SUNRPC: Don't hold the transport lock across socket copy operations

Instead add a mechanism to ensure that the request doesn't disappear
from underneath us while copying from the socket. We do this by
preventing xprt_release() from freeing the XDR buffers until the
flag RPC_TASK_MSG_RECV has been cleared from the request.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>

1 files changed, 18 insertions, 5 deletions

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 4f154d388748..04dbc7027712 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -973,6 +973,8 @@ static void xs_local_data_read_skb(struct rpc_xprt *xprt,
         rovr = xprt_lookup_rqst(xprt, *xp);
         if (!rovr)
                 goto out_unlock;
+        xprt_pin_rqst(rovr);
+        spin_unlock_bh(&xprt->transport_lock);
         task = rovr->rq_task;
 
         copied = rovr->rq_private_buf.buflen;
@@ -981,11 +983,14 @@ static void xs_local_data_read_skb(struct rpc_xprt *xprt,
 
         if (xs_local_copy_to_xdr(&rovr->rq_private_buf, skb)) {
                 dprintk("RPC:       sk_buff copy failed\n");
-                goto out_unlock;
+                spin_lock_bh(&xprt->transport_lock);
+                goto out_unpin;
         }
 
+        spin_lock_bh(&xprt->transport_lock);
         xprt_complete_rqst(task, copied);
-
+out_unpin:
+        xprt_unpin_rqst(rovr);
  out_unlock:
         spin_unlock_bh(&xprt->transport_lock);
 }
@@ -1054,6 +1059,8 @@ static void xs_udp_data_read_skb(struct rpc_xprt *xprt,
         rovr = xprt_lookup_rqst(xprt, *xp);
         if (!rovr)
                 goto out_unlock;
+        xprt_pin_rqst(rovr);
+        spin_unlock_bh(&xprt->transport_lock);
         task = rovr->rq_task;
 
         if ((copied = rovr->rq_private_buf.buflen) > repsize)
@@ -1062,14 +1069,17 @@ static void xs_udp_data_read_skb(struct rpc_xprt *xprt,
         /* Suck it into the iovec, verify checksum if not done by hw. */
         if (csum_partial_copy_to_xdr(&rovr->rq_private_buf, skb)) {
                 __UDPX_INC_STATS(sk, UDP_MIB_INERRORS);
-                goto out_unlock;
+                spin_lock_bh(&xprt->transport_lock);
+                goto out_unpin;
         }
 
         __UDPX_INC_STATS(sk, UDP_MIB_INDATAGRAMS);
 
+        spin_lock_bh(&xprt->transport_lock);
         xprt_adjust_cwnd(xprt, task, copied);
         xprt_complete_rqst(task, copied);
-
+out_unpin:
+        xprt_unpin_rqst(rovr);
  out_unlock:
         spin_unlock_bh(&xprt->transport_lock);
 }
@@ -1351,12 +1361,15 @@ static inline int xs_tcp_read_reply(struct rpc_xprt *xprt,
                 spin_unlock_bh(&xprt->transport_lock);
                 return -1;
         }
+        xprt_pin_rqst(req);
+        spin_unlock_bh(&xprt->transport_lock);
 
         xs_tcp_read_common(xprt, desc, req);
 
+        spin_lock_bh(&xprt->transport_lock);
         if (!(transport->tcp_flags & TCP_RCV_COPY_DATA))
                 xprt_complete_rqst(req->rq_task, transport->tcp_copied);
-
+        xprt_unpin_rqst(req);
         spin_unlock_bh(&xprt->transport_lock);
         return 0;
 }