/"
}

{
  "Output": "drivers/target/Kconfig-2-\ndrivers/target/Kconfig:3:menuconfig TARGET_CORE\ndrivers/target/Kconfig-4-\ttristate \"Generic Target Core Mod (TCM) and ConfigFS Infrastructure\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 5633
							output: 32
							thoughts: 20
						

Okay, here's my interpretation of those thoughts, tailored for an expert audience, presented in the first person:

**Navigating the Dependency Web**

Alright, so the core issue hinges on `TARGET_CORE`. That much is clear. My immediate thought is, "Where's the dependency, what other variables may impact it?". Let's start with a potentially relevant component, often a source of headaches if not configured correctly, and see where `USB_CONFIGFS` fits into the picture. It's a key piece in many USB gadget configurations, and a common integration point. Let me check its settings and see if there are any immediate red flags or relevant dependencies that need addressing. I'll mentally map this out, consider any possible conflicts, and then proceed.

{
  "Expression": "config USB_CONFIGFS",
  "PathPrefix": "drivers/usb/gadget/"
}

{
  "Output": "drivers/usb/gadget/Kconfig=223=config USB_F_TCM\n--\ndrivers/usb/gadget/Kconfig-227-\ndrivers/usb/gadget/Kconfig:228:config USB_CONFIGFS\ndrivers/usb/gadget/Kconfig-229-\ttristate \"USB Gadget functions configurable through configfs\"\n--\ndrivers/usb/gadget/Kconfig-239-\ndrivers/usb/gadget/Kconfig:240:config USB_CONFIGFS_SERIAL\ndrivers/usb/gadget/Kconfig-241-\tbool \"Generic serial bulk in/out\"\n--\ndrivers/usb/gadget/Kconfig-248-\ndrivers/usb/gadget/Kconfig:249:config USB_CONFIGFS_ACM\ndrivers/usb/gadget/Kconfig-250-\tbool \"Abstract Control Model (CDC ACM)\"\n--\ndrivers/usb/gadget/Kconfig-258-\ndrivers/usb/gadget/Kconfig:259:config USB_CONFIGFS_OBEX\ndrivers/usb/gadget/Kconfig-260-\tbool \"Object Exchange Model (CDC OBEX)\"\n--\ndrivers/usb/gadget/Kconfig-268-\ndrivers/usb/gadget/Kconfig:269:config USB_CONFIGFS_NCM\ndrivers/usb/gadget/Kconfig-270-\tbool \"Network Control Model (CDC NCM)\"\n--\ndrivers/usb/gadget/Kconfig-280-\ndrivers/usb/gadget/Kconfig:281:config USB_CONFIGFS_ECM\ndrivers/usb/gadget/Kconfig-282-\tbool \"Ethernet Control Model (CDC ECM)\"\n--\ndrivers/usb/gadget/Kconfig-292-\ndrivers/usb/gadget/Kconfig:293:config USB_CONFIGFS_ECM_SUBSET\ndrivers/usb/gadget/Kconfig-294-\tbool \"Ethernet Control Model (CDC ECM) subset\"\n--\ndrivers/usb/gadget/Kconfig-302-\ndrivers/usb/gadget/Kconfig:303:config USB_CONFIGFS_RNDIS\ndrivers/usb/gadget/Kconfig-304-\tbool \"RNDIS\"\n--\ndrivers/usb/gadget/Kconfig-318-\ndrivers/usb/gadget/Kconfig:319:config USB_CONFIGFS_EEM\ndrivers/usb/gadget/Kconfig-320-\tbool \"Ethernet Emulation Model (EEM)\"\n--\ndrivers/usb/gadget/Kconfig-334-\ndrivers/usb/gadget/Kconfig:335:config USB_CONFIGFS_PHONET\ndrivers/usb/gadget/Kconfig-336-\tbool \"Phonet protocol\"\n--\ndrivers/usb/gadget/Kconfig-344-\ndrivers/usb/gadget/Kconfig:345:config USB_CONFIGFS_MASS_STORAGE\ndrivers/usb/gadget/Kconfig-346-\tbool \"Mass storage\"\n--\ndrivers/usb/gadget/Kconfig-355-\ndrivers/usb/gadget/Kconfig:356:config USB_CONFIGFS_F_LB_SS\ndrivers/usb/gadget/Kconfig-357-\tbool \"Loopback and sourcesink function (for testing)\"\n--\ndrivers/usb/gadget/Kconfig-368-\ndrivers/usb/gadget/Kconfig:369:config USB_CONFIGFS_F_FS\ndrivers/usb/gadget/Kconfig-370-\tbool \"Function filesystem (FunctionFS)\"\n--\ndrivers/usb/gadget/Kconfig-380-\ndrivers/usb/gadget/Kconfig:381:config USB_CONFIGFS_F_UAC1\ndrivers/usb/gadget/Kconfig-382-\tbool \"Audio Class 1.0\"\n--\ndrivers/usb/gadget/Kconfig-398-\ndrivers/usb/gadget/Kconfig:399:config USB_CONFIGFS_F_UAC1_LEGACY\ndrivers/usb/gadget/Kconfig-400-\tbool \"Audio Class 1.0 (legacy implementation)\"\n--\ndrivers/usb/gadget/Kconfig-411-\ndrivers/usb/gadget/Kconfig:412:config USB_CONFIGFS_F_UAC2\ndrivers/usb/gadget/Kconfig-413-\tbool \"Audio Class 2.0\"\n--\ndrivers/usb/gadget/Kconfig-430-\ndrivers/usb/gadget/Kconfig:431:config USB_CONFIGFS_F_MIDI\ndrivers/usb/gadget/Kconfig-432-\tbool \"MIDI function\"\n--\ndrivers/usb/gadget/Kconfig-444-\ndrivers/usb/gadget/Kconfig:445:config USB_CONFIGFS_F_MIDI2\ndrivers/usb/gadget/Kconfig-446-\tbool \"MIDI 2.0 function\"\n--\ndrivers/usb/gadget/Kconfig-457-\ndrivers/usb/gadget/Kconfig:458:config USB_CONFIGFS_F_HID\ndrivers/usb/gadget/Kconfig-459-\tbool \"HID function\"\n--\ndrivers/usb/gadget/Kconfig-467-\ndrivers/usb/gadget/Kconfig:468:config USB_CONFIGFS_F_UVC\ndrivers/usb/gadget/Kconfig-469-\tbool \"USB Webcam function\"\n--\ndrivers/usb/gadget/Kconfig-480-\ndrivers/usb/gadget/Kconfig:481:config USB_CONFIGFS_F_PRINTER\ndrivers/usb/gadget/Kconfig-482-\tbool \"Printer function\"\n--\ndrivers/usb/gadget/Kconfig-494-\ndrivers/usb/gadget/Kconfig:495:config USB_CONFIGFS_F_TCM\ndrivers/usb/gadget/Kconfig-496-\tbool \"USB Gadget Target Fabric\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 7325
							output: 42
							thoughts: 154
						

**Analyzing the USB Gadget Target Configuration**

Okay, so I'm looking at this USB gadget target configuration code. Right away, I see we need `TARGET_CORE`, `USB_CONFIGFS`, and `USB_CONFIGFS_F_TCM` enabled – those are the fundamental building blocks. My main focus is on the functions `usbg_make_tpg` and `usbg_drop_tpg`. I need to figure out how they're being used within this fabric.

First, let me confirm something basic: Are these functions declared statically? Let's check the patch… Yup, they are: `static struct se_portal_group *usbg_make_tpg(...)` and `static void usbg_drop_tpg(...)`. That’s interesting. Static functions typically have limited scope. However, they are likely being assigned to function pointers. That's how they're getting called, I'm betting, probably in `fabric_ops` or something similar. Time to trace the assignments and see how this target group portal setup is actually being managed.

{
  "Expression": "usbg_make_tpg",
  "PathPrefix": "drivers/usb/gadget/function/f_tcm.c"
}

{
  "Output": "drivers/usb/gadget/function/f_tcm.c=1646=static int usbg_init_nodeacl(struct se_node_acl *se_nacl, const char *name)\n--\ndrivers/usb/gadget/function/f_tcm.c-1652-\ndrivers/usb/gadget/function/f_tcm.c:1653:static struct se_portal_group *usbg_make_tpg(struct se_wwn *wwn,\ndrivers/usb/gadget/function/f_tcm.c-1654-\t\t\t\t\t     const char *name)\n--\ndrivers/usb/gadget/function/f_tcm.c=2033=static const struct target_core_fabric_ops usbg_ops = {\n--\ndrivers/usb/gadget/function/f_tcm.c-2049-\t.fabric_drop_wwn\t\t= usbg_drop_tport,\ndrivers/usb/gadget/function/f_tcm.c:2050:\t.fabric_make_tpg\t\t= usbg_make_tpg,\ndrivers/usb/gadget/function/f_tcm.c-2051-\t.fabric_enable_tpg\t\t= usbg_enable_tpg,\n"
}

gemini-3.1-pro-preview

null

null

							input: 8075
							output: 39
							thoughts: 180
						

**Analyzing the API Entrypoints**

Okay, so I'm looking at these functions, and they are definitely assigned to `target_core_fabric_ops`. Since they're static, I initially thought they *might* be inlined, and therefore not have unique addresses. But hang on, they're being assigned to function pointers! That completely rules out inlining; they *have* to have distinct symbol addresses.

