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rxrpc: Fix life check

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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: bc5e3a546d ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Fixes: f4d15fb6f9 ("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>
This commit is contained in:
David Howells
2018-11-12 22:33:22 +00:00
committed by David S. Miller
parent ebcd210e93
commit 7150ceaacb
5 changed files with 48 additions and 12 deletions
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27
net/rxrpc/af_rxrpc.c
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@@ -375,16 +375,35 @@ EXPORT_SYMBOL(rxrpc_kernel_end_call);
* getting ACKs from the server. Returns a number representing the life state
* which can be compared to that returned by a previous call.
*
* If this is a client call, ping ACKs will be sent to the server to find out
* whether it's still responsive and whether the call is still alive on the
* server.
* If the life state stalls, rxrpc_kernel_probe_life() should be called and
* then 2RTT waited.
*/
u32 rxrpc_kernel_check_life(struct socket *sock, struct rxrpc_call *call)
u32 rxrpc_kernel_check_life(const struct socket *sock,
const struct rxrpc_call *call)
{
return call->acks_latest;
}
EXPORT_SYMBOL(rxrpc_kernel_check_life);
/**
* rxrpc_kernel_probe_life - Poke the peer to see if it's still alive
* @sock: The socket the call is on
* @call: The call to check
*
* In conjunction with rxrpc_kernel_check_life(), allow a kernel service to
* find out whether a call is still alive by pinging it. This should cause the
* life state to be bumped in about 2*RTT.
*
* The must be called in TASK_RUNNING state on pain of might_sleep() objecting.
*/
void rxrpc_kernel_probe_life(struct socket *sock, struct rxrpc_call *call)
{
rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,
rxrpc_propose_ack_ping_for_check_life);
rxrpc_send_ack_packet(call, true, NULL);
}
EXPORT_SYMBOL(rxrpc_kernel_probe_life);
/**
* rxrpc_kernel_get_epoch - Retrieve the epoch value from a call.
* @sock: The socket the call is on