From a72cbf83b0cb2368568d4e78cf1687079aad4d25 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Tue, 8 Aug 2017 22:56:52 -0700 Subject: [PATCH] md/r5cache: call mddev_lock/unlock() in r5c_journal_mode_show 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 Signed-off-by: Shaohua Li --- drivers/md/raid5-cache.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c index 2dcbafa8e66c..e357ed367140 100644 --- a/drivers/md/raid5-cache.c +++ b/drivers/md/raid5-cache.c @@ -2529,11 +2529,18 @@ 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; - if (!conf->log) + ret = mddev_lock(mddev); + if (ret) + return ret; + + 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 +2558,7 @@ static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page) default: ret = 0; } + mddev_unlock(mddev); return ret; } -- 2.20.1