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IB/hfi1: Fix PIO wakeup timing hole

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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: Vennila Megavannan <vennila.megavannan@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
This commit is contained in:
Mike Marciniszyn 2016-03-07 11:35:30 -08:00 committed by Doug Ledford
parent 5326dfbf00
commit 60df29581f
1 changed files with 7 additions and 5 deletions
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12
drivers/staging/rdma/hfi1/pio.c
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@ -1545,7 +1545,7 @@ static void sc_piobufavail(struct send_context *sc)
struct iowait *wait;
if (n == ARRAY_SIZE(qps))
goto full;
break;
wait = list_first_entry(list, struct iowait, list);
qp = iowait_to_qp(wait);
priv = qp->priv;
@ -1554,12 +1554,14 @@ static void sc_piobufavail(struct send_context *sc)
qps[n++] = qp;
}
/*
* Counting: only call wantpiobuf_intr() if there were waiters and they
* are now all gone.
* If there had been waiters and there are more
* insure that we redo the force to avoid a potential hang.
*/
if (n)
if (n) {
hfi1_sc_wantpiobuf_intr(sc, 0);
full:
if (!list_empty(list))
hfi1_sc_wantpiobuf_intr(sc, 1);
}
write_sequnlock_irqrestore(&dev->iowait_lock, flags);
for (i = 0; i < n; i++)