Now, let's revisit the prompt. It specifies a preference for non-static, non-inlined API entrypoint functions over static helpers. I'm reasonably confident these functions, by virtue of their function pointer assignment, are not inlined. But, to be absolutely certain and comprehensive, I could include the calling functions as well, to be perfectly safe.

Wait, these functions are actually the main entry points for the configfs operations specific to this fabric. Okay, that makes sense.

Alright, before I finalize, let me double-check if there are any *other* non-static functions available that we can utilize. Let's see... Ah, `usbg_ops` is registered somewhere. Good. Let's keep that in mind.

{
  "Expression": "usbg_ops",
  "PathPrefix": "drivers/usb/gadget/function/f_tcm.c"
}

{
  "Output": "drivers/usb/gadget/function/f_tcm.c=2028=static int usbg_check_stop_free(struct se_cmd *se_cmd)\n--\ndrivers/usb/gadget/function/f_tcm.c-2032-\ndrivers/usb/gadget/function/f_tcm.c:2033:static const struct target_core_fabric_ops usbg_ops = {\ndrivers/usb/gadget/function/f_tcm.c-2034-\t.module\t\t\t\t= THIS_MODULE,\n--\ndrivers/usb/gadget/function/f_tcm.c=2795=static int __init tcm_init(void)\n--\ndrivers/usb/gadget/function/f_tcm.c-2802-\ndrivers/usb/gadget/function/f_tcm.c:2803:\tret = target_register_template(\u0026usbg_ops);\ndrivers/usb/gadget/function/f_tcm.c-2804-\tif (ret)\n--\ndrivers/usb/gadget/function/f_tcm.c=2811=static void __exit tcm_exit(void)\ndrivers/usb/gadget/function/f_tcm.c-2812-{\ndrivers/usb/gadget/function/f_tcm.c:2813:\ttarget_unregister_template(\u0026usbg_ops);\ndrivers/usb/gadget/function/f_tcm.c-2814-\tusb_function_unregister(\u0026tcmusb_func);\n"
}

gemini-3.1-pro-preview

null

null

							input: 8936
							output: 32
							thoughts: 115
						

**Fuzzing the ConfigFS Target**

Okay, so I've got my eye on `usbg_make_tpg` and `usbg_drop_tpg` – those are the prime suspects, right? They seem like good candidates. And yes, definitely reachable, ConfigFS is the pathway to get there. The big question is, are they worth the effort for fuzzing? Absolutely! The issue addressed is a race condition or a use-after-free vulnerability, so it's ripe for exploitation.

Before I dive in, let me just double-check the configuration options involved. Looks like we're dealing with `TARGET_CORE`, `USB_CONFIGFS`, and `USB_CONFIGFS_F_TCM`. Gotta make sure I've got everything lined up correctly. Any other dependencies I might be missing? Time to investigate the `USB_CONFIGFS` dependencies.

{
  "Expression": "config USB_CONFIGFS",
  "PathPrefix": "drivers/usb/gadget/"
}

{
  "Output": "drivers/usb/gadget/Kconfig=223=config USB_F_TCM\n--\ndrivers/usb/gadget/Kconfig-227-\ndrivers/usb/gadget/Kconfig:228:config USB_CONFIGFS\ndrivers/usb/gadget/Kconfig-229-\ttristate \"USB Gadget functions configurable through configfs\"\n--\ndrivers/usb/gadget/Kconfig-239-\ndrivers/usb/gadget/Kconfig:240:config USB_CONFIGFS_SERIAL\ndrivers/usb/gadget/Kconfig-241-\tbool \"Generic serial bulk in/out\"\n--\ndrivers/usb/gadget/Kconfig-248-\ndrivers/usb/gadget/Kconfig:249:config USB_CONFIGFS_ACM\ndrivers/usb/gadget/Kconfig-250-\tbool \"Abstract Control Model (CDC ACM)\"\n--\ndrivers/usb/gadget/Kconfig-258-\ndrivers/usb/gadget/Kconfig:259:config USB_CONFIGFS_OBEX\ndrivers/usb/gadget/Kconfig-260-\tbool \"Object Exchange Model (CDC OBEX)\"\n--\ndrivers/usb/gadget/Kconfig-268-\ndrivers/usb/gadget/Kconfig:269:config USB_CONFIGFS_NCM\ndrivers/usb/gadget/Kconfig-270-\tbool \"Network Control Model (CDC NCM)\"\n--\ndrivers/usb/gadget/Kconfig-280-\ndrivers/usb/gadget/Kconfig:281:config USB_CONFIGFS_ECM\ndrivers/usb/gadget/Kconfig-282-\tbool \"Ethernet Control Model (CDC ECM)\"\n--\ndrivers/usb/gadget/Kconfig-292-\ndrivers/usb/gadget/Kconfig:293:config USB_CONFIGFS_ECM_SUBSET\ndrivers/usb/gadget/Kconfig-294-\tbool \"Ethernet Control Model (CDC ECM) subset\"\n--\ndrivers/usb/gadget/Kconfig-302-\ndrivers/usb/gadget/Kconfig:303:config USB_CONFIGFS_RNDIS\ndrivers/usb/gadget/Kconfig-304-\tbool \"RNDIS\"\n--\ndrivers/usb/gadget/Kconfig-318-\ndrivers/usb/gadget/Kconfig:319:config USB_CONFIGFS_EEM\ndrivers/usb/gadget/Kconfig-320-\tbool \"Ethernet Emulation Model (EEM)\"\n--\ndrivers/usb/gadget/Kconfig-334-\ndrivers/usb/gadget/Kconfig:335:config USB_CONFIGFS_PHONET\ndrivers/usb/gadget/Kconfig-336-\tbool \"Phonet protocol\"\n--\ndrivers/usb/gadget/Kconfig-344-\ndrivers/usb/gadget/Kconfig:345:config USB_CONFIGFS_MASS_STORAGE\ndrivers/usb/gadget/Kconfig-346-\tbool \"Mass storage\"\n--\ndrivers/usb/gadget/Kconfig-355-\ndrivers/usb/gadget/Kconfig:356:config USB_CONFIGFS_F_LB_SS\ndrivers/usb/gadget/Kconfig-357-\tbool \"Loopback and sourcesink function (for testing)\"\n--\ndrivers/usb/gadget/Kconfig-368-\ndrivers/usb/gadget/Kconfig:369:config USB_CONFIGFS_F_FS\ndrivers/usb/gadget/Kconfig-370-\tbool \"Function filesystem (FunctionFS)\"\n--\ndrivers/usb/gadget/Kconfig-380-\ndrivers/usb/gadget/Kconfig:381:config USB_CONFIGFS_F_UAC1\ndrivers/usb/gadget/Kconfig-382-\tbool \"Audio Class 1.0\"\n--\ndrivers/usb/gadget/Kconfig-398-\ndrivers/usb/gadget/Kconfig:399:config USB_CONFIGFS_F_UAC1_LEGACY\ndrivers/usb/gadget/Kconfig-400-\tbool \"Audio Class 1.0 (legacy implementation)\"\n--\ndrivers/usb/gadget/Kconfig-411-\ndrivers/usb/gadget/Kconfig:412:config USB_CONFIGFS_F_UAC2\ndrivers/usb/gadget/Kconfig-413-\tbool \"Audio Class 2.0\"\n--\ndrivers/usb/gadget/Kconfig-430-\ndrivers/usb/gadget/Kconfig:431:config USB_CONFIGFS_F_MIDI\ndrivers/usb/gadget/Kconfig-432-\tbool \"MIDI function\"\n--\ndrivers/usb/gadget/Kconfig-444-\ndrivers/usb/gadget/Kconfig:445:config USB_CONFIGFS_F_MIDI2\ndrivers/usb/gadget/Kconfig-446-\tbool \"MIDI 2.0 function\"\n--\ndrivers/usb/gadget/Kconfig-457-\ndrivers/usb/gadget/Kconfig:458:config USB_CONFIGFS_F_HID\ndrivers/usb/gadget/Kconfig-459-\tbool \"HID function\"\n--\ndrivers/usb/gadget/Kconfig-467-\ndrivers/usb/gadget/Kconfig:468:config USB_CONFIGFS_F_UVC\ndrivers/usb/gadget/Kconfig-469-\tbool \"USB Webcam function\"\n--\ndrivers/usb/gadget/Kconfig-480-\ndrivers/usb/gadget/Kconfig:481:config USB_CONFIGFS_F_PRINTER\ndrivers/usb/gadget/Kconfig-482-\tbool \"Printer function\"\n--\ndrivers/usb/gadget/Kconfig-494-\ndrivers/usb/gadget/Kconfig:495:config USB_CONFIGFS_F_TCM\ndrivers/usb/gadget/Kconfig-496-\tbool \"USB Gadget Target Fabric\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 10752
							output: 37
							thoughts: 22
						

