next_tgid() accept pid namespace as an argument, but it is never changes during readdir (which would be unthinkable thing to do anyway). Move it inside iterator type and hide from using directly. Signed-off-by: Alexey Dobriyan --- fs/proc/base.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 4eec684baca9..7c1089226a47 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -3540,8 +3540,10 @@ struct dentry *proc_pid_lookup(struct dentry *dentry, unsigned int flags) struct tgid_iter { unsigned int tgid; struct task_struct *task; + struct pid_namespace *pid_ns; }; -static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter iter) + +static struct tgid_iter next_tgid(struct tgid_iter iter) { struct pid *pid; @@ -3550,9 +3552,9 @@ static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter ite rcu_read_lock(); retry: iter.task = NULL; - pid = find_ge_pid(iter.tgid, ns); + pid = find_ge_pid(iter.tgid, iter.pid_ns); if (pid) { - iter.tgid = pid_nr_ns(pid, ns); + iter.tgid = pid_nr_ns(pid, iter.pid_ns); iter.task = pid_task(pid, PIDTYPE_TGID); if (!iter.task) { iter.tgid += 1; @@ -3571,7 +3573,7 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx) { struct tgid_iter iter; struct proc_fs_info *fs_info = proc_sb_info(file_inode(file)->i_sb); - struct pid_namespace *ns = proc_pid_ns(file_inode(file)->i_sb); + struct pid_namespace *pid_ns = proc_pid_ns(file_inode(file)->i_sb); loff_t pos = ctx->pos; if (pos >= PID_MAX_LIMIT + TGID_OFFSET) @@ -3589,9 +3591,10 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx) } iter.tgid = pos - TGID_OFFSET; iter.task = NULL; - for (iter = next_tgid(ns, iter); + iter.pid_ns = pid_ns; + for (iter = next_tgid(iter); iter.task; - iter.tgid += 1, iter = next_tgid(ns, iter)) { + iter.tgid += 1, iter = next_tgid(iter)) { char name[10 + 1]; unsigned int len; -- 2.51.2 * deduplicate "iter.tgid += 1" line, it is done once inside next_tgid() itself and second time inside "for" loop * deduplicate next_tgid() call itself with different loop style: auto it = make_xxx_iter(); while (next_xxx(&it)) { } gcc seems to inline it twice in the original code: $ ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux add/remove: 0/1 grow/shrink: 1/0 up/down: 100/-245 (-145) Function old new delta proc_pid_readdir 531 631 +100 next_tgid 245 - -245 But if there is only one call, it doesn't matter if it is inlined or not! * make tgid_iter.pid_ns const it never changes during readdir, returning instance + C99 initializer make it possible, * rename "iter" to "it", this is what another language seems to be doing. * limit declaration scope to prevent problems (in general). --- fs/proc/base.c | 69 ++++++++++++++++++++++++++++---------------------- 1 file changed, 39 insertions(+), 30 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 7c1089226a47..ddf5e16c795b 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -3535,35 +3535,48 @@ struct dentry *proc_pid_lookup(struct dentry *dentry, unsigned int flags) /* * Find the first task with tgid >= tgid - * */ struct tgid_iter { unsigned int tgid; struct task_struct *task; - struct pid_namespace *pid_ns; + struct pid_namespace *const pid_ns; }; -static struct tgid_iter next_tgid(struct tgid_iter iter) +static +struct tgid_iter +make_tgid_iter(unsigned int init_tgid, struct pid_namespace *pid_ns) { - struct pid *pid; + return (struct tgid_iter){ + /* See preincrement below. */ + .tgid = init_tgid - 1, + .pid_ns = pid_ns, + }; +} + +static bool next_tgid(struct tgid_iter *it) +{ + if (it->task) { + put_task_struct(it->task); + it->task = NULL; + } - if (iter.task) - put_task_struct(iter.task); rcu_read_lock(); -retry: - iter.task = NULL; - pid = find_ge_pid(iter.tgid, iter.pid_ns); - if (pid) { - iter.tgid = pid_nr_ns(pid, iter.pid_ns); - iter.task = pid_task(pid, PIDTYPE_TGID); - if (!iter.task) { - iter.tgid += 1; - goto retry; + while (1) { + it->tgid += 1; + struct pid *pid = find_ge_pid(it->tgid, it->pid_ns); + if (pid) { + it->tgid = pid_nr_ns(pid, it->pid_ns); + it->task = pid_task(pid, PIDTYPE_TGID); + if (it->task) { + get_task_struct(it->task); + rcu_read_unlock(); + return true; + } + } else { + rcu_read_unlock(); + return false; } - get_task_struct(iter.task); } - rcu_read_unlock(); - return iter; } #define TGID_OFFSET (FIRST_PROCESS_ENTRY + 2) @@ -3571,7 +3584,6 @@ static struct tgid_iter next_tgid(struct tgid_iter iter) /* for the /proc/ directory itself, after non-process stuff has been done */ int proc_pid_readdir(struct file *file, struct dir_context *ctx) { - struct tgid_iter iter; struct proc_fs_info *fs_info = proc_sb_info(file_inode(file)->i_sb); struct pid_namespace *pid_ns = proc_pid_ns(file_inode(file)->i_sb); loff_t pos = ctx->pos; @@ -3589,24 +3601,21 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx) return 0; ctx->pos = pos = pos + 1; } - iter.tgid = pos - TGID_OFFSET; - iter.task = NULL; - iter.pid_ns = pid_ns; - for (iter = next_tgid(iter); - iter.task; - iter.tgid += 1, iter = next_tgid(iter)) { + + auto it = make_tgid_iter(pos - TGID_OFFSET, pid_ns); + while (next_tgid(&it)) { char name[10 + 1]; unsigned int len; cond_resched(); - if (!has_pid_permissions(fs_info, iter.task, HIDEPID_INVISIBLE)) + if (!has_pid_permissions(fs_info, it.task, HIDEPID_INVISIBLE)) continue; - len = snprintf(name, sizeof(name), "%u", iter.tgid); - ctx->pos = iter.tgid + TGID_OFFSET; + len = snprintf(name, sizeof(name), "%u", it.tgid); + ctx->pos = it.tgid + TGID_OFFSET; if (!proc_fill_cache(file, ctx, name, len, - proc_pid_instantiate, iter.task, NULL)) { - put_task_struct(iter.task); + proc_pid_instantiate, it.task, NULL)) { + put_task_struct(it.task); return 0; } } -- 2.51.2