blk-mq: Fix tagset reinit in the presence of cpu hot-unplug

[ Upstream commit 0067d4b020ea07a58540acb2c5fcd3364bf326e0 ]

In case cpu was unplugged, we need to make sure not to assume
that the tags for that cpu are still allocated. so check
for null tags when reinitializing a tagset.

Reported-by: Yi Zhang <yizhan@redhat.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index dcf5ce3..4bc701b 100644 (file)
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -311,6 +311,9 @@ int blk_mq_reinit_tagset(struct blk_mq_tag_set *set)
        for (i = 0; i < set->nr_hw_queues; i++) {
                struct blk_mq_tags *tags = set->tags[i];
 
+               if (!tags)
+                       continue;
+
                for (j = 0; j < tags->nr_tags; j++) {
                        if (!tags->rqs[j])
                                continue;