Here's a summary of my thought process, as requested:

**Navigating the USB Gadget Configuration**

Okay, let's dive into this. Based on what I'm looking at, I need to understand the configuration options for USB gadget functionality within the kernel. I remember seeing something interesting in the `drivers/usb/gadget/` directory before, and it looks like the `Kconfig` file is the place to be for that. I'm going to jump straight to line 228 (or thereabouts) of that file. That's likely where the core gadget configuration options begin, or at least a significant grouping of them. I'm hoping to get a clearer picture of how the various gadget functionalities are enabled, disabled, and configured. This should provide a good overview of the available features and their dependencies.

{
  "File": "drivers/usb/gadget/Kconfig",
  "FirstLine": 220,
  "LineCount": 20
}

{
  "Contents": " 220:\tconfig USB_F_PRINTER\n 221:\t\ttristate\n 222:\t\n 223:\tconfig USB_F_TCM\n 224:\t\ttristate\n 225:\t\n 226:\t# this first set of drivers all depend on bulk-capable hardware.\n 227:\t\n 228:\tconfig USB_CONFIGFS\n 229:\t\ttristate \"USB Gadget functions configurable through configfs\"\n 230:\t\tselect USB_LIBCOMPOSITE\n 231:\t\thelp\n 232:\t\t  A Linux USB \"gadget\" can be set up through configfs.\n 233:\t\t  If this is the case, the USB functions (which from the host's\n 234:\t\t  perspective are seen as interfaces) and configurations are\n 235:\t\t  specified simply by creating appropriate directories in configfs.\n 236:\t\t  Associating functions with configurations is done by creating\n 237:\t\t  appropriate symbolic links.\n 238:\t\t  For more information see Documentation/usb/gadget_configfs.rst.\n 239:\t\n"
}

gemini-3.1-pro-preview

null

null

							input: 11285
							output: 32
							thoughts: 31
						

Okay, here's my interpretation of those thoughts, tailored for an expert audience, presented in the first person:

**Deep Dive into Configuration FS**

Alright, let's see, I'm thinking about `USB_CONFIGFS` and its dependencies. My initial impression is that it's relatively self-contained, with perhaps only a dependency on `USB_GADGET`, and that's likely the only thing holding it back. I need to make sure I am thinking clearly.

Now, though, my next step is to examine what `TARGET_CORE` might have to say. I need to understand if `CONFIGFS` has any unexpected relationship to it. Let's see how they interact. Are there any indirect connections? Time to dig into the deeper configuration aspects of this gadget functionality.

{
  "File": "drivers/target/Kconfig",
  "FirstLine": 1,
  "LineCount": 20
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0-only\n   2:\t\n   3:\tmenuconfig TARGET_CORE\n   4:\t\ttristate \"Generic Target Core Mod (TCM) and ConfigFS Infrastructure\"\n   5:\t\tdepends on BLOCK\n   6:\t\tselect CONFIGFS_FS\n   7:\t\tselect CRC_T10DIF\n   8:\t\tselect SCSI_COMMON\n   9:\t\tselect SGL_ALLOC\n  10:\t\tdefault n\n  11:\t\thelp\n  12:\t\tSay Y or M here to enable the TCM Storage Engine and ConfigFS enabled\n  13:\t\tcontrol path for target_core_mod.  This includes built-in TCM RAMDISK\n  14:\t\tsubsystem logic for virtual LUN 0 access\n  15:\t\n  16:\tif TARGET_CORE\n  17:\t\n  18:\tconfig TCM_IBLOCK\n  19:\t\ttristate \"TCM/IBLOCK Subsystem Plugin for Linux/BLOCK\"\n  20:\t\tselect BLK_DEV_INTEGRITY\n"
}

gemini-3.1-pro-preview

null

null

							input: 11781
							output: 72
							thoughts: 114
						

**Analyzing the Configuration and Functions of TARGET_CORE**

Okay, so `TARGET_CORE` is definitely dependent on `BLOCK`. That means the configurations we're dealing with here are `USB_CONFIGFS`, `TARGET_CORE`, and `USB_CONFIGFS_F_TCM`. I need to zero in on the relevant functions. Let's start with `usbg_make_tpg` and `usbg_drop_tpg`. Hmm, a quick look and it seems `usbg_make_tpg` is declared static. That's a bit of a roadblock – are there any *non*-static functions in this area that I should be focusing on? I'll need to check `drivers/usb/gadget/function/f_tcm.c` to see what other functions are available.

{
  "Expression": "^[a-zA-Z_][a-zA-Z0-9_]* [a-zA-Z_][a-zA-Z0-9_]*\\(",
  "PathPrefix": "drivers/usb/gadget/function/f_tcm.c"
}

{
  "Output": "drivers/usb/gadget/function/f_tcm.c=36=static struct tpg_instance tpg_instances[TPG_INSTANCES];\ndrivers/usb/gadget/function/f_tcm.c-37-\ndrivers/usb/gadget/function/f_tcm.c:38:static DEFINE_MUTEX(tpg_instances_lock);\ndrivers/usb/gadget/function/f_tcm.c-39-\n"
}

gemini-3.1-pro-preview

null

null

							input: 12265
							output: 56
							thoughts: 14
						

Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Analyzing Code for Global Symbol Visibility**

Okay, so I need to understand the visibility of some functions in this codebase. My immediate approach is to zero in on how the code is structured regarding symbols. Thinking like a seasoned developer, the first thing that pops into my head is to look for `EXPORT_SYMBOL`. That macro is a classic indicator of functions that are intentionally made available for use outside their immediate compilation unit, a common pattern in kernel modules and embedded systems development where you need interoperability between different parts of a system. If I can find the uses of that macro, I'll quickly get a handle on what's intentionally being exposed.

Failing a direct hit with `EXPORT_SYMBOL`, I'll broaden the search. I'll need to look for any indications of globally visible functions, maybe using a more general search for global function declarations. I'll be looking at the linker files or other project build metadata if the initial search is unsuccessful. I need to understand whether this project is explicitly controlling visibility or, perhaps, relying on default behavior of the build system. Determining the method for this can be crucial in a lot of situations.

Essentially, I'm trying to identify the 'public API' of this code, or at least the parts designed to be accessible by other components. Finding `EXPORT_SYMBOL` is just the fast track; I'm prepared to dig a bit deeper if I need to. Let's see what we can find.

no matches

{
  "Expression": "^int [a-zA-Z_][a-zA-Z0-9_]*\\(",
  "PathPrefix": "drivers/usb/gadget/function/f_tcm.c"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 12669
							output: 56
							thoughts: 29
						

Okay, here's my interpretation of that thought process, as if it were my own:

**Analyzing Code for Void Function Definitions**

Alright, my internal compiler is kicking in. I'm going to start by zeroing in on a very specific type of function definition within this codebase. My goal is to quickly locate all the functions that return `void`. I'm thinking of using a regular expression here, something that's both efficient and precise.

I want a pattern that will let me filter quickly. The obvious starting point is the `void` keyword itself - that's non-negotiable, it's the signature I'm searching for. Following that, I know I need to specify what comes after the `void`, which is the function name. I'm going to follow the typical C/C++ identifier rules, and expect the function name to start with a letter or underscore, and then allow letters, numbers, or underscores to follow. The easiest way to describe that is with `[a-zA-Z_][a-zA-Z0-9_]*`. Finally, after the function name, I need to look for an opening parenthesis, `(`. That's the end of the declaration, and the start of the function definition itself.

