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authorYu Kuai <yukuai3@huawei.com>2023-11-24 10:59:53 +0300
committerMike Snitzer <snitzer@kernel.org>2023-12-18 21:05:21 +0300
commitdb29d79b34d9593179de5f868be45c650923e7b4 (patch)
tree0594db7328418a993dd1a9aff8120cda9ade4887 /drivers/md
parentceb6a6f023fd3e8b07761ed900352ef574010bcb (diff)
downloadlinux-db29d79b34d9593179de5f868be45c650923e7b4.tar.xz
dm-raid: delay flushing event_work() after reconfig_mutex is released
After commit db5e653d7c9f ("md: delay choosing sync action to md_start_sync()"), md_start_sync() will hold 'reconfig_mutex', however, in order to make sure event_work is done, __md_stop() will flush workqueue with reconfig_mutex grabbed, hence if sync_work is still pending, deadlock will be triggered. Fortunately, former pacthes to fix stopping sync_thread already make sure all sync_work is done already, hence such deadlock is not possible anymore. However, in order not to cause confusions for people by this implicit dependency, delay flushing event_work to dm-raid where 'reconfig_mutex' is not held, and add some comments to emphasize that the workqueue can't be flushed with 'reconfig_mutex'. Fixes: db5e653d7c9f ("md: delay choosing sync action to md_start_sync()") Depends-on: f52f5c71f3d4 ("md: fix stopping sync thread") Signed-off-by: Yu Kuai <yukuai3@huawei.com> Acked-by: Xiao Ni <xni@redhat.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm-raid.c3
-rw-r--r--drivers/md/md.c11
2 files changed, 11 insertions, 3 deletions
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 91ebdcc6e9a8..eb009d6bb03a 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -3317,6 +3317,9 @@ static void raid_dtr(struct dm_target *ti)
mddev_lock_nointr(&rs->md);
md_stop(&rs->md);
mddev_unlock(&rs->md);
+
+ if (work_pending(&rs->md.event_work))
+ flush_work(&rs->md.event_work);
raid_set_free(rs);
}
diff --git a/drivers/md/md.c b/drivers/md/md.c
index b066abbffd10..9bdd57324c37 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -82,6 +82,14 @@ static struct module *md_cluster_mod;
static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
static struct workqueue_struct *md_wq;
+
+/*
+ * This workqueue is used for sync_work to register new sync_thread, and for
+ * del_work to remove rdev, and for event_work that is only set by dm-raid.
+ *
+ * Noted that sync_work will grab reconfig_mutex, hence never flush this
+ * workqueue whith reconfig_mutex grabbed.
+ */
static struct workqueue_struct *md_misc_wq;
struct workqueue_struct *md_bitmap_wq;
@@ -6330,9 +6338,6 @@ static void __md_stop(struct mddev *mddev)
struct md_personality *pers = mddev->pers;
md_bitmap_destroy(mddev);
mddev_detach(mddev);
- /* Ensure ->event_work is done */
- if (mddev->event_work.func)
- flush_workqueue(md_misc_wq);
spin_lock(&mddev->lock);
mddev->pers = NULL;
spin_unlock(&mddev->lock);