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| author | Tejun Heo <tj@kernel.org> | 2011-11-21 12:32:24 -0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2011-11-21 12:32:24 -0800 |
| commit | 85f1d476653f52c97ca75466b2494e67c1cbd25d (patch) | |
| tree | a1839143272cc4e6593e5d4c97e8a3c39aed08ff /kernel | |
| parent | 6907483b4e803a20f0b48cc9afa3817420ce61c5 (diff) | |
| download | lwn-85f1d476653f52c97ca75466b2494e67c1cbd25d.tar.gz lwn-85f1d476653f52c97ca75466b2494e67c1cbd25d.zip | |
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>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/freezer.c | 3 | ||||
| -rw-r--r-- | kernel/power/process.c | 16 |
2 files changed, 3 insertions, 16 deletions
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; |