From: Christoph Hellwig <hch@lst.de>
Date: Wed, 18 Oct 2017 13:20:01 +0200
Subject: nvme: use kref_get_unless_zero in nvme_find_get_ns
Patch-mainline: v4.15-rc1
Git-commit: 2dd4122854f697afc777582d18548dded03ce5dd
References: FATE#323952, FATE#322506
For kref_get_unless_zero to protect against lookup vs free races we need
to use it in all places where we aren't guaranteed to already hold a
reference. There is no such guarantee in nvme_find_get_ns, so switch to
kref_get_unless_zero in this function.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
---
drivers/nvme/host/core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2299,7 +2299,8 @@ static struct nvme_ns *nvme_find_get_ns(
mutex_lock(&ctrl->namespaces_mutex);
list_for_each_entry(ns, &ctrl->namespaces, list) {
if (ns->ns_id == nsid) {
- kref_get(&ns->kref);
+ if (!kref_get_unless_zero(&ns->kref))
+ continue;
ret = ns;
break;
}