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[PATCH] sys_times: don't take tasklist_lock

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sys_times: don't take tasklist_lock

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Oleg Nesterov 2006-03-28 16:11:21 -08:00 committed by Linus Torvalds
parent 5876700cd3
commit 7d7185c818
1 changed files with 1 additions and 12 deletions
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13
kernel/sys.c
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@ -1206,7 +1206,7 @@ asmlinkage long sys_times(struct tms __user * tbuf)
struct task_struct *t;
cputime_t utime, stime, cutime, cstime;
read_lock(&tasklist_lock);
spin_lock_irq(&tsk->sighand->siglock);
utime = tsk->signal->utime;
stime = tsk->signal->stime;
t = tsk;
@ -1216,20 +1216,9 @@ asmlinkage long sys_times(struct tms __user * tbuf)
t = next_thread(t);
} while (t != tsk);
/*
* While we have tasklist_lock read-locked, no dying thread
* can be updating current->signal->[us]time. Instead,
* we got their counts included in the live thread loop.
* However, another thread can come in right now and
* do a wait call that updates current->signal->c[us]time.
* To make sure we always see that pair updated atomically,
* we take the siglock around fetching them.
*/
spin_lock_irq(&tsk->sighand->siglock);
cutime = tsk->signal->cutime;
cstime = tsk->signal->cstime;
spin_unlock_irq(&tsk->sighand->siglock);
read_unlock(&tasklist_lock);
tmp.tms_utime = cputime_to_clock_t(utime);
tmp.tms_stime = cputime_to_clock_t(stime);