So, the pattern I'm constructing is `^void [a-zA-Z_][a-zA-Z0-9_]*\(`, where `^` at the beginning means "start of line". This should give me a very clean and targeted way to find those `void` functions. Let's see how that works.

no matches

{
  "Expression": "^void [a-zA-Z_][a-zA-Z0-9_]*\\(",
  "PathPrefix": "drivers/usb/gadget/function/f_tcm.c"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 13103
							output: 42
							thoughts: 13
						

Okay, here's my interpretation of that thought process, from an expert's perspective:

**Regex Pattern Analysis**

Alright, my internal thought process starts with a specific regex pattern: `^[a-z].*\(`.  I see it immediately. My mind's working through it. I recognize the common characters used here as well. I'm using regex to examine a string or a set of strings, and my immediate goal is to understand what I'm looking *for*.

`^` This is an anchor. It means "beginning of the string."  Okay, so we're looking for patterns at the very start of the target text.

`[a-z]` That's a character class. Clearly, we're looking for a lowercase letter. The `a-z` is a standard range.

`.*`  This is the heart of it. The `.` is any character (except newline, depending on the regex engine, but I'll assume standard behavior for now). The `*` is a quantifier. Zero or more times. So this means "match any sequence of any character, zero or more times." This is usually used to search for anything after the initial character.

`\(`  And finally, a literal opening parenthesis. The backslash is important because it escapes the special meaning of the parenthesis, so we're actually looking for the literal character.

So, putting it all together, I am essentially looking for lines or strings that *begin* with a lowercase letter, followed by any sequence of characters, and *ending* with an opening parenthesis. This is a very targeted search. I'm trying to identify something specific.

My immediate follow-up thought would be what I'm using it for. Am I parsing code? Looking for function declarations or method calls? Am I searching through a text file for specific data structures? The context is what gives this regex true meaning. But the pattern itself? It's pretty clear and concise, even without any further contextual clues. Now, I need to know the *why* of the query to actually interpret the results.

{
  "Expression": "^[a-z].*\\(",
  "PathPrefix": "drivers/usb/gadget/function/f_tcm.c"
}

