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Commit 60df2958 authored by Mike Marciniszyn's avatar Mike Marciniszyn Committed by Doug Ledford
Browse files

IB/hfi1: Fix PIO wakeup timing hole 



There is a timing hole if there had been greater than
PIO_WAIT_BATCH_SIZE waiters.  This code will dispatch the first
batch but leave the others in the queue.   If the restarted waiters
don't in turn wait on a buffer, there is a hang.

Fix by forcing a return when the QP queue is non-empty.

Reviewed-by: default avatarVennila Megavannan <vennila.megavannan@intel.com>
Signed-off-by: default avatarMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
parent 5326dfbf

drivers/staging/rdma/hfi1/pio.c

+7 −5
Original line number Original line Diff line number Diff line
@@ -1545,7 +1545,7 @@ static void sc_piobufavail(struct send_context *sc) 
		struct iowait *wait;

		struct iowait *wait;





		if (n == ARRAY_SIZE(qps))

		if (n == ARRAY_SIZE(qps))

			goto full;

			break;

		wait = list_first_entry(list, struct iowait, list);

		wait = list_first_entry(list, struct iowait, list);

		qp = iowait_to_qp(wait);

		qp = iowait_to_qp(wait);

		priv = qp->priv;

		priv = qp->priv;
@@ -1554,12 +1554,14 @@ static void sc_piobufavail(struct send_context *sc) 
		qps[n++] = qp;

		qps[n++] = qp;

	}

	}

	/*

	/*

	 * Counting: only call wantpiobuf_intr() if there were waiters and they

	 * If there had been waiters and there are more

	 * are now all gone.

	 * insure that we redo the force to avoid a potential hang.

	 */

	 */

	if (n)

	if (n) {

		hfi1_sc_wantpiobuf_intr(sc, 0);

		hfi1_sc_wantpiobuf_intr(sc, 0);

full:

		if (!list_empty(list))

			hfi1_sc_wantpiobuf_intr(sc, 1);

	}

	write_sequnlock_irqrestore(&dev->iowait_lock, flags);

	write_sequnlock_irqrestore(&dev->iowait_lock, flags);





	for (i = 0; i < n; i++)

	for (i = 0; i < n; i++)