Looks good,
Reviewed-By: Devesh Sharma <devesh.sharma@xxxxxxxxxxxxx>
Will send a test-report of this series with ocrdma drivers.
On Tue, Oct 6, 2015 at 8:28 PM, Chuck Lever <chuck.lever@xxxxxxxxxx> wrote:
> 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 7f23f6f6e388 ("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: 7f23f6f6e388 ("xprtrmda: Reduce lock contention in ...")
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
> net/sunrpc/xprtrdma/verbs.c | 66 +++++++------------------------------------
> 1 file changed, 10 insertions(+), 56 deletions(-)
>
> diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
> index 8a477e2..c713909 100644
> --- a/net/sunrpc/xprtrdma/verbs.c
> +++ b/net/sunrpc/xprtrdma/verbs.c
> @@ -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
>
> --
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