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Subject[PATCH v4 05/11] md/raid5-cache: Take mddev_lock in r5c_journal_mode_show()
The mddev->lock spinlock doesn't protect against the removal of
conf->log in r5l_exit_log() so conf->log may be freed before it
is used.

To fix this, take the mddev_lock() insteaad of the mddev->lock spinlock.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
drivers/md/raid5-cache.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 83c184eddbda..ca8fc317da95 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -2534,12 +2534,13 @@ static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page)
struct r5conf *conf;
int ret;

- spin_lock(&mddev->lock);
+ ret = mddev_lock(mddev);
+ if (ret)
+ return ret;
+
conf = mddev->private;
- if (!conf || !conf->log) {
- spin_unlock(&mddev->lock);
- return 0;
- }
+ if (!conf || !conf->log)
+ goto out_unlock;

switch (conf->log->r5c_journal_mode) {
case R5C_JOURNAL_MODE_WRITE_THROUGH:
@@ -2557,7 +2558,9 @@ static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page)
default:
ret = 0;
}
- spin_unlock(&mddev->lock);
+
+out_unlock:
+ mddev_unlock(mddev);
return ret;
}

--
2.30.2
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