AI Trajectory


Trajectory: (Expand/Collapse All)
Seq Timestamp Type Name Duration
0/0 2026/06/30 23:31 flow patch-triage
0m Args: 
null

Results: 
{
  "EnableConfigs": [
    "NET_SCH_TEQL"
  ],
  "FocusSymbols": [
    "teql_master_xmit"
  ],
  "Reasoning": "The patch modifies the locking and RCU primitives in the teql_master_xmit function of the True Link Equalizer (TEQL) scheduler. This is a functional change that alters the execution flow and synchronization, so it should be fuzzed.",
  "WorthFuzzing": true
}
1/1 2026/06/30 23:31 action read-patch-diff
0m Args: 
null

Results: 
{
  "PatchDiff": "commit 82c7def28e2792e7eae4ab6765a960baf5cb8bc9\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Tue Jun 30 23:31:40 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c\nindex 24ba31f8c82855..5c42a29a981cb6 100644\n--- a/net/sched/sch_teql.c\n+++ b/net/sched/sch_teql.c\n@@ -311,14 +311,14 @@ static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)\n \tint subq = skb_get_queue_mapping(skb);\n \tstruct sk_buff *skb_res = NULL;\n \n-\trcu_read_lock_bh();\n-\n-\tstart = rcu_dereference_bh(master-\u003eslaves);\n-\n restart:\n \tnores = 0;\n \tbusy = 0;\n \n+\trcu_read_lock();\n+\n+\tstart = rcu_dereference(master-\u003eslaves);\n+\n \tq = start;\n \tif (!q)\n \t\tgoto drop;\n@@ -345,17 +345,17 @@ static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)\n \t\t\t\t    netdev_start_xmit(skb, slave, slave_txq, false) ==\n \t\t\t\t    NETDEV_TX_OK) {\n \t\t\t\t\t__netif_tx_unlock(slave_txq);\n-\t\t\t\t\tspin_lock_bh(\u0026master-\u003eslaves_lock);\n+\t\t\t\t\tspin_lock(\u0026master-\u003eslaves_lock);\n \t\t\t\t\tif (rcu_dereference_protected(master-\u003eslaves,\n \t\t\t\t\t\t\t\t      lockdep_is_held(\u0026master-\u003eslaves_lock)) == q)\n \t\t\t\t\t\trcu_assign_pointer(master-\u003eslaves,\n \t\t\t\t\t\t\t\t   rcu_dereference_protected(NEXT_SLAVE(q),\n \t\t\t\t\t\t\t\t\t\t\t     lockdep_is_held(\u0026master-\u003eslaves_lock)));\n-\t\t\t\t\tspin_unlock_bh(\u0026master-\u003eslaves_lock);\n+\t\t\t\t\tspin_unlock(\u0026master-\u003eslaves_lock);\n \t\t\t\t\tnetif_wake_queue(dev);\n \t\t\t\t\tmaster-\u003etx_packets++;\n \t\t\t\t\tmaster-\u003etx_bytes += length;\n-\t\t\t\t\trcu_read_unlock_bh();\n+\t\t\t\t\trcu_read_unlock();\n \t\t\t\t\treturn NETDEV_TX_OK;\n \t\t\t\t}\n \t\t\t\t__netif_tx_unlock(slave_txq);\n@@ -364,37 +364,38 @@ static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)\n \t\t\t\tbusy = 1;\n \t\t\tbreak;\n \t\tcase 1:\n-\t\t\tspin_lock_bh(\u0026master-\u003eslaves_lock);\n+\t\t\tspin_lock(\u0026master-\u003eslaves_lock);\n \t\t\tif (rcu_dereference_protected(master-\u003eslaves,\n \t\t\t\t\t\t      lockdep_is_held(\u0026master-\u003eslaves_lock)) == q)\n \t\t\t\trcu_assign_pointer(master-\u003eslaves,\n \t\t\t\t\t\t   rcu_dereference_protected(NEXT_SLAVE(q),\n \t\t\t\t\t\t\t\t\t     lockdep_is_held(\u0026master-\u003eslaves_lock)));\n-\t\t\tspin_unlock_bh(\u0026master-\u003eslaves_lock);\n-\t\t\trcu_read_unlock_bh();\n+\t\t\tspin_unlock(\u0026master-\u003eslaves_lock);\n+\t\t\trcu_read_unlock();\n \t\t\treturn NETDEV_TX_OK;\n \t\tdefault:\n \t\t\tnores = 1;\n \t\t\tbreak;\n \t\t}\n \t\t__skb_pull(skb, skb_network_offset(skb));\n-\t} while ((q = rcu_dereference_bh(NEXT_SLAVE(q))) != start);\n+\t} while ((q = rcu_dereference(NEXT_SLAVE(q))) != start);\n \n \tif (nores \u0026\u0026 skb_res == NULL) {\n \t\tskb_res = skb;\n+\t\trcu_read_unlock();\n \t\tgoto restart;\n \t}\n \n \tif (busy) {\n \t\tnetif_stop_queue(dev);\n-\t\trcu_read_unlock_bh();\n+\t\trcu_read_unlock();\n \t\treturn NETDEV_TX_BUSY;\n \t}\n \tmaster-\u003etx_errors++;\n \n drop:\n \tmaster-\u003etx_dropped++;\n-\trcu_read_unlock_bh();\n+\trcu_read_unlock();\n \tdev_kfree_skb(skb);\n \treturn NETDEV_TX_OK;\n }\n"
}
2/1 2026/06/30 23:31 agent patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
{
  "EnableConfigs": [
    "NET_SCH_TEQL"
  ],
  "FocusSymbols": [
    "teql_master_xmit"
  ],
  "Reasoning": "The patch modifies the locking and RCU primitives in the teql_master_xmit function of the True Link Equalizer (TEQL) scheduler. This is a functional change that alters the execution flow and synchronization, so it should be fuzzed.",
  "WorthFuzzing": true
}

