ceph: don't reference req after put

In __unregister_request(), there is a call to list_del_init()
referencing a request that was the subject of a call to
ceph_osdc_put_request() on the previous line.  This is not
safe, because the request structure could have been freed
by the time we reach the list_del_init().

Fix this by reversing the order of these lines.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-off-by: Sage Weil <sage@inktank.com>

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 7ebfe13267e69dacac8721738e93ef0eb657081a..ac7be7202faa73fd754d762b122642162b496995 100644 (file)
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -871,9 +871,9 @@ static void __unregister_request(struct ceph_osd_client *osdc,
                        req->r_osd = NULL;
        }
 
+       list_del_init(&req->r_req_lru_item);
        ceph_osdc_put_request(req);
 
-       list_del_init(&req->r_req_lru_item);
        if (osdc->num_requests == 0) {
                dout(" no requests, canceling timeout\n");
                __cancel_osd_timeout(osdc);