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xprtrdma: Re-arm after missed events

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ib_req_notify_cq(IB_CQ_REPORT_MISSED_EVENTS) returns a positive
value if WCs were added to a CQ after the last completion upcall
but before the CQ has been re-armed.

Commit 7f23f6f6e3 ("xprtrmda: Reduce lock contention in
completion handlers") assumed that when ib_req_notify_cq() returned
a positive RC, the CQ had also been successfully re-armed, making
it safe to return control to the provider without losing any
completion signals. That is an invalid assumption.

Change both completion handlers to continue polling while
ib_req_notify_cq() returns a positive value.

Fixes: 7f23f6f6e3 ("xprtrmda: Reduce lock contention in ...")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Devesh Sharma <devesh.sharma@avagotech.com>
Tested-By: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2015-10-24 17:26:37 -04:00 committed by Anna Schumaker
parent a045178887
commit 7b3d770c67
1 changed files with 10 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

66
net/sunrpc/xprtrdma/verbs.c
View File

@ -179,38 +179,17 @@ rpcrdma_sendcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
return 0;
}
/*
* Handle send, fast_reg_mr, and local_inv completions.
*
* Send events are typically suppressed and thus do not result
* in an upcall. Occasionally one is signaled, however. This
* prevents the provider's completion queue from wrapping and
* losing a completion.
/* Handle provider send completion upcalls.
*/
static void
rpcrdma_sendcq_upcall(struct ib_cq *cq, void *cq_context)
{
struct rpcrdma_ep *ep = (struct rpcrdma_ep *)cq_context;
int rc;
rc = rpcrdma_sendcq_poll(cq, ep);
if (rc) {
dprintk("RPC: %s: ib_poll_cq failed: %i\n",
__func__, rc);
return;
}
rc = ib_req_notify_cq(cq,
IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
if (rc == 0)
return;
if (rc < 0) {
dprintk("RPC: %s: ib_req_notify_cq failed: %i\n",
__func__, rc);
return;
}
rpcrdma_sendcq_poll(cq, ep);
do {
rpcrdma_sendcq_poll(cq, ep);
} while (ib_req_notify_cq(cq, IB_CQ_NEXT_COMP |
IB_CQ_REPORT_MISSED_EVENTS) > 0);
}
static void
@ -274,42 +253,17 @@ out_schedule:
return rc;
}
/*
* Handle receive completions.
*
* It is reentrant but processes single events in order to maintain
* ordering of receives to keep server credits.
*
* It is the responsibility of the scheduled tasklet to return
* recv buffers to the pool. NOTE: this affects synchronization of
* connection shutdown. That is, the structures required for
* the completion of the reply handler must remain intact until
* all memory has been reclaimed.
/* Handle provider receive completion upcalls.
*/
static void
rpcrdma_recvcq_upcall(struct ib_cq *cq, void *cq_context)
{
struct rpcrdma_ep *ep = (struct rpcrdma_ep *)cq_context;
int rc;
rc = rpcrdma_recvcq_poll(cq, ep);
if (rc) {
dprintk("RPC: %s: ib_poll_cq failed: %i\n",
__func__, rc);
return;
}
rc = ib_req_notify_cq(cq,
IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
if (rc == 0)
return;
if (rc < 0) {
dprintk("RPC: %s: ib_req_notify_cq failed: %i\n",
__func__, rc);
return;
}
rpcrdma_recvcq_poll(cq, ep);
do {
rpcrdma_recvcq_poll(cq, ep);
} while (ib_req_notify_cq(cq, IB_CQ_NEXT_COMP |
IB_CQ_REPORT_MISSED_EVENTS) > 0);
}
static void