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IB/hfi1: Avoid hardlockup with flushlist_lock

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[ Upstream commit cf131a8196 ]

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.

Fixes: 7724105686 ("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>
This commit is contained in:
Mike Marciniszyn 2019-06-14 12:32:26 -04:00 • committed by Greg Kroah-Hartman
commit 90ca4912e5
1 changed files with 3 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

9
drivers/infiniband/hw/hfi1/sdma.c
View file

@ -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)
@ -2426,7 +2423,7 @@ unlock_noconn:
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:
@ -2526,7 +2523,7 @@ unlock_noconn:
}
}
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: