From: Coly Li <colyli@suse.de>
To: linux-bcache@vger.kernel.org
Cc: linux-block@vger.kernel.org, Coly Li <colyli@suse.de>,
Michael Lyle <mlyle@lyle.org>, Hannes Reinecke <hare@suse.de>,
Junhui Tang <tang.junhui@zte.com.cn>
Subject: [PATCH v2 03/12] bcache: set task properly in allocator_wait()
Date: Sun, 14 Jan 2018 01:10:41 +0800 [thread overview]
Message-ID: <20180113171050.22467-4-colyli@suse.de> (raw)
In-Reply-To: <20180113171050.22467-1-colyli@suse.de>
Kernel thread routine bch_allocator_thread() references macro
allocator_wait() to wait for a condition or quit to do_exit()
when kthread_should_stop() is true. Here is the code block,
284 while (1) { \
285 set_current_state(TASK_INTERRUPTIBLE); \
286 if (cond) \
287 break; \
288 \
289 mutex_unlock(&(ca)->set->bucket_lock); \
290 if (kthread_should_stop()) \
291 return 0; \
292 \
293 schedule(); \
294 mutex_lock(&(ca)->set->bucket_lock); \
295 } \
296 __set_current_state(TASK_RUNNING); \
At line 285, task state is set to TASK_INTERRUPTIBLE, if at line 290
kthread_should_stop() is true, the kernel thread will terminate and return
to kernel/kthread.s:kthread(), then calls do_exit() with TASK_INTERRUPTIBLE
state. This is not a suggested behavior and a warning message will be
reported by might_sleep() in do_exit() code path: "WARNING: do not call
blocking ops when !TASK_RUNNING; state=1 set at [xxxx]".
This patch fixes this problem by setting task state to TASK_RUNNING if
kthread_should_stop() is true and before kernel thread returns back to
kernel/kthread.s:kthread().
Changelog:
v2: fix the race issue in v1 patch.
v1: initial buggy fix.
Signed-off-by: Coly Li <colyli@suse.de>
Cc: Michael Lyle <mlyle@lyle.org>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Junhui Tang <tang.junhui@zte.com.cn>
---
drivers/md/bcache/alloc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c
index 6cc6c0f9c3a9..458e1d38577d 100644
--- a/drivers/md/bcache/alloc.c
+++ b/drivers/md/bcache/alloc.c
@@ -287,8 +287,10 @@ do { \
break; \
\
mutex_unlock(&(ca)->set->bucket_lock); \
- if (kthread_should_stop()) \
+ if (kthread_should_stop()) { \
+ set_current_state(TASK_RUNNING); \
return 0; \
+ } \
\
schedule(); \
mutex_lock(&(ca)->set->bucket_lock); \
--
2.15.1
next prev parent reply other threads:[~2018-01-13 17:10 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-13 17:10 [PATCH v2 00/12] bcache: device failure handling improvement Coly Li
2018-01-13 17:10 ` [PATCH v2 01/12] bcache: set writeback_rate_update_seconds in range [1, 60] seconds Coly Li
2018-01-13 17:10 ` [PATCH v2 02/12] bcache: properly set task state in bch_writeback_thread() Coly Li
2018-01-13 17:10 ` Coly Li [this message]
2018-01-13 17:10 ` [PATCH v2 04/12] bcache: fix cached_dev->count usage for bch_cache_set_error() Coly Li
2018-01-13 17:10 ` [PATCH v2 05/12] bcache: stop dc->writeback_rate_update properly Coly Li
2018-01-13 17:10 ` [PATCH v2 06/12] bcache: set error_limit correctly Coly Li
2018-01-13 17:10 ` [PATCH v2 07/12] bcache: add CACHE_SET_IO_DISABLE to struct cache_set flags Coly Li
2018-01-13 17:10 ` [PATCH v2 08/12] bcache: stop all attached bcache devices for a retired cache set Coly Li
2018-01-13 17:10 ` [PATCH v2 09/12] bcache: fix inaccurate io state for detached bcache devices Coly Li
2018-01-13 17:10 ` [PATCH v2 10/12] bcache: add backing_request_endio() for bi_end_io of attached backing device I/O Coly Li
2018-01-13 17:10 ` [PATCH v2 11/12] bcache: add io_disable to struct cached_dev Coly Li
2018-01-13 17:10 ` [PATCH v2 12/12] bcache: stop bcache device when backing device is offline Coly Li
-- strict thread matches above, loose matches on Subject: below --
2018-01-13 17:01 [PATCH v2 00/12] bcache: device failure handling improvement Coly Li
2018-01-13 17:01 ` [PATCH v2 03/12] bcache: set task properly in allocator_wait() Coly Li
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