Hi, Looks good...
Acked-by: Steven Whitehouse <swhit...@redhat.com> Steve. On 13/11/15 12:16, Andrew Price wrote:
This lockdep splat was being triggered on umount: [55715.973122] =============================== [55715.980169] [ INFO: suspicious RCU usage. ] [55715.981021] 4.3.0-11553-g8d3de01-dirty #15 Tainted: G W [55715.982353] ------------------------------- [55715.983301] fs/gfs2/glock.c:1427 suspicious rcu_dereference_protected() usage! The code it refers to is the rht_for_each_entry_safe usage in glock_hash_walk. The condition that triggers the warning is lockdep_rht_bucket_is_held(tbl, hash) which is checked in the __rcu_dereference_protected macro. The rhashtable buckets are not changed in glock_hash_walk so it's safe to rely on the rcu protection. Replace the rht_for_each_entry_safe() usage with rht_for_each_entry_rcu(), which doesn't care whether the bucket lock is held if the rcu read lock is held. Signed-off-by: Andrew Price <anpr...@redhat.com> --- fs/gfs2/glock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 32e7471..430326e 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1417,14 +1417,14 @@ static struct shrinker glock_shrinker = { static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp) { struct gfs2_glock *gl; - struct rhash_head *pos, *next; + struct rhash_head *pos; const struct bucket_table *tbl; int i;rcu_read_lock();tbl = rht_dereference_rcu(gl_hash_table.tbl, &gl_hash_table); for (i = 0; i < tbl->size; i++) { - rht_for_each_entry_safe(gl, pos, next, tbl, i, gl_node) { + rht_for_each_entry_rcu(gl, pos, tbl, i, gl_node) { if ((gl->gl_name.ln_sbd == sdp) && lockref_get_not_dead(&gl->gl_lockref)) examiner(gl);
