From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dennis Dalessandro Subject: [PATCH for-rc 2/3] IB/hfi1: Close PSM sdma_progress sleep window Date: Fri, 07 Jun 2019 08:25:31 -0400 Message-ID: <20190607122531.158478.35392.stgit@awfm-01.aw.intel.com> References: <20190607113807.157915.48581.stgit@awfm-01.aw.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190607113807.157915.48581.stgit@awfm-01.aw.intel.com> Sender: stable-owner@vger.kernel.org To: jgg@ziepe.ca, dledford@redhat.com Cc: linux-rdma@vger.kernel.org, Mike Marciniszyn , stable@vger.kernel.org, Gary Leshner List-Id: linux-rdma@vger.kernel.org From: Mike Marciniszyn The call to sdma_progress() is called outside the wait lock. In this case, there is a race condition where sdma_progress() can return false and the sdma_engine can idle. If that happens, there will be no more sdma interrupts to cause the wakeup and the user_sdma xmit will hang. Fix by moving the lock to enclose the sdma_progress() call. Also, delete busycount. The need for this was removed by: commit bcad29137a97 ("IB/hfi1: Serve the most starved iowait entry first") Cc: Fixes: 7724105686e7 ("IB/hfi1: add driver files") Reviewed-by: Gary Leshner Signed-off-by: Mike Marciniszyn Signed-off-by: Dennis Dalessandro --- drivers/infiniband/hw/hfi1/user_sdma.c | 12 ++++-------- drivers/infiniband/hw/hfi1/user_sdma.h | 1 - 2 files changed, 4 insertions(+), 9 deletions(-) diff --git a/drivers/infiniband/hw/hfi1/user_sdma.c b/drivers/infiniband/hw/hfi1/user_sdma.c index 8bfbc6d..fd754a1 100644 --- a/drivers/infiniband/hw/hfi1/user_sdma.c +++ b/drivers/infiniband/hw/hfi1/user_sdma.c @@ -130,20 +130,16 @@ static int defer_packet_queue( { struct hfi1_user_sdma_pkt_q *pq = container_of(wait->iow, struct hfi1_user_sdma_pkt_q, busy); - struct user_sdma_txreq *tx = - container_of(txreq, struct user_sdma_txreq, txreq); - if (sdma_progress(sde, seq, txreq)) { - if (tx->busycount++ < MAX_DEFER_RETRY_COUNT) - goto eagain; - } + write_seqlock(&sde->waitlock); + if (sdma_progress(sde, seq, txreq)) + goto eagain; /* * We are assuming that if the list is enqueued somewhere, it * is to the dmawait list since that is the only place where * it is supposed to be enqueued. */ xchg(&pq->state, SDMA_PKT_Q_DEFERRED); - write_seqlock(&sde->waitlock); if (list_empty(&pq->busy.list)) { iowait_get_priority(&pq->busy); iowait_queue(pkts_sent, &pq->busy, &sde->dmawait); @@ -151,6 +147,7 @@ static int defer_packet_queue( write_sequnlock(&sde->waitlock); return -EBUSY; eagain: + write_sequnlock(&sde->waitlock); return -EAGAIN; } @@ -804,7 +801,6 @@ static int user_sdma_send_pkts(struct user_sdma_request *req, u16 maxpkts) tx->flags = 0; tx->req = req; - tx->busycount = 0; INIT_LIST_HEAD(&tx->list); /* diff --git a/drivers/infiniband/hw/hfi1/user_sdma.h b/drivers/infiniband/hw/hfi1/user_sdma.h index 14dfd75..4d8510b0 100644 --- a/drivers/infiniband/hw/hfi1/user_sdma.h +++ b/drivers/infiniband/hw/hfi1/user_sdma.h @@ -245,7 +245,6 @@ struct user_sdma_txreq { struct list_head list; struct user_sdma_request *req; u16 flags; - unsigned int busycount; u16 seqnum; };