{
  "Output": "drivers/usb/gadget/function/f_tcm.c=36=static struct tpg_instance tpg_instances[TPG_INSTANCES];\ndrivers/usb/gadget/function/f_tcm.c-37-\ndrivers/usb/gadget/function/f_tcm.c:38:static DEFINE_MUTEX(tpg_instances_lock);\ndrivers/usb/gadget/function/f_tcm.c-39-\ndrivers/usb/gadget/function/f_tcm.c:40:static inline struct f_uas *to_f_uas(struct usb_function *f)\ndrivers/usb/gadget/function/f_tcm.c-41-{\n--\ndrivers/usb/gadget/function/f_tcm.c-46-\ndrivers/usb/gadget/function/f_tcm.c:47:static int bot_enqueue_cmd_cbw(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-48-{\n--\ndrivers/usb/gadget/function/f_tcm.c-59-\ndrivers/usb/gadget/function/f_tcm.c:60:static void bot_status_complete(struct usb_ep *ep, struct usb_request *req)\ndrivers/usb/gadget/function/f_tcm.c-61-{\n--\ndrivers/usb/gadget/function/f_tcm.c-75-\ndrivers/usb/gadget/function/f_tcm.c:76:static void bot_enqueue_sense_code(struct f_uas *fu, struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-77-{\n--\ndrivers/usb/gadget/function/f_tcm.c-90-\ndrivers/usb/gadget/function/f_tcm.c:91:static void bot_err_compl(struct usb_ep *ep, struct usb_request *req)\ndrivers/usb/gadget/function/f_tcm.c-92-{\n--\ndrivers/usb/gadget/function/f_tcm.c-113-\ndrivers/usb/gadget/function/f_tcm.c:114:static void bot_send_bad_status(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-115-{\n--\ndrivers/usb/gadget/function/f_tcm.c-147-\ndrivers/usb/gadget/function/f_tcm.c:148:static int bot_send_status(struct usbg_cmd *cmd, bool moved_data)\ndrivers/usb/gadget/function/f_tcm.c-149-{\n--\ndrivers/usb/gadget/function/f_tcm.c-183- */\ndrivers/usb/gadget/function/f_tcm.c:184:static int bot_send_status_response(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-185-{\n--\ndrivers/usb/gadget/function/f_tcm.c-193-/* Read request completed, now we have to send the CSW */\ndrivers/usb/gadget/function/f_tcm.c:194:static void bot_read_compl(struct usb_ep *ep, struct usb_request *req)\ndrivers/usb/gadget/function/f_tcm.c-195-{\n--\ndrivers/usb/gadget/function/f_tcm.c-208-\ndrivers/usb/gadget/function/f_tcm.c:209:static int bot_send_read_response(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-210-{\n--\ndrivers/usb/gadget/function/f_tcm.c-247-\ndrivers/usb/gadget/function/f_tcm.c:248:static void usbg_data_write_cmpl(struct usb_ep *, struct usb_request *);\ndrivers/usb/gadget/function/f_tcm.c:249:static int usbg_prepare_w_request(struct usbg_cmd *, struct usb_request *);\ndrivers/usb/gadget/function/f_tcm.c-250-\ndrivers/usb/gadget/function/f_tcm.c:251:static int bot_send_write_request(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-252-{\n--\ndrivers/usb/gadget/function/f_tcm.c-273-\ndrivers/usb/gadget/function/f_tcm.c:274:static int bot_submit_command(struct f_uas *, void *, unsigned int);\ndrivers/usb/gadget/function/f_tcm.c-275-\ndrivers/usb/gadget/function/f_tcm.c:276:static void bot_cmd_complete(struct usb_ep *ep, struct usb_request *req)\ndrivers/usb/gadget/function/f_tcm.c-277-{\n--\ndrivers/usb/gadget/function/f_tcm.c-307-\ndrivers/usb/gadget/function/f_tcm.c:308:static int bot_prepare_reqs(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-309-{\n--\ndrivers/usb/gadget/function/f_tcm.c-364-\ndrivers/usb/gadget/function/f_tcm.c:365:static void bot_cleanup_old_alt(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-366-{\n--\ndrivers/usb/gadget/function/f_tcm.c-389-\ndrivers/usb/gadget/function/f_tcm.c:390:static void bot_set_alt(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-391-{\n--\ndrivers/usb/gadget/function/f_tcm.c-421-\ndrivers/usb/gadget/function/f_tcm.c:422:static int usbg_bot_setup(struct usb_function *f,\ndrivers/usb/gadget/function/f_tcm.c-423-\t\tconst struct usb_ctrlrequest *ctrl)\n--\ndrivers/usb/gadget/function/f_tcm.c-471-\ndrivers/usb/gadget/function/f_tcm.c:472:static int tcm_to_uasp_response(enum tcm_tmrsp_table code)\ndrivers/usb/gadget/function/f_tcm.c-473-{\n--\ndrivers/usb/gadget/function/f_tcm.c-488-\ndrivers/usb/gadget/function/f_tcm.c:489:static unsigned char uasp_to_tcm_func(int code)\ndrivers/usb/gadget/function/f_tcm.c-490-{\n--\ndrivers/usb/gadget/function/f_tcm.c-510-\ndrivers/usb/gadget/function/f_tcm.c:511:static void uasp_cleanup_one_stream(struct f_uas *fu, struct uas_stream *stream)\ndrivers/usb/gadget/function/f_tcm.c-512-{\n--\ndrivers/usb/gadget/function/f_tcm.c-525-\ndrivers/usb/gadget/function/f_tcm.c:526:static void uasp_free_cmdreq(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-527-{\n--\ndrivers/usb/gadget/function/f_tcm.c-537-\ndrivers/usb/gadget/function/f_tcm.c:538:static void uasp_cleanup_old_alt(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-539-{\n--\ndrivers/usb/gadget/function/f_tcm.c-554-\ndrivers/usb/gadget/function/f_tcm.c:555:static void uasp_status_data_cmpl(struct usb_ep *ep, struct usb_request *req);\ndrivers/usb/gadget/function/f_tcm.c-556-\ndrivers/usb/gadget/function/f_tcm.c:557:static int uasp_prepare_r_request(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-558-{\n--\ndrivers/usb/gadget/function/f_tcm.c-590-\ndrivers/usb/gadget/function/f_tcm.c:591:static void uasp_prepare_status(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-592-{\n--\ndrivers/usb/gadget/function/f_tcm.c-613-\ndrivers/usb/gadget/function/f_tcm.c:614:static void uasp_prepare_response(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-615-{\n--\ndrivers/usb/gadget/function/f_tcm.c-665-\ndrivers/usb/gadget/function/f_tcm.c:666:static void usbg_release_cmd(struct se_cmd *se_cmd);\ndrivers/usb/gadget/function/f_tcm.c:667:static int uasp_send_tm_response(struct usbg_cmd *cmd);\ndrivers/usb/gadget/function/f_tcm.c-668-\ndrivers/usb/gadget/function/f_tcm.c:669:static void uasp_status_data_cmpl(struct usb_ep *ep, struct usb_request *req)\ndrivers/usb/gadget/function/f_tcm.c-670-{\n--\ndrivers/usb/gadget/function/f_tcm.c-749-\ndrivers/usb/gadget/function/f_tcm.c:750:static int uasp_send_status_response(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-751-{\n--\ndrivers/usb/gadget/function/f_tcm.c-761-\ndrivers/usb/gadget/function/f_tcm.c:762:static int uasp_send_tm_response(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-763-{\n--\ndrivers/usb/gadget/function/f_tcm.c-773-\ndrivers/usb/gadget/function/f_tcm.c:774:static int uasp_send_read_response(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-775-{\n--\ndrivers/usb/gadget/function/f_tcm.c-816-\ndrivers/usb/gadget/function/f_tcm.c:817:static int uasp_send_write_request(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-818-{\n--\ndrivers/usb/gadget/function/f_tcm.c-859-\ndrivers/usb/gadget/function/f_tcm.c:860:static int usbg_submit_command(struct f_uas *, struct usb_request *);\ndrivers/usb/gadget/function/f_tcm.c-861-\ndrivers/usb/gadget/function/f_tcm.c:862:static void uasp_cmd_complete(struct usb_ep *ep, struct usb_request *req)\ndrivers/usb/gadget/function/f_tcm.c-863-{\n--\ndrivers/usb/gadget/function/f_tcm.c-876-\ndrivers/usb/gadget/function/f_tcm.c:877:static int uasp_alloc_stream_res(struct f_uas *fu, struct uas_stream *stream)\ndrivers/usb/gadget/function/f_tcm.c-878-{\n--\ndrivers/usb/gadget/function/f_tcm.c-904-\ndrivers/usb/gadget/function/f_tcm.c:905:static int uasp_alloc_cmd(struct f_uas *fu, int i)\ndrivers/usb/gadget/function/f_tcm.c-906-{\n--\ndrivers/usb/gadget/function/f_tcm.c-926-\ndrivers/usb/gadget/function/f_tcm.c:927:static int uasp_prepare_reqs(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-928-{\n--\ndrivers/usb/gadget/function/f_tcm.c-963-\ndrivers/usb/gadget/function/f_tcm.c:964:static void uasp_set_alt(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-965-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1012-\ndrivers/usb/gadget/function/f_tcm.c:1013:static int get_cmd_dir(const unsigned char *cdb)\ndrivers/usb/gadget/function/f_tcm.c-1014-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1076-\ndrivers/usb/gadget/function/f_tcm.c:1077:static void usbg_data_write_cmpl(struct usb_ep *ep, struct usb_request *req)\ndrivers/usb/gadget/function/f_tcm.c-1078-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1122-\ndrivers/usb/gadget/function/f_tcm.c:1123:static int usbg_prepare_w_request(struct usbg_cmd *cmd, struct usb_request *req)\ndrivers/usb/gadget/function/f_tcm.c-1124-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1150-\ndrivers/usb/gadget/function/f_tcm.c:1151:static int usbg_send_status_response(struct se_cmd *se_cmd)\ndrivers/usb/gadget/function/f_tcm.c-1152-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1162-\ndrivers/usb/gadget/function/f_tcm.c:1163:static int usbg_send_write_request(struct se_cmd *se_cmd)\ndrivers/usb/gadget/function/f_tcm.c-1164-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1174-\ndrivers/usb/gadget/function/f_tcm.c:1175:static int usbg_send_read_response(struct se_cmd *se_cmd)\ndrivers/usb/gadget/function/f_tcm.c-1176-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1186-\ndrivers/usb/gadget/function/f_tcm.c:1187:static void usbg_aborted_task(struct se_cmd *se_cmd);\ndrivers/usb/gadget/function/f_tcm.c-1188-\ndrivers/usb/gadget/function/f_tcm.c:1189:static void usbg_submit_tmr(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-1190-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1203-\ndrivers/usb/gadget/function/f_tcm.c:1204:static void usbg_submit_cmd(struct usbg_cmd *cmd)\ndrivers/usb/gadget/function/f_tcm.c-1205-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1251-\ndrivers/usb/gadget/function/f_tcm.c:1252:static void usbg_cmd_work(struct work_struct *work)\ndrivers/usb/gadget/function/f_tcm.c-1253-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1342-\ndrivers/usb/gadget/function/f_tcm.c:1343:static struct usbg_cmd *usbg_get_cmd(struct f_uas *fu,\ndrivers/usb/gadget/function/f_tcm.c-1344-\t\tstruct tcm_usbg_nexus *tv_nexus, u32 scsi_tag)\n--\ndrivers/usb/gadget/function/f_tcm.c-1364-\ndrivers/usb/gadget/function/f_tcm.c:1365:static void usbg_release_cmd(struct se_cmd *);\ndrivers/usb/gadget/function/f_tcm.c-1366-\ndrivers/usb/gadget/function/f_tcm.c:1367:static int usbg_submit_command(struct f_uas *fu, struct usb_request *req)\ndrivers/usb/gadget/function/f_tcm.c-1368-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1469-\ndrivers/usb/gadget/function/f_tcm.c:1470:static void bot_cmd_work(struct work_struct *work)\ndrivers/usb/gadget/function/f_tcm.c-1471-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1518-\ndrivers/usb/gadget/function/f_tcm.c:1519:static int bot_submit_command(struct f_uas *fu,\ndrivers/usb/gadget/function/f_tcm.c-1520-\t\tvoid *cmdbuf, unsigned int len)\n--\ndrivers/usb/gadget/function/f_tcm.c-1569-\ndrivers/usb/gadget/function/f_tcm.c:1570:static int usbg_check_true(struct se_portal_group *se_tpg)\ndrivers/usb/gadget/function/f_tcm.c-1571-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1574-\ndrivers/usb/gadget/function/f_tcm.c:1575:static char *usbg_get_fabric_wwn(struct se_portal_group *se_tpg)\ndrivers/usb/gadget/function/f_tcm.c-1576-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1583-\ndrivers/usb/gadget/function/f_tcm.c:1584:static u16 usbg_get_tag(struct se_portal_group *se_tpg)\ndrivers/usb/gadget/function/f_tcm.c-1585-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1590-\ndrivers/usb/gadget/function/f_tcm.c:1591:static void usbg_release_cmd(struct se_cmd *se_cmd)\ndrivers/usb/gadget/function/f_tcm.c-1592-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1601-\ndrivers/usb/gadget/function/f_tcm.c:1602:static void usbg_queue_tm_rsp(struct se_cmd *se_cmd)\ndrivers/usb/gadget/function/f_tcm.c-1603-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1608-\ndrivers/usb/gadget/function/f_tcm.c:1609:static void usbg_aborted_task(struct se_cmd *se_cmd)\ndrivers/usb/gadget/function/f_tcm.c-1610-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1630-\ndrivers/usb/gadget/function/f_tcm.c:1631:static const char *usbg_check_wwn(const char *name)\ndrivers/usb/gadget/function/f_tcm.c-1632-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1645-\ndrivers/usb/gadget/function/f_tcm.c:1646:static int usbg_init_nodeacl(struct se_node_acl *se_nacl, const char *name)\ndrivers/usb/gadget/function/f_tcm.c-1647-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1652-\ndrivers/usb/gadget/function/f_tcm.c:1653:static struct se_portal_group *usbg_make_tpg(struct se_wwn *wwn,\ndrivers/usb/gadget/function/f_tcm.c-1654-\t\t\t\t\t     const char *name)\n--\ndrivers/usb/gadget/function/f_tcm.c-1751-\ndrivers/usb/gadget/function/f_tcm.c:1752:static int tcm_usbg_drop_nexus(struct usbg_tpg *);\ndrivers/usb/gadget/function/f_tcm.c-1753-\ndrivers/usb/gadget/function/f_tcm.c:1754:static void usbg_drop_tpg(struct se_portal_group *se_tpg)\ndrivers/usb/gadget/function/f_tcm.c-1755-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1798-\ndrivers/usb/gadget/function/f_tcm.c:1799:static struct se_wwn *usbg_make_tport(\ndrivers/usb/gadget/function/f_tcm.c-1800-\tstruct target_fabric_configfs *tf,\n--\ndrivers/usb/gadget/function/f_tcm.c-1820-\ndrivers/usb/gadget/function/f_tcm.c:1821:static void usbg_drop_tport(struct se_wwn *wwn)\ndrivers/usb/gadget/function/f_tcm.c-1822-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1830- */\ndrivers/usb/gadget/function/f_tcm.c:1831:static ssize_t usbg_wwn_version_show(struct config_item *item,  char *page)\ndrivers/usb/gadget/function/f_tcm.c-1832-{\n--\ndrivers/usb/gadget/function/f_tcm.c=1838=static struct configfs_attribute *usbg_wwn_attrs[] = {\n--\ndrivers/usb/gadget/function/f_tcm.c-1842-\ndrivers/usb/gadget/function/f_tcm.c:1843:static int usbg_attach(struct usbg_tpg *);\ndrivers/usb/gadget/function/f_tcm.c:1844:static void usbg_detach(struct usbg_tpg *);\ndrivers/usb/gadget/function/f_tcm.c-1845-\ndrivers/usb/gadget/function/f_tcm.c:1846:static int usbg_enable_tpg(struct se_portal_group *se_tpg, bool enable)\ndrivers/usb/gadget/function/f_tcm.c-1847-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1862-\ndrivers/usb/gadget/function/f_tcm.c:1863:static ssize_t tcm_usbg_tpg_nexus_show(struct config_item *item, char *page)\ndrivers/usb/gadget/function/f_tcm.c-1864-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1882-\ndrivers/usb/gadget/function/f_tcm.c:1883:static int usbg_alloc_sess_cb(struct se_portal_group *se_tpg,\ndrivers/usb/gadget/function/f_tcm.c-1884-\t\t\t      struct se_session *se_sess, void *p)\n--\ndrivers/usb/gadget/function/f_tcm.c-1892-\ndrivers/usb/gadget/function/f_tcm.c:1893:static int tcm_usbg_make_nexus(struct usbg_tpg *tpg, char *name)\ndrivers/usb/gadget/function/f_tcm.c-1894-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1928-\ndrivers/usb/gadget/function/f_tcm.c:1929:static int tcm_usbg_drop_nexus(struct usbg_tpg *tpg)\ndrivers/usb/gadget/function/f_tcm.c-1930-{\n--\ndrivers/usb/gadget/function/f_tcm.c-1966-\ndrivers/usb/gadget/function/f_tcm.c:1967:static ssize_t tcm_usbg_tpg_nexus_store(struct config_item *item,\ndrivers/usb/gadget/function/f_tcm.c-1968-\t\tconst char *page, size_t count)\n--\ndrivers/usb/gadget/function/f_tcm.c=2005=static struct configfs_attribute *usbg_base_attrs[] = {\n--\ndrivers/usb/gadget/function/f_tcm.c-2009-\ndrivers/usb/gadget/function/f_tcm.c:2010:static int usbg_port_link(struct se_portal_group *se_tpg, struct se_lun *lun)\ndrivers/usb/gadget/function/f_tcm.c-2011-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2018-\ndrivers/usb/gadget/function/f_tcm.c:2019:static void usbg_port_unlink(struct se_portal_group *se_tpg,\ndrivers/usb/gadget/function/f_tcm.c-2020-\t\tstruct se_lun *se_lun)\n--\ndrivers/usb/gadget/function/f_tcm.c-2027-\ndrivers/usb/gadget/function/f_tcm.c:2028:static int usbg_check_stop_free(struct se_cmd *se_cmd)\ndrivers/usb/gadget/function/f_tcm.c-2029-{\n--\ndrivers/usb/gadget/function/f_tcm.c=2309=static struct usb_gadget_strings *tcm_strings[] = {\n--\ndrivers/usb/gadget/function/f_tcm.c-2313-\ndrivers/usb/gadget/function/f_tcm.c:2314:static int tcm_bind(struct usb_configuration *c, struct usb_function *f)\ndrivers/usb/gadget/function/f_tcm.c-2315-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2392-\ndrivers/usb/gadget/function/f_tcm.c:2393:static void tcm_cleanup_old_alt(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-2394-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2401-\ndrivers/usb/gadget/function/f_tcm.c:2402:static void tcm_delayed_set_alt_done(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-2403-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2411-\ndrivers/usb/gadget/function/f_tcm.c:2412:static bool tcm_delayed_set_alt_cancelled(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-2413-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2423-\ndrivers/usb/gadget/function/f_tcm.c:2424:static bool tcm_complete_delayed_status(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-2425-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2464-\ndrivers/usb/gadget/function/f_tcm.c:2465:static bool tcm_cancel_delayed_set_alt(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-2466-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2496-\ndrivers/usb/gadget/function/f_tcm.c:2497:static void tcm_cancel_delayed_set_alt_sync(struct f_uas *fu)\ndrivers/usb/gadget/function/f_tcm.c-2498-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2513-\ndrivers/usb/gadget/function/f_tcm.c:2514:static void tcm_delayed_set_alt(struct work_struct *wq)\ndrivers/usb/gadget/function/f_tcm.c-2515-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2546-\ndrivers/usb/gadget/function/f_tcm.c:2547:static int tcm_get_alt(struct usb_function *f, unsigned intf)\ndrivers/usb/gadget/function/f_tcm.c-2548-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2561-\ndrivers/usb/gadget/function/f_tcm.c:2562:static int tcm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)\ndrivers/usb/gadget/function/f_tcm.c-2563-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2588-\ndrivers/usb/gadget/function/f_tcm.c:2589:static void tcm_disable(struct usb_function *f)\ndrivers/usb/gadget/function/f_tcm.c-2590-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2596-\ndrivers/usb/gadget/function/f_tcm.c:2597:static int tcm_setup(struct usb_function *f,\ndrivers/usb/gadget/function/f_tcm.c-2598-\t\tconst struct usb_ctrlrequest *ctrl)\n--\ndrivers/usb/gadget/function/f_tcm.c-2607-\ndrivers/usb/gadget/function/f_tcm.c:2608:static inline struct f_tcm_opts *to_f_tcm_opts(struct config_item *item)\ndrivers/usb/gadget/function/f_tcm.c-2609-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2613-\ndrivers/usb/gadget/function/f_tcm.c:2614:static void tcm_attr_release(struct config_item *item)\ndrivers/usb/gadget/function/f_tcm.c-2615-{\n--\ndrivers/usb/gadget/function/f_tcm.c=2625=static const struct config_item_type tcm_func_type = {\n--\ndrivers/usb/gadget/function/f_tcm.c-2629-\ndrivers/usb/gadget/function/f_tcm.c:2630:static void tcm_free_inst(struct usb_function_instance *f)\ndrivers/usb/gadget/function/f_tcm.c-2631-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2647-\ndrivers/usb/gadget/function/f_tcm.c:2648:static int tcm_register_callback(struct usb_function_instance *f)\ndrivers/usb/gadget/function/f_tcm.c-2649-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2658-\ndrivers/usb/gadget/function/f_tcm.c:2659:static void tcm_unregister_callback(struct usb_function_instance *f)\ndrivers/usb/gadget/function/f_tcm.c-2660-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2669-\ndrivers/usb/gadget/function/f_tcm.c:2670:static int usbg_attach(struct usbg_tpg *tpg)\ndrivers/usb/gadget/function/f_tcm.c-2671-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2680-\ndrivers/usb/gadget/function/f_tcm.c:2681:static void usbg_detach(struct usbg_tpg *tpg)\ndrivers/usb/gadget/function/f_tcm.c-2682-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2689-\ndrivers/usb/gadget/function/f_tcm.c:2690:static int tcm_set_name(struct usb_function_instance *f, const char *name)\ndrivers/usb/gadget/function/f_tcm.c-2691-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2702-\ndrivers/usb/gadget/function/f_tcm.c:2703:static struct usb_function_instance *tcm_alloc_inst(void)\ndrivers/usb/gadget/function/f_tcm.c-2704-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2737-\ndrivers/usb/gadget/function/f_tcm.c:2738:static void tcm_free(struct usb_function *f)\ndrivers/usb/gadget/function/f_tcm.c-2739-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2745-\ndrivers/usb/gadget/function/f_tcm.c:2746:static void tcm_unbind(struct usb_configuration *c, struct usb_function *f)\ndrivers/usb/gadget/function/f_tcm.c-2747-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2754-\ndrivers/usb/gadget/function/f_tcm.c:2755:static struct usb_function *tcm_alloc(struct usb_function_instance *fi)\ndrivers/usb/gadget/function/f_tcm.c-2756-{\n--\ndrivers/usb/gadget/function/f_tcm.c=2793=DECLARE_USB_FUNCTION(tcm, tcm_alloc_inst, tcm_alloc);\ndrivers/usb/gadget/function/f_tcm.c-2794-\ndrivers/usb/gadget/function/f_tcm.c:2795:static int __init tcm_init(void)\ndrivers/usb/gadget/function/f_tcm.c-2796-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2808-}\ndrivers/usb/gadget/function/f_tcm.c:2809:module_init(tcm_init);\ndrivers/usb/gadget/function/f_tcm.c-2810-\ndrivers/usb/gadget/function/f_tcm.c:2811:static void __exit tcm_exit(void)\ndrivers/usb/gadget/function/f_tcm.c-2812-{\n--\ndrivers/usb/gadget/function/f_tcm.c-2815-}\ndrivers/usb/gadget/function/f_tcm.c:2816:module_exit(tcm_exit);\ndrivers/usb/gadget/function/f_tcm.c-2817-\n"
}

