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| author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-10-02 02:18:54 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-02 07:57:24 -0700 |
| commit | b0fa9db6abdb2875a6d3069ddc6a2846a73fa5cd (patch) | |
| tree | 840fd70ce726f94ff389d97dd012e53ae02f1dcf /fs/proc | |
| parent | a593d6edeb0a5a2c6e6919b225cec668a375df52 (diff) | |
| download | op-kernel-dev-b0fa9db6abdb2875a6d3069ddc6a2846a73fa5cd.zip op-kernel-dev-b0fa9db6abdb2875a6d3069ddc6a2846a73fa5cd.tar.gz | |
[PATCH] proc: drop tasklist lock in task_state()
task_state() needs tasklist_lock to protect ->parent/->real_parent. However
task->parent points to nowhere only when the actions below happen in order
1) release_task(task)
2) release_task(task->parent)
3) a grace period passed
But 3) implies that the memory ops from 1) should be finished, so pid_alive()
can't be true in such a case.
Otherwise, we don't care if ->parent/->real_parent changes under us.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/array.c | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c index 35bd39d..25e917f 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -162,7 +162,7 @@ static inline char * task_state(struct task_struct *p, char *buffer) int g; struct fdtable *fdt = NULL; - read_lock(&tasklist_lock); + rcu_read_lock(); buffer += sprintf(buffer, "State:\t%s\n" "SleepAVG:\t%lu%%\n" @@ -174,14 +174,13 @@ static inline char * task_state(struct task_struct *p, char *buffer) "Gid:\t%d\t%d\t%d\t%d\n", get_task_state(p), (p->sleep_avg/1024)*100/(1020000000/1024), - p->tgid, - p->pid, pid_alive(p) ? p->group_leader->real_parent->tgid : 0, - pid_alive(p) && p->ptrace ? p->parent->pid : 0, + p->tgid, p->pid, + pid_alive(p) ? rcu_dereference(p->real_parent)->tgid : 0, + pid_alive(p) && p->ptrace ? rcu_dereference(p->parent)->pid : 0, p->uid, p->euid, p->suid, p->fsuid, p->gid, p->egid, p->sgid, p->fsgid); - read_unlock(&tasklist_lock); + task_lock(p); - rcu_read_lock(); if (p->files) fdt = files_fdtable(p->files); buffer += sprintf(buffer, |
