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| author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-03-28 16:11:14 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-28 18:36:42 -0800 |
| commit | 7001510d0cbf51ad202dd2d0744f54104285cbb9 (patch) | |
| tree | 1df2a6930c460c12026231634b86d14b153a4a86 | |
| parent | a9e88e84b5245da0a1dadb6ccca70ae84e93ccf6 (diff) | |
| download | op-kernel-dev-7001510d0cbf51ad202dd2d0744f54104285cbb9.zip op-kernel-dev-7001510d0cbf51ad202dd2d0744f54104285cbb9.tar.gz | |
[PATCH] copy_process: cleanup bad_fork_cleanup_sighand
The only caller of exit_sighand(tsk) is copy_process's error path. We can
call __exit_sighand() directly and kill exit_sighand().
This 'tsk' was not yet registered in pid_hash[] or init_task.tasks, it has no
external references, nobody can see it, and
IF (clone_flags & CLONE_SIGHAND)
At least 'current' has a reference to ->sighand, this
means atomic_dec_and_test(sighand->count) can't be true.
ELSE
Nobody can see this ->sighand, this means we can free it
without any locking.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | include/linux/sched.h | 1 | ||||
| -rw-r--r-- | kernel/fork.c | 3 | ||||
| -rw-r--r-- | kernel/signal.c | 14 |
3 files changed, 2 insertions, 16 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index ca1fd31..69c2a1e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1151,7 +1151,6 @@ extern void exit_thread(void); extern void exit_files(struct task_struct *); extern void exit_signal(struct task_struct *); extern void __exit_signal(struct task_struct *); -extern void exit_sighand(struct task_struct *); extern void __exit_sighand(struct task_struct *); extern void exit_itimers(struct signal_struct *); diff --git a/kernel/fork.c b/kernel/fork.c index 33ffb5b..8a46ad5 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1208,7 +1208,8 @@ bad_fork_cleanup_mm: bad_fork_cleanup_signal: exit_signal(p); bad_fork_cleanup_sighand: - exit_sighand(p); + if (p->sighand) + __exit_sighand(p); bad_fork_cleanup_fs: exit_fs(p); /* blocking */ bad_fork_cleanup_files: diff --git a/kernel/signal.c b/kernel/signal.c index c5b65aa..1d7f446 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -336,20 +336,6 @@ void __exit_sighand(struct task_struct *tsk) kmem_cache_free(sighand_cachep, sighand); } -void exit_sighand(struct task_struct *tsk) -{ - write_lock_irq(&tasklist_lock); - rcu_read_lock(); - if (tsk->sighand != NULL) { - struct sighand_struct *sighand = rcu_dereference(tsk->sighand); - spin_lock(&sighand->siglock); - __exit_sighand(tsk); - spin_unlock(&sighand->siglock); - } - rcu_read_unlock(); - write_unlock_irq(&tasklist_lock); -} - /* * This function expects the tasklist_lock write-locked. */ |