gemini-3.1-pro-preview

null

null

							input: 23058
							output: 32
							thoughts: 220
						

**My Assessment of the USB Gadget Configuration**

Okay, so I see that `usbg_make_tpg` and `usbg_drop_tpg` are being utilized in the `target_core_fabric_ops` structure as `fabric_make_tpg` and `fabric_drop_tpg`. This implies they are being called by the target core ConfigFS code, which is good. For my analysis, I'll refer to them simply as `usbg_make_tpg` and `usbg_drop_tpg` for ease of reference – FocusSymbols, if you will.

Now, let's break down the necessary configuration symbols. We have `USB_CONFIGFS`, `TARGET_CORE`, and `USB_CONFIGFS_F_TCM`. `USB_CONFIGFS_F_TCM` seems to select `USB_F_TCM`, which is what we expect. `TARGET_CORE` in turn is selecting `CONFIGFS_FS`. This looks, at first glance, like a comprehensive set of options.

But wait a minute, I need to double-check something. `USB_CONFIGFS` depends on `USB_GADGET`. I need to ensure that this isn't going to cause any unforeseen issues. Let's make sure that that is properly configured as well.

{
  "Expression": "config USB_GADGET",
  "PathPrefix": "drivers/usb/gadget/"
}

{
  "Output": "drivers/usb/gadget/Kconfig-16-\ndrivers/usb/gadget/Kconfig:17:menuconfig USB_GADGET\ndrivers/usb/gadget/Kconfig-18-\ttristate \"USB Gadget Support\"\n--\ndrivers/usb/gadget/Kconfig=47=if USB_GADGET\ndrivers/usb/gadget/Kconfig-48-\ndrivers/usb/gadget/Kconfig:49:config USB_GADGET_DEBUG\ndrivers/usb/gadget/Kconfig-50-\tbool \"Debugging messages (DEVELOPMENT)\"\n--\ndrivers/usb/gadget/Kconfig-62-\ndrivers/usb/gadget/Kconfig:63:config USB_GADGET_VERBOSE\ndrivers/usb/gadget/Kconfig-64-\tbool \"Verbose debugging Messages (DEVELOPMENT)\"\n--\ndrivers/usb/gadget/Kconfig-76-\ndrivers/usb/gadget/Kconfig:77:config USB_GADGET_DEBUG_FILES\ndrivers/usb/gadget/Kconfig-78-\tbool \"Debugging information files (DEVELOPMENT)\"\n--\ndrivers/usb/gadget/Kconfig-87-\ndrivers/usb/gadget/Kconfig:88:config USB_GADGET_DEBUG_FS\ndrivers/usb/gadget/Kconfig-89-\tbool \"Debugging information files in debugfs (DEVELOPMENT)\"\n--\ndrivers/usb/gadget/Kconfig-98-\ndrivers/usb/gadget/Kconfig:99:config USB_GADGET_VBUS_DRAW\ndrivers/usb/gadget/Kconfig-100-\tint \"Maximum VBUS Power usage (2-500 mA)\"\n--\ndrivers/usb/gadget/Kconfig-115-\ndrivers/usb/gadget/Kconfig:116:config USB_GADGET_STORAGE_NUM_BUFFERS\ndrivers/usb/gadget/Kconfig-117-\tint \"Number of storage pipeline buffers\"\n--\ndrivers/usb/gadget/legacy/Kconfig=190=config USB_G_NCM\n--\ndrivers/usb/gadget/legacy/Kconfig-205-\ndrivers/usb/gadget/legacy/Kconfig:206:config USB_GADGETFS\ndrivers/usb/gadget/legacy/Kconfig-207-\ttristate \"Gadget Filesystem\"\n--\ndrivers/usb/gadget/legacy/Kconfig=262=config USB_MASS_STORAGE\n--\ndrivers/usb/gadget/legacy/Kconfig-278-\ndrivers/usb/gadget/legacy/Kconfig:279:config USB_GADGET_TARGET\ndrivers/usb/gadget/legacy/Kconfig-280-\ttristate \"USB Gadget Target Fabric Module\"\n--\ndrivers/usb/gadget/udc/Kconfig=347=config USB_EG20T\n--\ndrivers/usb/gadget/udc/Kconfig-370-\ndrivers/usb/gadget/udc/Kconfig:371:config USB_GADGET_XILINX\ndrivers/usb/gadget/udc/Kconfig-372-\ttristate \"Xilinx USB Driver\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 24367
							output: 36
							thoughts: 23
						

Okay, here's my take on those thoughts, tailored for an expert audience, and delivered as a first-person summary:

**USB Gadget Configuration - A Quick Check**

Right, so we're looking at integrating a USB Gadget. The initial thought is, naturally, that we'll need `USB_GADGET` enabled. Before I dive too deep into the specific device configuration or function setup, let's take a beat and quickly verify the dependencies. We can't afford to waste time chasing down build errors later due to a missing component. A quick check of the Kconfig for `USB_GADGET` will reveal all the related settings that need consideration. We want to ensure everything is set up to allow the next stage of config to happen as seamlessly as possible.

{
  "File": "drivers/usb/gadget/Kconfig",
  "FirstLine": 10,
  "LineCount": 20
}

{
  "Contents": "  10:\t#  - Peripherals (like PDAs) need CONFIG_USB_GADGET (with \"B\" jacks).\n  11:\t#  - Some systems have both kinds of controllers.\n  12:\t#\n  13:\t# With help from a special transceiver and a \"Mini-AB\" jack, systems with\n  14:\t# both kinds of controller can also support \"USB On-the-Go\" (CONFIG_USB_OTG).\n  15:\t#\n  16:\t\n  17:\tmenuconfig USB_GADGET\n  18:\t\ttristate \"USB Gadget Support\"\n  19:\t\tselect USB_COMMON\n  20:\t\tselect NLS\n  21:\t\thelp\n  22:\t\t   USB is a host/device protocol, organized with one host (such as a\n  23:\t\t   PC) controlling up to 127 peripheral devices.\n  24:\t\t   The USB hardware is asymmetric, which makes it easier to set up:\n  25:\t\t   you can't connect a \"to-the-host\" connector to a peripheral.\n  26:\t\n  27:\t\t   Linux can run in the host, or in the peripheral.  In both cases\n  28:\t\t   you need a low level bus controller driver, and some software\n  29:\t\t   talking to it.  Peripheral controllers are often discrete silicon,\n"
}

gemini-3.1-pro-preview

null

null

							input: 24932
							output: 36
							thoughts: 123
						

**My Gadget Configuration Considerations**

Okay, so I'm digging into these USB gadget configurations. The first thing I'm noting is that `USB_GADGET` itself is dependency-free. That simplifies things, but doesn't tell the whole story. The relevant configs then are `USB_GADGET`, `USB_CONFIGFS`, `TARGET_CORE`, and `USB_CONFIGFS_F_TCM`. Now, to actually *test* these gadgets effectively, I need to consider host controllers. The question now becomes, do I need `USB_DUMMY_HCD` for testing? Given syzkaller's typical approach, it usually utilizes `USB_DUMMY_HCD` or potentially `USB_RAW_GADGET` for this purpose. I should check where `USB_DUMMY_HCD` is defined, and it looks like it is located in `drivers/usb/gadget/udc/Kconfig`. I need to review it.

{
  "Expression": "config USB_DUMMY_HCD",
  "PathPrefix": "drivers/usb/gadget/"
}

{
  "Output": "drivers/usb/gadget/udc/Kconfig=422=source \"drivers/usb/gadget/udc/cdns2/Kconfig\"\n--\ndrivers/usb/gadget/udc/Kconfig-427-\ndrivers/usb/gadget/udc/Kconfig:428:config USB_DUMMY_HCD\ndrivers/usb/gadget/udc/Kconfig-429-\ttristate \"Dummy HCD (DEVELOPMENT)\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 25427
							output: 40
							thoughts: 25
						

Here's my summary, as though I'm thinking through this process:

**Diving into the UDC Kconfig**

Okay, I need to understand how USB Device Controller (UDC) support is configured within the kernel. Let's see... the `drivers/usb/gadget/udc/Kconfig` file is the logical place to start. Now, where was I last looking? Ah, yes, line 428 is a good starting point. I want to see how the various UDC drivers are brought into the configuration process, what the dependencies look like, and the default settings. It's time to dig in and remind myself of the details of the UDC subsystem Kconfig. Hopefully, this provides the context I need.

