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authorTejun Heo <tj@kernel.org>2011-11-21 15:32:24 -0500
committerTejun Heo <tj@kernel.org>2011-11-21 15:32:24 -0500
commit85f1d476653f52c97ca75466b2494e67c1cbd25d (patch)
treea1839143272cc4e6593e5d4c97e8a3c39aed08ff /kernel/power
parent6907483b4e803a20f0b48cc9afa3817420ce61c5 (diff)
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/power')
-rw-r--r--kernel/power/process.c16
1 files changed, 1 insertions, 15 deletions
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 @@
22 */ 22 */
23#define TIMEOUT (20 * HZ) 23#define TIMEOUT (20 * HZ)
24 24
25static inline int freezable(struct task_struct * p)
26{
27 if ((p == current) ||
28 (p->flags & PF_NOFREEZE))
29 return 0;
30 return 1;
31}
32
33static int try_to_freeze_tasks(bool sig_only) 25static int try_to_freeze_tasks(bool sig_only)
34{ 26{
35 struct task_struct *g, *p; 27 struct task_struct *g, *p;
@@ -52,10 +44,7 @@ static int try_to_freeze_tasks(bool sig_only)
52 todo = 0; 44 todo = 0;
53 read_lock(&tasklist_lock); 45 read_lock(&tasklist_lock);
54 do_each_thread(g, p) { 46 do_each_thread(g, p) {
55 if (frozen(p) || !freezable(p)) 47 if (p == current || !freeze_task(p, sig_only))
56 continue;
57
58 if (!freeze_task(p, sig_only))
59 continue; 48 continue;
60 49
61 /* 50 /*
@@ -181,9 +170,6 @@ void thaw_processes(void)
181 170
182 read_lock(&tasklist_lock); 171 read_lock(&tasklist_lock);
183 do_each_thread(g, p) { 172 do_each_thread(g, p) {
184 if (!freezable(p))
185 continue;
186
187 if (cgroup_freezing_or_frozen(p)) 173 if (cgroup_freezing_or_frozen(p))
188 continue; 174 continue;
189 175