nvme_round_robin_path() should test if the return ns pointer is
valid. nvme_next_ns() will return a NULL pointer if there is no path
left.

Fixes: 75c10e732724 ("nvme-multipath: round-robin I/O policy")
Cc: Hannes Reinecke <hare@suse.de>
Signed-off-by: Daniel Wagner <redacted>
---
v2:
   - moved NULL test into the if conditional statement
   - added Fixes tag

  drivers/nvme/host/multipath.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 9ac762b28811..282b7a4ea9a9 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c

@@ -221,7 +221,7 @@ static struct nvme_ns *nvme_round_robin_path(struct nvme_ns_head *head,
  	}
  
  	for (ns = nvme_next_ns(head, old);
-	     ns != old;
+	     ns && ns != old;
  	     ns = nvme_next_ns(head, ns)) {
  		if (nvme_path_is_disabled(ns))
  			continue;