[PATCH rdma-rc] RDMA/bnxt_re: Fix budget handling of notification queue

[PATCH rdma-rc] RDMA/bnxt_re: Fix budget handling of notification queue

[Kalesh AP]

From: Kashyap Desai <kashyap.desai@broadcom.com>

The cited commit in Fixes tag introduced a bug which can cause hang
of completion queue processing because of notification queue budget
goes to zero.

Found while doing nfs over rdma mount and umount.
Below message is noticed because of the existing bug.

kernel: cm_destroy_id_wait_timeout: cm_id=00000000ff6c6cc6 timed out. state 11 -> 0, refcnt=1

Fix to handle this issue -
Driver will not change nq->budget upon create and destroy of cq and srq
rdma resources.

Fixes: cb97b377a135 ("RDMA/bnxt_re: Refurbish CQ to NQ hash calculation")
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
---
 drivers/infiniband/hw/bnxt_re/ib_verbs.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/infiniband/hw/bnxt_re/ib_verbs.c b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
index 6f5db32082dd..cb9b820c613d 100644
--- a/drivers/infiniband/hw/bnxt_re/ib_verbs.c
+++ b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
@@ -1784,8 +1784,6 @@ int bnxt_re_destroy_srq(struct ib_srq *ib_srq, struct ib_udata *udata)
 	bnxt_qplib_destroy_srq(&rdev->qplib_res, qplib_srq);
 	ib_umem_release(srq->umem);
 	atomic_dec(&rdev->stats.res.srq_count);
-	if (nq)
-		nq->budget--;
 	return 0;
 }
 
@@ -1907,8 +1905,6 @@ int bnxt_re_create_srq(struct ib_srq *ib_srq,
 			goto fail;
 		}
 	}
-	if (nq)
-		nq->budget++;
 	active_srqs = atomic_inc_return(&rdev->stats.res.srq_count);
 	if (active_srqs > rdev->stats.res.srq_watermark)
 		rdev->stats.res.srq_watermark = active_srqs;
@@ -3078,7 +3074,6 @@ int bnxt_re_destroy_cq(struct ib_cq *ib_cq, struct ib_udata *udata)
 	ib_umem_release(cq->umem);
 
 	atomic_dec(&rdev->stats.res.cq_count);
-	nq->budget--;
 	kfree(cq->cql);
 	return 0;
 }
-- 
2.43.5

Re: [PATCH rdma-rc] RDMA/bnxt_re: Fix budget handling of notification queue

[Jason Gunthorpe]

On Mon, Mar 24, 2025 at 09:39:35AM +0530, Kalesh AP wrote:
> From: Kashyap Desai <kashyap.desai@broadcom.com>
> 
> The cited commit in Fixes tag introduced a bug which can cause hang
> of completion queue processing because of notification queue budget
> goes to zero.
> 
> Found while doing nfs over rdma mount and umount.
> Below message is noticed because of the existing bug.
> 
> kernel: cm_destroy_id_wait_timeout: cm_id=00000000ff6c6cc6 timed out. state 11 -> 0, refcnt=1
> 
> Fix to handle this issue -
> Driver will not change nq->budget upon create and destroy of cq and srq
> rdma resources.
> 
> Fixes: cb97b377a135 ("RDMA/bnxt_re: Refurbish CQ to NQ hash calculation")
> Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
> Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
> ---
>  drivers/infiniband/hw/bnxt_re/ib_verbs.c | 5 -----
>  1 file changed, 5 deletions(-)

Applied to for-rc, thanks

Jason