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authorDavid Howells <dhowells@redhat.com>2018-11-13 01:33:22 +0300
committerDavid S. Miller <davem@davemloft.net>2018-11-15 22:35:40 +0300
commit7150ceaacb27f7b3bf494e72cd4be4e11612dfff (patch)
treecdb1fb191dc649c0f1563045fe17ef0630690b2c /Documentation
parentebcd210e93b2a984b7a7b82d45f7f0d21b7ec2d2 (diff)
downloadlinux-7150ceaacb27f7b3bf494e72cd4be4e11612dfff.tar.xz
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>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/networking/rxrpc.txt17
1 files changed, 11 insertions, 6 deletions
diff --git a/Documentation/networking/rxrpc.txt b/Documentation/networking/rxrpc.txt
index 605e00cdd6be..89f1302d593a 100644
--- a/Documentation/networking/rxrpc.txt
+++ b/Documentation/networking/rxrpc.txt
@@ -1056,18 +1056,23 @@ The kernel interface functions are as follows:
u32 rxrpc_kernel_check_life(struct socket *sock,
struct rxrpc_call *call);
+ void rxrpc_kernel_probe_life(struct socket *sock,
+ struct rxrpc_call *call);
- This returns a number that is updated when ACKs are received from the peer
- (notably including PING RESPONSE ACKs which we can elicit by sending PING
- ACKs to see if the call still exists on the server). The caller should
- compare the numbers of two calls to see if the call is still alive after
- waiting for a suitable interval.
+ The first function returns a number that is updated when ACKs are received
+ from the peer (notably including PING RESPONSE ACKs which we can elicit by
+ sending PING ACKs to see if the call still exists on the server). The
+ caller should compare the numbers of two calls to see if the call is still
+ alive after waiting for a suitable interval.
This allows the caller to work out if the server is still contactable and
if the call is still alive on the server whilst waiting for the server to
process a client operation.
- This function may transmit a PING ACK.
+ The second function causes a ping ACK to be transmitted to try to provoke
+ the peer into responding, which would then cause the value returned by the
+ first function to change. Note that this must be called in TASK_RUNNING
+ state.
(*) Get reply timestamp.