From accacb8f51c299965939ac56926d1c718e2691a1 Mon Sep 17 00:00:00 2001 From: Andrew Boyer Date: Wed, 23 Nov 2016 12:39:22 -0500 Subject: [PATCH] IB/rxe: Add support for IB_CQ_REPORT_MISSED_EVENTS Peek at the CQ after arming it so that we can return a hint. This avoids missed completions due to a race between posting CQEs and arming the CQ. For example, CM teardown waits on MAD requests to complete with ib_cq_poll_work(). Without this fix, the last completion might be left on the CQ, hanging the kthread doing the teardown. The console backtraces look like this: [ 4199.911284] Call Trace: [ 4199.911401] [] schedule+0x35/0x80 [ 4199.911556] [] schedule_timeout+0x22f/0x2c0 [ 4199.911727] [] ? __schedule+0x368/0xa20 [ 4199.911891] [] wait_for_completion+0xb3/0x130 [ 4199.912067] [] ? wake_up_q+0x70/0x70 [ 4199.912243] [] cm_destroy_id+0x13d/0x450 [ib_cm] [ 4199.912422] [] ? printk+0x57/0x73 [ 4199.912578] [] ib_destroy_cm_id+0x10/0x20 [ib_cm] [ 4199.912759] [] rdma_destroy_id+0xac/0x340 [rdma_cm] [ 4199.912941] [] 0xffffffffc076f2cc Signed-off-by: Andrew Boyer Signed-off-by: Doug Ledford --- drivers/infiniband/sw/rxe/rxe_verbs.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c index 19841c863daf..de39b0a081de 100644 --- a/drivers/infiniband/sw/rxe/rxe_verbs.c +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c @@ -1007,11 +1007,19 @@ static int rxe_peek_cq(struct ib_cq *ibcq, int wc_cnt) static int rxe_req_notify_cq(struct ib_cq *ibcq, enum ib_cq_notify_flags flags) { struct rxe_cq *cq = to_rcq(ibcq); + unsigned long irq_flags; + int ret = 0; + spin_lock_irqsave(&cq->cq_lock, irq_flags); if (cq->notify != IB_CQ_NEXT_COMP) cq->notify = flags & IB_CQ_SOLICITED_MASK; - return 0; + if ((flags & IB_CQ_REPORT_MISSED_EVENTS) && !queue_empty(cq->queue)) + ret = 1; + + spin_unlock_irqrestore(&cq->cq_lock, irq_flags); + + return ret; } static struct ib_mr *rxe_get_dma_mr(struct ib_pd *ibpd, int access) -- 2.20.1