9p/xen: Fix end of loop tests for list_for_each_entry

This patch addresses the following problems:
 - priv can never be NULL, so this part of the check is useless
 - if the loop ran through the whole list, priv->client is invalid and
it is more appropriate and sufficient to check for the end of
list_for_each_entry loop condition.

Link: http://lkml.kernel.org/r/20210727000709.225032-1-harshvardhan.jha@oracle.com
Signed-off-by: Harshvardhan Jha <harshvardhan.jha@oracle.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Tested-by: Stefano Stabellini <sstabellini@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>

diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index f4fea28e05da68f005c179c564441da59068d4cb..3ec1a51a6944ea0d322b7c0b3cccb8b8cc616f05 100644 (file)
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -138,7 +138,7 @@ static bool p9_xen_write_todo(struct xen_9pfs_dataring *ring, RING_IDX size)
 
 static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
 {
-       struct xen_9pfs_front_priv *priv = NULL;
+       struct xen_9pfs_front_priv *priv;
        RING_IDX cons, prod, masked_cons, masked_prod;
        unsigned long flags;
        u32 size = p9_req->tc.size;
@@ -151,7 +151,7 @@ static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
                        break;
        }
        read_unlock(&xen_9pfs_lock);
-       if (!priv || priv->client != client)
+       if (list_entry_is_head(priv, &xen_9pfs_devs, list))
                return -EINVAL;
 
        num = p9_req->tc.tag % priv->num_rings;