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| author | Andrew Price <anprice@redhat.com> | 2015-11-12 14:07:52 -0600 |
|---|---|---|
| committer | Bob Peterson <rpeterso@redhat.com> | 2015-11-16 11:57:59 -0600 |
| commit | 3dd1dd8c696bdb7c8dcc9456cb23558ad1b336b8 (patch) | |
| tree | 3ec8d2b7d442737c15f6b83999713c1c38cbdfc7 /fs/gfs2 | |
| parent | 6fde22426be6af261816db5941744b8d3c4c7f96 (diff) | |
| download | blackbird-obmc-linux-3dd1dd8c696bdb7c8dcc9456cb23558ad1b336b8.tar.gz blackbird-obmc-linux-3dd1dd8c696bdb7c8dcc9456cb23558ad1b336b8.zip | |
GFS2: Use rht_for_each_entry_rcu in glock_hash_walk
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 <anprice@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/gfs2')
| -rw-r--r-- | fs/gfs2/glock.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 32e74710b1aa..430326e631dc 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); |
