+++ /dev/null
-From fd48a90b6f844fc05f7b78e71087127608b7907f Mon Sep 17 00:00:00 2001
-From: Mike Marciniszyn <mike.marciniszyn@intel.com>
-Date: Mon, 24 Jun 2019 12:14:29 -0400
-Subject: IB/hfi1: Avoid hardlockup with flushlist_lock
-
-commit cf131a81967583ae737df6383a0893b9fee75b4e upstream.
-
-Heavy contention of the sde flushlist_lock can cause hard lockups at
-extreme scale when the flushing logic is under stress.
-
-Mitigate by replacing the item at a time copy to the local list with
-an O(1) list_splice_init() and using the high priority work queue to
-do the flushes.
-
-Ported to linux-4.14.y.
-
-Fixes: 7724105686e7 ("IB/hfi1: add driver files")
-Cc: <stable@vger.kernel.org>
-Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
-Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
-Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
-Signed-off-by: Doug Ledford <dledford@redhat.com>
-Signed-off-by: Sasha Levin <sashal@kernel.org>
----
- drivers/infiniband/hw/hfi1/sdma.c | 9 +++------
- 1 file changed, 3 insertions(+), 6 deletions(-)
-
-diff --git a/drivers/infiniband/hw/hfi1/sdma.c b/drivers/infiniband/hw/hfi1/sdma.c
-index 6781bcdb10b3..ec613d5a6533 100644
---- a/drivers/infiniband/hw/hfi1/sdma.c
-+++ b/drivers/infiniband/hw/hfi1/sdma.c
-@@ -410,10 +410,7 @@ static void sdma_flush(struct sdma_engine *sde)
- sdma_flush_descq(sde);
- spin_lock_irqsave(&sde->flushlist_lock, flags);
- /* copy flush list */
-- list_for_each_entry_safe(txp, txp_next, &sde->flushlist, list) {
-- list_del_init(&txp->list);
-- list_add_tail(&txp->list, &flushlist);
-- }
-+ list_splice_init(&sde->flushlist, &flushlist);
- spin_unlock_irqrestore(&sde->flushlist_lock, flags);
- /* flush from flush list */
- list_for_each_entry_safe(txp, txp_next, &flushlist, list)
-@@ -2437,7 +2434,7 @@ int sdma_send_txreq(struct sdma_engine *sde,
- wait->tx_count++;
- wait->count += tx->num_desc;
- }
-- schedule_work(&sde->flush_worker);
-+ queue_work_on(sde->cpu, system_highpri_wq, &sde->flush_worker);
- ret = -ECOMM;
- goto unlock;
- nodesc:
-@@ -2537,7 +2534,7 @@ int sdma_send_txlist(struct sdma_engine *sde, struct iowait *wait,
- }
- }
- spin_unlock(&sde->flushlist_lock);
-- schedule_work(&sde->flush_worker);
-+ queue_work_on(sde->cpu, system_highpri_wq, &sde->flush_worker);
- ret = -ECOMM;
- goto update_tail;
- nodesc:
---
-2.20.1
-