From a12f5d48bdfeb5fe10157ac01c3de29269f457c6 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 23 Nov 2014 09:34:29 -0800 Subject: dm: use rcu_dereference_protected instead of rcu_dereference rcu_dereference() should be used in sections protected by rcu_read_lock. For writers, holding some kind of mutex or lock, rcu_dereference_protected() is the way to go, adding explicit lockdep bits. In __unbind(), we are the last user of this mapped device, so can use the constant '1' instead of a lockdep_is_held(), not consistent with other uses of rcu_dereference_protected() which use md->suspend_lock mutex. Reported-by: Kirill A. Shutemov Signed-off-by: Eric Dumazet Fixes: 33423974bfc1 ("dm: Use rcu_dereference() for accessing rcu pointer") Cc: Pranith Kumar [snitzer: allow lines longer than 80 columns, refine subject] Signed-off-by: Mike Snitzer --- drivers/md/dm.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'drivers/md/dm.c') diff --git a/drivers/md/dm.c b/drivers/md/dm.c index a0ece87ad426..8f37ed215b19 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2335,7 +2335,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t, merge_is_optional = dm_table_merge_is_optional(t); - old_map = rcu_dereference(md->map); + old_map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock)); rcu_assign_pointer(md->map, t); md->immutable_target_type = dm_table_get_immutable_target_type(t); @@ -2355,7 +2355,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t, */ static struct dm_table *__unbind(struct mapped_device *md) { - struct dm_table *map = rcu_dereference(md->map); + struct dm_table *map = rcu_dereference_protected(md->map, 1); if (!map) return NULL; @@ -2850,7 +2850,7 @@ retry: goto retry; } - map = rcu_dereference(md->map); + map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock)); r = __dm_suspend(md, map, suspend_flags, TASK_INTERRUPTIBLE); if (r) @@ -2908,7 +2908,7 @@ retry: goto retry; } - map = rcu_dereference(md->map); + map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock)); if (!map || !dm_table_get_size(map)) goto out; @@ -2943,7 +2943,7 @@ static void __dm_internal_suspend(struct mapped_device *md, unsigned suspend_fla return; /* nest suspend */ } - map = rcu_dereference(md->map); + map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock)); /* * Using TASK_UNINTERRUPTIBLE because only NOFLUSH internal suspend is -- cgit v1.2.3