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rxrpc: Fix missing notification

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Under some circumstances, rxrpc will fail a transmit a packet through the
underlying UDP socket (ie. UDP sendmsg returns an error).  This may result
in a call getting stuck.

In the instance being seen, where AFS tries to send a probe to the Volume
Location server, tracepoints show the UDP Tx failure (in this case returing
error 99 EADDRNOTAVAIL) and then nothing more:

 afs_make_vl_call: c=0000015d VL.GetCapabilities
 rxrpc_call: c=0000015d NWc u=1 sp=rxrpc_kernel_begin_call+0x106/0x170 [rxrpc] a=00000000dd89ee8a
 rxrpc_call: c=0000015d Gus u=2 sp=rxrpc_new_client_call+0x14f/0x580 [rxrpc] a=00000000e20e4b08
 rxrpc_call: c=0000015d SEE u=2 sp=rxrpc_activate_one_channel+0x7b/0x1c0 [rxrpc] a=00000000e20e4b08
 rxrpc_call: c=0000015d CON u=2 sp=rxrpc_kernel_begin_call+0x106/0x170 [rxrpc] a=00000000e20e4b08
 rxrpc_tx_fail: c=0000015d r=1 ret=-99 CallDataNofrag

The problem is that if the initial packet fails and the retransmission
timer hasn't been started, the call is set to completed and an error is
returned from rxrpc_send_data_packet() to rxrpc_queue_packet().  Though
rxrpc_instant_resend() is called, this does nothing because the call is
marked completed.

So rxrpc_notify_socket() isn't called and the error is passed back up to
rxrpc_send_data(), rxrpc_kernel_send_data() and thence to afs_make_call()
and afs_vl_get_capabilities() where it is simply ignored because it is
assumed that the result of a probe will be collected asynchronously.

Fileserver probing is similarly affected via afs_fs_get_capabilities().

Fix this by always issuing a notification in __rxrpc_set_call_completion()
if it shifts a call to the completed state, even if an error is also
returned to the caller through the function return value.

Also put in a little bit of optimisation to avoid taking the call
state_lock and disabling softirqs if the call is already in the completed
state and remove some now redundant rxrpc_notify_socket() calls.

Fixes: f5c17aaeb2 ("rxrpc: Calls should only have one terminal state")
Reported-by: Gerry Seidman <gerry@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
This commit is contained in:
David Howells
2020-06-03 22:21:16 +01:00
parent 3067bf8c59
commit 5ac0d62226
6 changed files with 21 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files
net/rxrpc/recvmsg.c
+13 -8
View File
@@ -73,6 +73,7 @@ bool __rxrpc_set_call_completion(struct rxrpc_call *call,
call->state = RXRPC_CALL_COMPLETE;
trace_rxrpc_call_complete(call);
wake_up(&call->waitq);
rxrpc_notify_socket(call);
return true;
}
return false;
@@ -83,11 +84,13 @@ bool rxrpc_set_call_completion(struct rxrpc_call *call,
u32 abort_code,
int error)
{
bool ret;
bool ret = false;
write_lock_bh(&call->state_lock);
ret = __rxrpc_set_call_completion(call, compl, abort_code, error);
write_unlock_bh(&call->state_lock);
if (call->state < RXRPC_CALL_COMPLETE) {
write_lock_bh(&call->state_lock);
ret = __rxrpc_set_call_completion(call, compl, abort_code, error);
write_unlock_bh(&call->state_lock);
}
return ret;
}
@@ -101,11 +104,13 @@ bool __rxrpc_call_completed(struct rxrpc_call *call)
bool rxrpc_call_completed(struct rxrpc_call *call)
{
bool ret;
bool ret = false;
write_lock_bh(&call->state_lock);
ret = __rxrpc_call_completed(call);
write_unlock_bh(&call->state_lock);
if (call->state < RXRPC_CALL_COMPLETE) {
write_lock_bh(&call->state_lock);
ret = __rxrpc_call_completed(call);
write_unlock_bh(&call->state_lock);
}
return ret;
}