From: Tejun Heo <tj@kernel.org>
Date: Mon, 21 Nov 2011 20:32:24 +0000 (-0800)
Subject: freezer: test freezable conditions while holding freezer_lock
X-Git-Tag: v3.3-rc1~148^2~24^2~14
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=85f1d476653f52c97ca75466b2494e67c1cbd25d;p=linux.git
freezer: test freezable conditions while holding freezer_lock
try_to_freeze_tasks() and thaw_processes() use freezable() and
frozen() as preliminary tests before initiating operations on a task.
These are done without any synchronization and hinder with
synchronization cleanup without any real performance benefits.
In try_to_freeze_tasks(), open code self test and move PF_NOFREEZE and
frozen() tests inside freezer_lock in freeze_task().
thaw_processes() can simply drop freezable() test as frozen() test in
__thaw_task() is enough.
Note: This used to be a part of larger patch to fix set_freezable()
race. Separated out to satisfy ordering among dependent fixes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
---
diff --git a/kernel/freezer.c b/kernel/freezer.c
index a8822be43da0..a257ecd37c48 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -109,7 +109,8 @@ bool freeze_task(struct task_struct *p, bool sig_only)
spin_lock_irqsave(&freezer_lock, flags);
- if (sig_only && !should_send_signal(p))
+ if ((p->flags & PF_NOFREEZE) ||
+ (sig_only && !should_send_signal(p)))
goto out_unlock;
if (frozen(p))
diff --git a/kernel/power/process.c b/kernel/power/process.c
index e6e2739190b5..e59676f5811d 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -22,14 +22,6 @@
*/
#define TIMEOUT (20 * HZ)
-static inline int freezable(struct task_struct * p)
-{
- if ((p == current) ||
- (p->flags & PF_NOFREEZE))
- return 0;
- return 1;
-}
-
static int try_to_freeze_tasks(bool sig_only)
{
struct task_struct *g, *p;
@@ -52,10 +44,7 @@ static int try_to_freeze_tasks(bool sig_only)
todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
- if (frozen(p) || !freezable(p))
- continue;
-
- if (!freeze_task(p, sig_only))
+ if (p == current || !freeze_task(p, sig_only))
continue;
/*
@@ -181,9 +170,6 @@ void thaw_processes(void)
read_lock(&tasklist_lock);
do_each_thread(g, p) {
- if (!freezable(p))
- continue;
-
if (cgroup_freezing_or_frozen(p))
continue;