From: Daniel Wagner dwagner@suse.de
[ Upstream commit 9edceaf43050f5ba1dd7d0011bcf68a736a17743 ]
When we remove the siblings entry, we update ns->head->list, hence we can't separate the removal and test for being empty. They have to be in the same critical section to avoid a race.
To avoid breaking the refcounting imbalance again, add a list empty check to nvme_find_ns_head.
Fixes: 5396fdac56d8 ("nvme: fix refcounting imbalance when all paths are down") Signed-off-by: Daniel Wagner dwagner@suse.de Reviewed-by: Hannes Reinecke hare@suse.de Tested-by: Hannes Reinecke hare@suse.de Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/nvme/host/core.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 2f0cbaba12ac..84e7cb9f1968 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -3496,7 +3496,9 @@ static struct nvme_ns_head *nvme_find_ns_head(struct nvme_subsystem *subsys, lockdep_assert_held(&subsys->lock);
list_for_each_entry(h, &subsys->nsheads, entry) { - if (h->ns_id == nsid && nvme_tryget_ns_head(h)) + if (h->ns_id != nsid) + continue; + if (!list_empty(&h->list) && nvme_tryget_ns_head(h)) return h; }
@@ -3821,6 +3823,10 @@ static void nvme_ns_remove(struct nvme_ns *ns)
mutex_lock(&ns->ctrl->subsys->lock); list_del_rcu(&ns->siblings); + if (list_empty(&ns->head->list)) { + list_del_init(&ns->head->entry); + last_path = true; + } mutex_unlock(&ns->ctrl->subsys->lock);
synchronize_rcu(); /* guarantee not available in head->list */ @@ -3840,13 +3846,6 @@ static void nvme_ns_remove(struct nvme_ns *ns) list_del_init(&ns->list); up_write(&ns->ctrl->namespaces_rwsem);
- /* Synchronize with nvme_init_ns_head() */ - mutex_lock(&ns->head->subsys->lock); - if (list_empty(&ns->head->list)) { - list_del_init(&ns->head->entry); - last_path = true; - } - mutex_unlock(&ns->head->subsys->lock); if (last_path) nvme_mpath_shutdown_disk(ns->head); nvme_put_ns(ns);