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authorOleg Nesterov <oleg@tv-sign.ru>2006-12-08 11:36:07 +0100
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-08 17:28:38 +0100
commit915935041281c64589e2b7fe38437be22567fb6f (patch)
treefef15e8442be8ab8c72439ff916855444a8e95b8 /fs/proc/array.c
parent[PATCH] tty: ->signal->tty locking (diff)
downloadlinux-915935041281c64589e2b7fe38437be22567fb6f.tar.xz
linux-915935041281c64589e2b7fe38437be22567fb6f.zip
[PATCH] do_task_stat(): don't take tty_mutex
->signal->tty is protected by ->siglock, no need to take the global tty_mutex. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to '')
-rw-r--r--fs/proc/array.c16
1 files changed, 4 insertions, 12 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 25e917fb4739..b0cd014a39bd 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -346,20 +346,13 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole)
sigemptyset(&sigcatch);
cutime = cstime = utime = stime = cputime_zero;
- mutex_lock(&tty_mutex);
rcu_read_lock();
if (lock_task_sighand(task, &flags)) {
struct signal_struct *sig = task->signal;
- struct tty_struct *tty = sig->tty;
-
- if (tty) {
- /*
- * sig->tty is not stable, but tty_mutex
- * protects us from release_dev(tty)
- */
- barrier();
- tty_pgrp = tty->pgrp;
- tty_nr = new_encode_dev(tty_devnum(tty));
+
+ if (sig->tty) {
+ tty_pgrp = sig->tty->pgrp;
+ tty_nr = new_encode_dev(tty_devnum(sig->tty));
}
num_threads = atomic_read(&sig->count);
@@ -395,7 +388,6 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole)
unlock_task_sighand(task, &flags);
}
rcu_read_unlock();
- mutex_unlock(&tty_mutex);
if (!whole || num_threads<2)
wchan = get_wchan(task);