Messages in this thread Patch in this message |  | | From | Paul Gortmaker <> | Subject | [v2.6.34-stable 41/77] genirq: Fix race condition when stopping the irq thread | Date | Tue, 8 Jan 2013 18:35:20 -0500 |
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From: Ido Yariv <ido@wizery.com>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. -------------------
commit 550acb19269d65f32e9ac4ddb26c2b2070e37f1c upstream.
In irq_wait_for_interrupt(), the should_stop member is verified before setting the task's state to TASK_INTERRUPTIBLE and calling schedule(). In case kthread_stop sets should_stop and wakes up the process after should_stop is checked by the irq thread but before the task's state is changed, the irq thread might never exit:
kthread_stop irq_wait_for_interrupt ------------ ----------------------
... ... while (!kthread_should_stop()) { kthread->should_stop = 1; wake_up_process(k); wait_for_completion(&kthread->exited); ... set_current_state(TASK_INTERRUPTIBLE);
...
schedule(); }
Fix this by checking if the thread should stop after modifying the task's state.
[ tglx: Simplified it a bit ]
Signed-off-by: Ido Yariv <ido@wizery.com> Link: http://lkml.kernel.org/r/1322740508-22640-1-git-send-email-ido@wizery.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- kernel/irq/manage.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 9080985..8668523 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -479,8 +479,9 @@ static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id) static int irq_wait_for_interrupt(struct irqaction *action) { + set_current_state(TASK_INTERRUPTIBLE); + while (!kthread_should_stop()) { - set_current_state(TASK_INTERRUPTIBLE); if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags)) { @@ -488,7 +489,9 @@ static int irq_wait_for_interrupt(struct irqaction *action) return 0; } schedule(); + set_current_state(TASK_INTERRUPTIBLE); } + __set_current_state(TASK_RUNNING); return -1; } -- 1.7.12.1
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