Instruction: 
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).

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.
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.
   Do not list too generic configs (we already have them enabled). Only list those that
   specifically cover the modified code. 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.

Prompt: 
For your convenience, here is the diff of the changes:
commit 82c7def28e2792e7eae4ab6765a960baf5cb8bc9
Author: syz-cluster <triage@syzkaller.com>
Date:   Tue Jun 30 23:31:40 2026 +0000

    syz-cluster: applied patch under review

diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c
index 24ba31f8c82855..5c42a29a981cb6 100644
--- a/net/sched/sch_teql.c
+++ b/net/sched/sch_teql.c
@@ -311,14 +311,14 @@ static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
 	int subq = skb_get_queue_mapping(skb);
 	struct sk_buff *skb_res = NULL;
 
-	rcu_read_lock_bh();
-
-	start = rcu_dereference_bh(master->slaves);
-
 restart:
 	nores = 0;
 	busy = 0;
 
+	rcu_read_lock();
+
+	start = rcu_dereference(master->slaves);
+
 	q = start;
 	if (!q)
 		goto drop;
@@ -345,17 +345,17 @@ static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
 				    netdev_start_xmit(skb, slave, slave_txq, false) ==
 				    NETDEV_TX_OK) {
 					__netif_tx_unlock(slave_txq);
-					spin_lock_bh(&master->slaves_lock);
+					spin_lock(&master->slaves_lock);
 					if (rcu_dereference_protected(master->slaves,
 								      lockdep_is_held(&master->slaves_lock)) == q)
 						rcu_assign_pointer(master->slaves,
 								   rcu_dereference_protected(NEXT_SLAVE(q),
 											     lockdep_is_held(&master->slaves_lock)));
-					spin_unlock_bh(&master->slaves_lock);
+					spin_unlock(&master->slaves_lock);
 					netif_wake_queue(dev);
 					master->tx_packets++;
 					master->tx_bytes += length;
-					rcu_read_unlock_bh();
+					rcu_read_unlock();
 					return NETDEV_TX_OK;
 				}
 				__netif_tx_unlock(slave_txq);
@@ -364,37 +364,38 @@ static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
 				busy = 1;
 			break;
 		case 1:
-			spin_lock_bh(&master->slaves_lock);
+			spin_lock(&master->slaves_lock);
 			if (rcu_dereference_protected(master->slaves,
 						      lockdep_is_held(&master->slaves_lock)) == q)
 				rcu_assign_pointer(master->slaves,
 						   rcu_dereference_protected(NEXT_SLAVE(q),
 									     lockdep_is_held(&master->slaves_lock)));
-			spin_unlock_bh(&master->slaves_lock);
-			rcu_read_unlock_bh();
+			spin_unlock(&master->slaves_lock);
+			rcu_read_unlock();
 			return NETDEV_TX_OK;
 		default:
 			nores = 1;
 			break;
 		}
 		__skb_pull(skb, skb_network_offset(skb));
-	} while ((q = rcu_dereference_bh(NEXT_SLAVE(q))) != start);
+	} while ((q = rcu_dereference(NEXT_SLAVE(q))) != start);
 
 	if (nores && skb_res == NULL) {
 		skb_res = skb;
+		rcu_read_unlock();
 		goto restart;
 	}
 
 	if (busy) {
 		netif_stop_queue(dev);
-		rcu_read_unlock_bh();
+		rcu_read_unlock();
 		return NETDEV_TX_BUSY;
 	}
 	master->tx_errors++;
 
 drop:
 	master->tx_dropped++;
-	rcu_read_unlock_bh();
+	rcu_read_unlock();
 	dev_kfree_skb(skb);
 	return NETDEV_TX_OK;
 }

