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authorTejun Heo <tj@kernel.org>2011-11-21 12:32:23 -0800
committerTejun Heo <tj@kernel.org>2011-11-21 12:32:23 -0800
commit8a32c441c1609f80e55df75422324a1151208f40 (patch)
tree73884b06cc2db3ea155af9a88815bb5105a4473e /fs
parenta0acae0e886d44bd5ce6d2f173c1ace0fcf0d9f6 (diff)
downloadop-kernel-dev-8a32c441c1609f80e55df75422324a1151208f40.zip
op-kernel-dev-8a32c441c1609f80e55df75422324a1151208f40.tar.gz
freezer: implement and use kthread_freezable_should_stop()
Writeback and thinkpad_acpi have been using thaw_process() to prevent deadlock between the freezer and kthread_stop(); unfortunately, this is inherently racy - nothing prevents freezing from happening between thaw_process() and kthread_stop(). This patch implements kthread_freezable_should_stop() which enters refrigerator if necessary but is guaranteed to return if kthread_stop() is invoked. Both thaw_process() users are converted to use the new function. Note that this deadlock condition exists for many of freezable kthreads. They need to be converted to use the new should_stop or freezable workqueue. Tested with synthetic test case. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Henrique de Moraes Holschuh <ibm-acpi@hmh.eng.br> Cc: Jens Axboe <axboe@kernel.dk> Cc: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/fs-writeback.c4
1 files changed, 1 insertions, 3 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 73c3992..271fde5 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -947,7 +947,7 @@ int bdi_writeback_thread(void *data)
trace_writeback_thread_start(bdi);
- while (!kthread_should_stop()) {
+ while (!kthread_freezable_should_stop(NULL)) {
/*
* Remove own delayed wake-up timer, since we are already awake
* and we'll take care of the preriodic write-back.
@@ -977,8 +977,6 @@ int bdi_writeback_thread(void *data)
*/
schedule();
}
-
- try_to_freeze();
}
/* Flush any work that raced with us exiting */
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