From mboxrd@z Thu Jan 1 00:00:00 1970 From: Song Liu Subject: [PATCH v2] md/r5cache: call mddev_lock/unlock() in r5c_journal_mode_show Date: Tue, 8 Aug 2017 22:56:52 -0700 Message-ID: <20170809055652.3114509-1-songliubraving@fb.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org, shli@kernel.org Cc: fengguang.wu@intel.com, sfr@canb.auug.org.au, Song Liu , shli@fb.com, neilb@suse.com, kernel-team@fb.com, dan.j.williams@intel.com, hch@infradead.org, jes.sorensen@gmail.com List-Id: linux-raid.ids In r5c_journal_mode_show(), it is necessary to call mddev_lock() before accessing conf and conf->log. Otherwise, the conf->log may change (and become NULL). Signed-off-by: Song Liu Reported-by: Stephen Rothwell Reported-by: kbuild test robot --- drivers/md/raid5-cache.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c index 2dcbafa..b6f3702 100644 --- a/drivers/md/raid5-cache.c +++ b/drivers/md/raid5-cache.c @@ -2529,11 +2529,19 @@ static void r5l_write_super(struct r5l_log *log, sector_t cp) static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page) { - struct r5conf *conf = mddev->private; + struct r5conf *conf; int ret; + int err; - if (!conf->log) + err = mddev_lock(mddev); + if (err) + return err; + + conf = mddev->private; + if (!conf || !conf->log) { + mddev_unlock(mddev); return 0; + } switch (conf->log->r5c_journal_mode) { case R5C_JOURNAL_MODE_WRITE_THROUGH: @@ -2551,6 +2559,7 @@ static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page) default: ret = 0; } + mddev_unlock(mddev); return ret; } -- 2.9.3