lkml.org 
[lkml]   [2011]   [Aug]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 06/16] freezer: make exiting tasks properly unfreezable
Date
There's no point in freezing an exiting task.  The current code
seemingly tries that by calling clear_freeze_flag() from exit_mm() but
it's racy as freeze might happen afterwards.

This patch removes the racy clear_freeze_flag() makes do_exit() set
PF_NOFREEZE after PTRACE_EVENT_EXIT, after which freezing doesn't make
sense.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
kernel/exit.c | 8 ++++++--
kernel/power/process.c | 3 +--
2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/kernel/exit.c b/kernel/exit.c
index 2913b35..ac58259 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -679,8 +679,6 @@ static void exit_mm(struct task_struct * tsk)
tsk->mm = NULL;
up_read(&mm->mmap_sem);
enter_lazy_tlb(mm, current);
- /* We don't want this task to be frozen prematurely */
- clear_freeze_flag(tsk);
if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
atomic_dec(&mm->oom_disable_count);
task_unlock(tsk);
@@ -915,6 +913,12 @@ NORET_TYPE void do_exit(long code)

ptrace_event(PTRACE_EVENT_EXIT, code);

+ /*
+ * With ptrace notification done, there's no point in freezing from
+ * here on. Disallow freezing.
+ */
+ current->flags |= PF_NOFREEZE;
+
validate_creds_for_do_exit(tsk);

/*
diff --git a/kernel/power/process.c b/kernel/power/process.c
index bec09c3..ddfaba4 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -25,8 +25,7 @@
static inline int freezable(struct task_struct * p)
{
if ((p == current) ||
- (p->flags & PF_NOFREEZE) ||
- (p->exit_state != 0))
+ (p->flags & PF_NOFREEZE))
return 0;
return 1;
}
--
1.7.6


\
 
 \ /
  Last update: 2011-08-19 16:21    [from the cache]
©2003-2011 Jasper Spaans