From: Tejun Heo <tj@kernel.org>
To: rjw@sisk.pl, paul@paulmenage.org, linux-kernel@vger.kernel.org,
linux-pm@vger.kernel.org
Cc: arnd@arndb.de, oleg@redhat.com, matthltc@us.ibm.com,
Tejun Heo <tj@kernel.org>
Subject: [PATCH 10/17] freezer: test freezable conditions while holding freezer_lock
Date: Mon, 31 Oct 2011 12:05:21 -0700 [thread overview]
Message-ID: <1320087928-32307-11-git-send-email-tj@kernel.org> (raw)
In-Reply-To: <1320087928-32307-1-git-send-email-tj@kernel.org>
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>
---
kernel/freezer.c | 3 ++-
kernel/power/process.c | 16 +---------------
2 files changed, 3 insertions(+), 16 deletions(-)
diff --git a/kernel/freezer.c b/kernel/freezer.c
index 05afd68..5c911c0 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 e6e2739..e59676f 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;
--
1.7.3.1
next prev parent reply other threads:[~2011-10-31 19:08 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-31 19:05 [PATCHSET pm] freezer: fix various bugs and simplify implementation, take#2 Tejun Heo
2011-10-31 19:05 ` [PATCH 01/17] freezer: fix current->state restoration race in refrigerator() Tejun Heo
2011-10-31 19:05 ` [PATCH 02/17] freezer: don't unnecessarily set PF_NOFREEZE explicitly Tejun Heo
2011-10-31 19:05 ` [PATCH 03/17] freezer: unexport refrigerator() and update try_to_freeze() slightly Tejun Heo
2011-10-31 19:05 ` [PATCH 04/17] freezer: implement and use kthread_freezable_should_stop() Tejun Heo
2011-10-31 19:05 ` [PATCH 05/17] freezer: rename thaw_process() to __thaw_task() and simplify the implementation Tejun Heo
2011-11-06 12:04 ` Srivatsa S. Bhat
2011-11-06 16:51 ` Tejun Heo
2011-11-06 17:10 ` Srivatsa S. Bhat
2011-10-31 19:05 ` [PATCH 06/17] freezer: remove racy clear_freeze_flag() and set PF_NOFREEZE on dead tasks Tejun Heo
2011-10-31 19:05 ` [PATCH 07/17] freezer: don't distinguish nosig tasks on thaw Tejun Heo
2011-10-31 19:05 ` [PATCH 08/17] freezer: use dedicated lock instead of task_lock() + memory barrier Tejun Heo
2011-10-31 19:05 ` [PATCH 09/17] freezer: make freezing indicate freeze condition in effect Tejun Heo
2011-10-31 19:05 ` Tejun Heo [this message]
2011-10-31 19:05 ` [PATCH 11/17] freezer: kill PF_FREEZING Tejun Heo
2011-10-31 19:05 ` [PATCH 12/17] freezer: clean up freeze_processes() failure path Tejun Heo
2011-11-03 19:09 ` Srivatsa S. Bhat
2011-11-03 22:25 ` [PATCH UPDATED " Tejun Heo
2011-10-31 19:05 ` [PATCH 13/17] cgroup_freezer: prepare for removal of TIF_FREEZE Tejun Heo
2011-10-31 22:33 ` [PATCH UPDATED " Tejun Heo
2011-10-31 19:05 ` [PATCH 14/17] freezer: make freezing() test freeze conditions in effect instead " Tejun Heo
2011-10-31 22:34 ` [PATCH UPDATED " Tejun Heo
2011-10-31 19:05 ` [PATCH 15/17] freezer: remove now unused TIF_FREEZE Tejun Heo
2011-10-31 19:05 ` [PATCH 16/17] freezer: remove should_send_signal() and update frozen() Tejun Heo
2011-10-31 19:05 ` [PATCH 17/17] freezer: fix set_freezable[_with_signal]() race Tejun Heo
2011-10-31 22:34 ` [PATCH 18/17] freezer: restructure __refrigerator() Tejun Heo
2011-10-31 22:35 ` [PATCH 19/17] freezer: use lock_task_sighand() in fake_signal_wake_up() Tejun Heo
2011-10-31 22:35 ` [PATCH UPDATED 20/17] freezer: remove unused @sig_only from freeze_task() Tejun Heo
2011-10-31 22:40 ` [PATCHSET UPDATED pm] freezer: fix various bugs and simplify implementation, take#2 Tejun Heo
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