3/2 2026/06/30 23:31 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 2765
							output: 31
							thoughts: 131

Thoughts: 
**Analyzing the `sch_teql.c` Patch**

Okay, so I've got this patch here that's touching `net/sched/sch_teql.c`. Immediately, I see it's making some pretty significant concurrency changes. It's swapping out `_bh` variants of the locking primitives for their non-`_bh` counterparts. Specifically, it's replacing `rcu_read_lock_bh()` with `rcu_read_lock()`, `rcu_dereference_bh()` with `rcu_dereference()`, and the same with spinlocks. That's a red flag – definitely warrants a deeper look. And the fact that they've moved the `rcu_read_lock()` inside the `restart:` loop? That's... interesting. I'll need to understand the reasoning behind *that* shift. I know it isn't an issue, but is it correct?

My first instinct is to understand the context. What's the configuration that enables this scheduler? I need to check the code itself to determine which configuration options activate `sch_teql.c`. I need to figure out how this component interacts with the rest of the network stack. I know where the code is; time to start digging.

4/2 2026/06/30 23:31 tool grepper
0m Args: 
{
  "Expression": "sch_teql.o",
  "PathPrefix": "net/sched/Makefile"
}

Results: 
{
  "Output": "net/sched/Makefile=42=obj-$(CONFIG_NET_SCH_TBF)\t+= sch_tbf.o\nnet/sched/Makefile:43:obj-$(CONFIG_NET_SCH_TEQL)\t+= sch_teql.o\nnet/sched/Makefile-44-obj-$(CONFIG_NET_SCH_PRIO)\t+= sch_prio.o\n"
}
5/2 2026/06/30 23:31 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 3300
							output: 32
							thoughts: 84

Thoughts: 
**Fuzzing Strategy for TEQL Transmitter Function**

Okay, so I'm looking at this change, specifically the modifications to the `teql_master_xmit` function, which is linked to the `NET_SCH_TEQL` configuration option. From what I can see, this is a functional change involving some locking and RCU updates. Given that, this is prime territory for fuzzing, absolutely. The target symbol is definitely `teql_master_xmit`, and the `NET_SCH_TEQL` configuration needs to be enabled for testing.

I should probably double-check if there are any other related configurations that might also be relevant during fuzzing, just to ensure I'm covering all the bases. I don't want to miss anything.

6/2 2026/06/30 23:31 tool grepper
0m Args: 
{
  "Expression": "NET_SCH_TEQL",
  "PathPrefix": "net/sched/Kconfig"
}

Results: 
{
  "Output": "net/sched/Kconfig=111=config NET_SCH_SFQ\n--\nnet/sched/Kconfig-121-\nnet/sched/Kconfig:122:config NET_SCH_TEQL\nnet/sched/Kconfig-123-\ttristate \"True Link Equalizer (TEQL)\"\n"
}
7/2 2026/06/30 23:31 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 3668
							output: 100
							thoughts: 22

Thoughts: 
Okay, here's the summary, assuming I'm the expert thinking through this:

**Confirming the Configuration**

Alright, yep, that's it. *NET_SCH_TEQL* – that's the configuration setting I was looking for. Now that I've nailed that down, I'm ready to move forward. Time to get this set up correctly and record the results so that I can analyze them later.

8/2 2026/06/30 23:31 tool set-results
0m Args: 
{
  "EnableConfigs": [
    "NET_SCH_TEQL"
  ],
  "FocusSymbols": [
    "teql_master_xmit"
  ],
  "Reasoning": "The patch modifies the locking and RCU primitives in the teql_master_xmit function of the True Link Equalizer (TEQL) scheduler. This is a functional change that alters the execution flow and synchronization, so it should be fuzzed.",
  "WorthFuzzing": true
}

Results: 
{
  "EnableConfigs": [
    "NET_SCH_TEQL"
  ],
  "FocusSymbols": [
    "teql_master_xmit"
  ],
  "Reasoning": "The patch modifies the locking and RCU primitives in the teql_master_xmit function of the True Link Equalizer (TEQL) scheduler. This is a functional change that alters the execution flow and synchronization, so it should be fuzzed.",
  "WorthFuzzing": true
}
LLM Calls Summary:
Total Calls Total Tokens Avg Tokens Total Duration (Seconds) Avg Duration (Seconds)
Tool Calls Summary:
Total Calls Total Duration (Seconds) Avg Duration (Seconds)