{
  "File": "drivers/usb/gadget/udc/Kconfig",
  "FirstLine": 425,
  "LineCount": 20
}

{
  "Contents": " 425:\t# LAST -- dummy/emulated controller\n 426:\t#\n 427:\t\n 428:\tconfig USB_DUMMY_HCD\n 429:\t\ttristate \"Dummy HCD (DEVELOPMENT)\"\n 430:\t\tdepends on USB=y || (USB=m \u0026\u0026 USB_GADGET=m)\n 431:\t\thelp\n 432:\t\t  This host controller driver emulates USB, looping all data transfer\n 433:\t\t  requests back to a USB \"gadget driver\" in the same host.  The host\n 434:\t\t  side is the controller; the gadget side is the device.  Gadget drivers\n 435:\t\t  can be high, full, or low speed; and they have access to endpoints\n 436:\t\t  like those from NET2280, PXA2xx, or SA1100 hardware.\n 437:\t\n 438:\t\t  This may help in some stages of creating a driver to embed in a\n 439:\t\t  Linux device, since it lets you debug several parts of the gadget\n 440:\t\t  driver without its hardware or drivers being involved.\n 441:\t\n 442:\t\t  Since such a gadget side driver needs to interoperate with a host\n 443:\t\t  side Linux-USB device driver, this may help to debug both sides\n 444:\t\t  of a USB protocol stack.\n"
}

gemini-3.1-pro-preview

null

null

							input: 26016
							output: 34
							thoughts: 66
						

**Considering USB Gadget Testing Configurations**

Okay, so I'm thinking about how to configure this test environment for USB gadgets, and Syzkaller seems like the go-to resource for a solid foundation. I recall seeing them leverage `USB_DUMMY_HCD` quite often in their tests. That immediately makes it a strong contender for inclusion in my configuration, given its proven track record in that context. But hold on, I seem to remember seeing `USB_RAW_GADGET` used alongside it. It's time to double-check that `USB_RAW_GADGET` configuration, because if it's also a staple in Syzkaller’s testing methodology, I definitely need to understand its role and how it complements `USB_DUMMY_HCD`. A thorough review of its functionalities is now warranted.

{
  "Expression": "config USB_RAW_GADGET",
  "PathPrefix": "drivers/usb/gadget/"
}

{
  "Output": "drivers/usb/gadget/legacy/Kconfig=501=config USB_G_WEBCAM\n--\ndrivers/usb/gadget/legacy/Kconfig-515-\ndrivers/usb/gadget/legacy/Kconfig:516:config USB_RAW_GADGET\ndrivers/usb/gadget/legacy/Kconfig-517-\ttristate \"USB Raw Gadget\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 26398
							output: 39
							thoughts: 24
						

Here's my summary, as though I'm thinking through this process:

**Diving into the USB Gadget Configuration**

Okay, I need to get a handle on how this USB gadget functionality is configured. Time to go deep and understand the dependencies and options. Let's see... the `drivers/usb/gadget/legacy/Kconfig` file should give me the core build configuration options, and I remember there's some interesting stuff around the legacy gadget implementation I need to check. Right, let's zero in on roughly line 516. That should be a good starting point to identify the critical configuration parameters. Hopefully, this section will shed some light on the specific settings I'm interested in. I'm aiming to understand the relation between the options presented and the corresponding driver functions.

{
  "File": "drivers/usb/gadget/legacy/Kconfig",
  "FirstLine": 510,
  "LineCount": 20
}

{
  "Contents": " 510:\t\t  device. It provides a userspace API to process UVC control requests\n 511:\t\t  and stream video data to the host.\n 512:\t\n 513:\t\t  Say \"y\" to link the driver statically, or \"m\" to build a\n 514:\t\t  dynamically linked module called \"g_webcam\".\n 515:\t\n 516:\tconfig USB_RAW_GADGET\n 517:\t\ttristate \"USB Raw Gadget\"\n 518:\t\thelp\n 519:\t\t  USB Raw Gadget is a gadget driver that gives userspace low-level\n 520:\t\t  control over the gadget's communication process.\n 521:\t\n 522:\t\t  Like any other gadget driver, Raw Gadget implements USB devices via\n 523:\t\t  the USB gadget API. Unlike most gadget drivers, Raw Gadget does not\n 524:\t\t  implement any concrete USB functions itself but requires userspace\n 525:\t\t  to do that.\n 526:\t\n 527:\t\t  See Documentation/usb/raw-gadget.rst for details.\n 528:\t\n 529:\t\t  Say \"y\" to link the driver statically, or \"m\" to build a\n"
}

gemini-3.1-pro-preview

null

null

							input: 26960
							output: 145
							thoughts: 1286
						

**Analysis of the TCM Configfs Patch**

Okay, so this patch is focused on `f_tcm.c`, which is a ConfigFS function. My main concern here revolves around `USB_CONFIGFS` and `USB_CONFIGFS_F_TCM`, naturally. It's a good idea to include `USB_DUMMY_HCD` as well, just in case. Let's start by listing the key configs:

*   `USB_GADGET`
*   `USB_CONFIGFS`
*   `TARGET_CORE`
*   `USB_CONFIGFS_F_TCM`
*   `USB_DUMMY_HCD`

Now, let me check the dependencies for `USB_CONFIGFS_F_TCM`. It relies on `TARGET_CORE` and `USB_CONFIGFS`. `TARGET_CORE` depends on `BLOCK`, and `USB_CONFIGFS` needs `USB_GADGET`. `USB_DUMMY_HCD` has dependencies on both `USB` and `USB_GADGET`. So the full set of dependencies I need to consider are: `USB`, `BLOCK`, `USB_GADGET`, `USB_CONFIGFS`, `TARGET_CORE`, `USB_CONFIGFS_F_TCM`, and `USB_DUMMY_HCD`.

The patch modifies `usbg_make_tpg` and `usbg_drop_tpg`, and only those functions. That simplifies things. Let's confirm if these functions are static. Yes, they are. And are they inlined? No, they are assigned to function pointers within `usbg_ops`. This means that they have distinct addresses and will not be inlined by the compiler. That makes them perfect candidates for focus symbols.

I've taken a look at the code logic; the patch addresses a race condition within `usbg_make_tpg` and `usbg_drop_tpg`. This race involves the check of `opts->has_dep` and the use of `opts->dependent`. The patch fixes the issue by introducing a local variable to read `has_dep = opts->has_dep;` and uses that copy instead of the volatile variable. Additionally, it reorders the `config_item_get` and `mutex_unlock` operations. This is a clear functional change that fixes a genuine bug. Definitely worth fuzzing to ensure the fix is solid.

To summarize, my suggested configurations are:

*   `USB_GADGET`
*   `USB_CONFIGFS`
*   `TARGET_CORE`
*   `USB_CONFIGFS_F_TCM`
*   `USB_DUMMY_HCD`

And the `FocusSymbols` will be:

*   `usbg_make_tpg`
*   `usbg_drop_tpg`

My Reasoning: "The patch fixes a race condition in configfs dependency handling for the USB gadget TCM function. It modifies usbg_make_tpg and usbg_drop_tpg which are reachable via configfs. Fuzzing these functions will help verify the fix."

Time to call `set-results`.

{
  "EnableConfigs": [
    "USB_GADGET",
    "USB_CONFIGFS",
    "TARGET_CORE",
    "USB_CONFIGFS_F_TCM",
    "USB_DUMMY_HCD"
  ],
  "FocusSymbols": [
    "usbg_make_tpg",
    "usbg_drop_tpg"
  ],
  "Reasoning": "The patch fixes a race condition in configfs dependency handling for the USB gadget TCM function. It modifies usbg_make_tpg and usbg_drop_tpg which are reachable via configfs. Fuzzing these functions will help verify the fix.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "USB_GADGET",
    "USB_CONFIGFS",
    "TARGET_CORE",
    "USB_CONFIGFS_F_TCM",
    "USB_DUMMY_HCD"
  ],
  "FocusSymbols": [
    "usbg_make_tpg",
    "usbg_drop_tpg"
  ],
  "Reasoning": "The patch fixes a race condition in configfs dependency handling for the USB gadget TCM function. It modifies usbg_make_tpg and usbg_drop_tpg which are reachable via configfs. Fuzzing these functions will help verify the fix.",
  "WorthFuzzing": true
}