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 <songliubraving@xxxxxx>
Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx>
---
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
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