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authorTejun Heo <tj@kernel.org>2011-11-23 09:28:17 -0800
committerTejun Heo <tj@kernel.org>2011-11-23 09:28:17 -0800
commit34b087e48367c252e343c2f8de65676a78af1e4a (patch)
treefbe94bad0a3073c6f4231752fba99c6bc8702277 /kernel/freezer.c
parentadfa543e7314b36ac55a40019977de6e47946dd7 (diff)
downloadvexpress-lsk-34b087e48367c252e343c2f8de65676a78af1e4a.tar.gz
freezer: kill unused set_freezable_with_signal()
There's no in-kernel user of set_freezable_with_signal() left. Mixing TIF_SIGPENDING with kernel threads can lead to nasty corner cases as kernel threads never travel signal delivery path on their own. e.g. the current implementation is buggy in the cancelation path of __thaw_task(). It calls recalc_sigpending_and_wake() in an attempt to clear TIF_SIGPENDING but the function never clears it regardless of sigpending state. This means that signallable freezable kthreads may continue executing with !freezing() && stuck TIF_SIGPENDING, which can be troublesome. This patch removes set_freezable_with_signal() along with PF_FREEZER_NOSIG and recalc_sigpending*() calls in freezer. User tasks get TIF_SIGPENDING, kernel tasks get woken up and the spurious sigpending is dealt with in the usual signal delivery path. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'kernel/freezer.c')
-rw-r--r--kernel/freezer.c27
1 files changed, 6 insertions, 21 deletions
diff --git a/kernel/freezer.c b/kernel/freezer.c
index 2589a61de44..9815b8d1eed 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -39,7 +39,7 @@ bool freezing_slow_path(struct task_struct *p)
if (pm_nosig_freezing || cgroup_freezing(p))
return true;
- if (pm_freezing && !(p->flags & PF_FREEZER_NOSIG))
+ if (pm_freezing && !(p->flags & PF_KTHREAD))
return true;
return false;
@@ -72,10 +72,6 @@ bool __refrigerator(bool check_kthr_stop)
schedule();
}
- spin_lock_irq(&current->sighand->siglock);
- recalc_sigpending(); /* We sent fake signal, clean it up */
- spin_unlock_irq(&current->sighand->siglock);
-
pr_debug("%s left refrigerator\n", current->comm);
/*
@@ -120,7 +116,7 @@ bool freeze_task(struct task_struct *p)
return false;
}
- if (!(p->flags & PF_FREEZER_NOSIG)) {
+ if (!(p->flags & PF_KTHREAD)) {
fake_signal_wake_up(p);
/*
* fake_signal_wake_up() goes through p's scheduler
@@ -145,28 +141,19 @@ void __thaw_task(struct task_struct *p)
* be visible to @p as waking up implies wmb. Waking up inside
* freezer_lock also prevents wakeups from leaking outside
* refrigerator.
- *
- * If !FROZEN, @p hasn't reached refrigerator, recalc sigpending to
- * avoid leaving dangling TIF_SIGPENDING behind.
*/
spin_lock_irqsave(&freezer_lock, flags);
- if (frozen(p)) {
+ if (frozen(p))
wake_up_process(p);
- } else {
- spin_lock(&p->sighand->siglock);
- recalc_sigpending_and_wake(p);
- spin_unlock(&p->sighand->siglock);
- }
spin_unlock_irqrestore(&freezer_lock, flags);
}
/**
- * __set_freezable - make %current freezable
- * @with_signal: do we want %TIF_SIGPENDING for notification too?
+ * set_freezable - make %current freezable
*
* Mark %current freezable and enter refrigerator if necessary.
*/
-bool __set_freezable(bool with_signal)
+bool set_freezable(void)
{
might_sleep();
@@ -177,10 +164,8 @@ bool __set_freezable(bool with_signal)
*/
spin_lock_irq(&freezer_lock);
current->flags &= ~PF_NOFREEZE;
- if (with_signal)
- current->flags &= ~PF_FREEZER_NOSIG;
spin_unlock_irq(&freezer_lock);
return try_to_freeze();
}
-EXPORT_SYMBOL(__set_freezable);
+EXPORT_SYMBOL(set_freezable);