evie/android_kernel_oneplus_msm8998
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lock_task_sighand: add rcu lock/unlock

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Most of the callers of lock_task_sighand() doesn't actually need rcu_lock().
lock_task_sighand() needs it only to safely play with tsk->sighand, it can
take the lock itself.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2008-04-30 00:52:37 -07:00 • committed by Linus Torvalds
parent bfc4b0890a
commit 1406f2d321
1 changed files with 2 additions and 3 deletions
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5
kernel/signal.c
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@ -971,13 +971,11 @@ int __fatal_signal_pending(struct task_struct *tsk)
} }
EXPORT_SYMBOL(__fatal_signal_pending); EXPORT_SYMBOL(__fatal_signal_pending);
/*
* Must be called under rcu_read_lock() or with tasklist_lock read-held.
*/
struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags) struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
{ {
struct sighand_struct *sighand; struct sighand_struct *sighand;
rcu_read_lock();
for (;;) { for (;;) {
sighand = rcu_dereference(tsk->sighand); sighand = rcu_dereference(tsk->sighand);
if (unlikely(sighand == NULL)) if (unlikely(sighand == NULL))
@ -988,6 +986,7 @@ struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long
break; break;
spin_unlock_irqrestore(&sighand->siglock, *flags); spin_unlock_irqrestore(&sighand->siglock, *flags);
} }
rcu_read_unlock();
return sighand; return sighand;
} }