RDMA/rxe: Fix rxe_cq_post

A recent patch replaced a tasklet execution of cq->comp_handler by a
direct call. While this made sense it let changes to cq->notify state be
unprotected and assumed that the cq completion machinery and the ulp done
callbacks were reentrant. The result is that in some cases completion
events can be lost. This patch moves the cq->comp_handler call inside of
the spinlock in rxe_cq_post which solves both issues. This is compatible
with the matching code in the request notify verb.

Fixes: 78b26a335310 ("RDMA/rxe: Remove tasklet call from rxe_cq.c")
Link: https://lore.kernel.org/r/20230612155032.17036-1-rpearsonhpe@gmail.com
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/sw/rxe/rxe_cq.c b/drivers/infiniband/sw/rxe/rxe_cq.c
index 20ff0c0c46052efdcc6fc896be6d0667cda81da2..6ca2a05b6a2ab262594b7a3fbbc799f86fba4eff 100644 (file)
--- a/drivers/infiniband/sw/rxe/rxe_cq.c
+++ b/drivers/infiniband/sw/rxe/rxe_cq.c
@@ -113,8 +113,6 @@ int rxe_cq_post(struct rxe_cq *cq, struct rxe_cqe *cqe, int solicited)
 
        queue_advance_producer(cq->queue, QUEUE_TYPE_TO_CLIENT);
 
-       spin_unlock_irqrestore(&cq->cq_lock, flags);
-
        if ((cq->notify == IB_CQ_NEXT_COMP) ||
            (cq->notify == IB_CQ_SOLICITED && solicited)) {
                cq->notify = 0;
@@ -122,6 +120,8 @@ int rxe_cq_post(struct rxe_cq *cq, struct rxe_cqe *cqe, int solicited)
                cq->ibcq.comp_handler(&cq->ibcq, cq->ibcq.cq_context);
        }
 
+       spin_unlock_irqrestore(&cq->cq_lock, flags);
+
        return 0;
 }