rxrpc: Fix life check

The life-checking function, which is used by kAFS to make sure that a call
is still live in the event of a pending signal, only samples the received
packet serial number counter; it doesn't actually provoke a change in the
counter, rather relying on the server to happen to give us a packet in the
time window.

Fix this by adding a function to force a ping to be transmitted.

kAFS then keeps track of whether there's been a stall, and if so, uses the
new function to ping the server, resetting the timeout to allow the reply
to come back.

If there's a stall, a ping and the call is *still* stalled in the same
place after another period, then the call will be aborted.

Fixes: bc5e3a546d55 ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Fixes: f4d15fb6f99a ("rxrpc: Provide functions for allowing cleaner handling of signals")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 1 deletions

diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 59970886690f..a7b44863d502 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -576,6 +576,7 @@ static long afs_wait_for_call_to_complete(struct afs_call *call,
 {
 	signed long rtt2, timeout;
 	long ret;
+	bool stalled = false;
 	u64 rtt;
 	u32 life, last_life;
 
@@ -609,12 +610,20 @@ static long afs_wait_for_call_to_complete(struct afs_call *call,
 
 		life = rxrpc_kernel_check_life(call->net->socket, call->rxcall);
 		if (timeout == 0 &&
-		    life == last_life && signal_pending(current))
+		    life == last_life && signal_pending(current)) {
+			if (stalled)
 				break;
+			__set_current_state(TASK_RUNNING);
+			rxrpc_kernel_probe_life(call->net->socket, call->rxcall);
+			timeout = rtt2;
+			stalled = true;
+			continue;
+		}
 
 		if (life != last_life) {
 			timeout = rtt2;
 			last_life = life;
+			stalled = false;
 		}
 
 		timeout = schedule_timeout(timeout);