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IB/hfi1: Close PSM sdma_progress sleep window 

The call to sdma_progress() is called outside the wait lock.

In this case, there is a race condition where sdma_progress() can return
false and the sdma_engine can idle.  If that happens, there will be no
more sdma interrupts to cause the wakeup and the user_sdma xmit will hang.

Fix by moving the lock to enclose the sdma_progress() call.

Also, delete busycount. The need for this was removed by:
commit bcad29137a ("IB/hfi1: Serve the most starved iowait entry first")

Cc: <stable@vger.kernel.org>
Fixes: 7724105686 ("IB/hfi1: add driver files")
Reviewed-by: Gary Leshner <Gary.S.Leshner@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Mike Marciniszyn 2019-06-07 08:25:31 -04:00 committed by Jason Gunthorpe
parent 5f90677ed3
commit da9de5f852
2 changed files with 4 additions and 9 deletions
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10
drivers/infiniband/hw/hfi1/user_sdma.c
View File

@ -130,20 +130,16 @@ static int defer_packet_queue(
{
struct hfi1_user_sdma_pkt_q *pq =
container_of(wait->iow, struct hfi1_user_sdma_pkt_q, busy);
struct user_sdma_txreq *tx =
container_of(txreq, struct user_sdma_txreq, txreq);
if (sdma_progress(sde, seq, txreq)) {
if (tx->busycount++ < MAX_DEFER_RETRY_COUNT)
write_seqlock(&sde->waitlock);
if (sdma_progress(sde, seq, txreq))
goto eagain;
}
/*
* We are assuming that if the list is enqueued somewhere, it
* is to the dmawait list since that is the only place where
* it is supposed to be enqueued.
*/
xchg(&pq->state, SDMA_PKT_Q_DEFERRED);
write_seqlock(&sde->waitlock);
if (list_empty(&pq->busy.list)) {
iowait_get_priority(&pq->busy);
iowait_queue(pkts_sent, &pq->busy, &sde->dmawait);
@ -151,6 +147,7 @@ static int defer_packet_queue(
write_sequnlock(&sde->waitlock);
return -EBUSY;
eagain:
write_sequnlock(&sde->waitlock);
return -EAGAIN;
}
@ -804,7 +801,6 @@ static int user_sdma_send_pkts(struct user_sdma_request *req, u16 maxpkts)
tx->flags = 0;
tx->req = req;
tx->busycount = 0;
INIT_LIST_HEAD(&tx->list);
/*

1
drivers/infiniband/hw/hfi1/user_sdma.h
View File

@ -245,7 +245,6 @@ struct user_sdma_txreq {
struct list_head list;
struct user_sdma_request *req;
u16 flags;
unsigned int busycount;
u16 seqnum;
};