From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:48804 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751496AbeANOng (ORCPT ); Sun, 14 Jan 2018 09:43:36 -0500 From: Coly Li To: linux-bcache@vger.kernel.org Cc: linux-block@vger.kernel.org, Coly Li , Michael Lyle , Hannes Reinecke , Junhui Tang Subject: [PATCH v3 03/13] bcache: set task properly in allocator_wait() Date: Sun, 14 Jan 2018 22:42:26 +0800 Message-Id: <20180114144236.28213-4-colyli@suse.de> In-Reply-To: <20180114144236.28213-1-colyli@suse.de> References: <20180114144236.28213-1-colyli@suse.de> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org 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 Cc: Michael Lyle Cc: Hannes Reinecke Cc: Junhui Tang --- 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