[v1] md/raid5-cache: fix a deadlock in r5l_exit_log()

[PATCH -next 0/2] md/raid5-cache: fix a deadlock in r5l_exit_log()

Yu Kuai posted 2 patches 2 years, 7 months ago

Diff against v2 v3
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drivers/md/raid5-cache.c | 24 ++++++++++--------------
1 file changed, 10 insertions(+), 14 deletions(-)

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[PATCH -next 0/2] md/raid5-cache: fix a deadlock in r5l_exit_log()

Posted by Yu Kuai 2 years, 7 months ago

From: Yu Kuai <yukuai3@huawei.com>

Commit b13015af94cf ("md/raid5-cache: Clear conf->log after finishing
work") introduce a new problem:

// caller hold reconfig_mutex
r5l_exit_log
 flush_work(&log->disable_writeback_work)
			r5c_disable_writeback_async
			 wait_event
			  /*
			   * conf->log is not NULL, and mddev_trylock()
			   * will fail, wait_event() can never pass.
			   */
 conf->log = NULL

patch 1 revert this patch, an patch 2 fix the original problem in a
different way.

Noted this problem is just found by code review, and I think this is
probably the reason that some mdadm tests is broken.

Yu Kuai (2):
  md/raid5-cache: Revert "md/raid5-cache: Clear conf->log after
    finishing work"
  md/raid5-cache: fix null-ptr-deref in r5l_reclaim_thread()

 drivers/md/raid5-cache.c | 24 ++++++++++--------------
 1 file changed, 10 insertions(+), 14 deletions(-)

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2.39.2