rx: Don't clear the receive queue when out of packets

We can end up discarding a receive queue that's been soft acked,
effectively taking back soft acks we sent. Whilst the RX
documentation says that a client can drop soft acked packets at
will, our RX implementation assumes that if the final packet in
a call has been soft acked, we won't clear the queue. If a client
clears the queue in this situation, the call will hang.

What *should* happen is that we should take necessary locks,
confirm that we have not soft-acked all of the packets in a flow,
and then discard, or, if we're just going to discard, error the
call.

Reviewed-on: http://gerrit.openafs.org/5603
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>
(cherry-picked from f722a75fe21963d64217375f1f7bbb0eb14befb4)

Change-Id: Ie2f14a0ed7b6d258a7f456387df44ac95fd1748c
Reviewed-on: http://gerrit.openafs.org/5820
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>

diff --git a/src/rx/rx.c b/src/rx/rx.c
index bb42e75fcd3e73b0e74b77f675fb4236a68300eb..4245b18494e07ccff0d3b3bb520190e04929938b 100644 (file)
--- a/src/rx/rx.c
+++ b/src/rx/rx.c
@@ -3853,8 +3853,9 @@ rxi_ReceiveDataPacket(struct rx_call *call,
        call->rprev = np->header.serial;
        rxi_calltrace(RX_TRACE_DROP, call);
        dpf(("packet %"AFS_PTR_FMT" dropped on receipt - quota problems", np));
-       if (rxi_doreclaim)
-           rxi_ClearReceiveQueue(call);
+        /* We used to clear the receive queue here, in an attempt to free
+         * packets. However this is unsafe if the queue has received a
+         * soft ACK for the final packet */
        clock_GetTime(&now);
        when = now;
        clock_Add(&when, &rx_softAckDelay);

diff --git a/src/rx/rx_globals.h b/src/rx/rx_globals.h
index c4c82996477aab95d8b89d0b44d07faf74ff6306..7723d61a89ba4912c6d39082222e15d246341769 100644 (file)
--- a/src/rx/rx_globals.h
+++ b/src/rx/rx_globals.h
@@ -483,7 +483,6 @@ EXT osi_socket rx_minSocketNumber GLOBALSINIT(0x7fffffff);
 #define        RX_MAX_QUOTA    15      /* part of min packet computation */
 EXT int rx_packetQuota[RX_N_PACKET_CLASSES] GLOBALSINIT(RX_PACKET_QUOTAS);
 EXT int meltdown_1pkt GLOBALSINIT(1);  /* prefer to schedule single-packet calls */
-EXT int rxi_doreclaim GLOBALSINIT(1);  /* if discard one packet, discard all */
 EXT int rxi_md2cnt GLOBALSINIT(0);     /* counter of skipped calls */
 EXT int rxi_2dchoice GLOBALSINIT(1);   /* keep track of another call to schedule */