ceph: don't reference req after put

(cherry picked from commit 7d5f24812bd182a2471cb69c1c2baf0648332e1f)

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index fc4e60e73552135ea0bf462f32fae4ac39ec4229..183baf40383a21e0a8a0a4b5d2a1a6f459990956 100644 (file)
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -873,9 +873,9 @@ 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);