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Commit a8782ce0 authored by Mike Marciniszyn's avatar Mike Marciniszyn Committed by Greg Kroah-Hartman
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IB/hfi1: Close PSM sdma_progress sleep window 



commit da9de5f8527f4b9efc82f967d29a583318c034c7 upstream.

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 bcad2913 ("IB/hfi1: Serve the most starved iowait entry first")

Ported to linux-4.19.y.

Cc: <stable@vger.kernel.org>
Fixes: 77241056 ("IB/hfi1: add driver files")
Reviewed-by: default avatarGary Leshner <Gary.S.Leshner@intel.com>
Signed-off-by: default avatarMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: default avatarDennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent fec1a13b

drivers/infiniband/hw/hfi1/user_sdma.c

+4 −8
Original line number Diff line number Diff line
@@ -132,25 +132,22 @@ static int defer_packet_queue( 
	struct hfi1_user_sdma_pkt_q *pq =

		container_of(wait, struct hfi1_user_sdma_pkt_q, busy);

	struct hfi1_ibdev *dev = &pq->dd->verbs_dev;

	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(&dev->iowait_lock);

	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(&dev->iowait_lock);

	if (list_empty(&pq->busy.list))

		iowait_queue(pkts_sent, &pq->busy, &sde->dmawait);

	write_sequnlock(&dev->iowait_lock);

	return -EBUSY;

eagain:

	write_sequnlock(&dev->iowait_lock);

	return -EAGAIN;

}
@@ -803,7 +800,6 @@ static int user_sdma_send_pkts(struct user_sdma_request *req, unsigned maxpkts) 


		tx->flags = 0;

		tx->req = req;

		tx->busycount = 0;

		INIT_LIST_HEAD(&tx->list);



		/*

drivers/infiniband/hw/hfi1/user_sdma.h

+0 −1
Original line number Diff line number Diff line
@@ -245,7 +245,6 @@ struct user_sdma_txreq { 
	struct list_head list;

	struct user_sdma_request *req;

	u16 flags;

	unsigned int busycount;

	u64 seqnum;

};