Commit b6eac931 authored by Mike Marciniszyn's avatar Mike Marciniszyn Committed by Doug Ledford
Browse files

IB/hfi1: Prevent kernel QP post send hard lockups 



The driver progress routines can call cond_resched() when
a timeslice is exhausted and irqs are enabled.

If the ULP had been holding a spin lock without disabling irqs and
the post send directly called the progress routine, the cond_resched()
could yield allowing another thread from the same ULP to deadlock
on that same lock.

Correct by replacing the current hfi1_do_send() calldown with a unique
one for post send and adding an argument to hfi1_do_send() to indicate
that the send engine is running in a thread.   If the routine is not
running in a thread, avoid calling cond_resched().

CC: <stable@vger.kernel.org> # 4.7.x-
Fixes: Commit 831464ce ("IB/hfi1: Don't call cond_resched in atomic mode when sending packets")
Reviewed-by: default avatarDennis Dalessandro <dennis.dalessandro@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 avatarDoug Ledford <dledford@redhat.com>
parent 3d591099

drivers/infiniband/hw/hfi1/ruc.c

+16 −10
Original line number Diff line number Diff line 
/*

 * Copyright(c) 2015, 2016 Intel Corporation.

 * Copyright(c) 2015 - 2017 Intel Corporation.

 *

 * This file is provided under a dual BSD/GPLv2 license.  When using or

 * redistributing this file, you may do so under either license.
@@ -784,23 +784,29 @@ void hfi1_make_ruc_header(struct rvt_qp *qp, struct ib_other_headers *ohdr, 
/* when sending, force a reschedule every one of these periods */

#define SEND_RESCHED_TIMEOUT (5 * HZ)  /* 5s in jiffies */



void hfi1_do_send_from_rvt(struct rvt_qp *qp)

{

	hfi1_do_send(qp, false);

}



void _hfi1_do_send(struct work_struct *work)

{

	struct iowait *wait = container_of(work, struct iowait, iowork);

	struct rvt_qp *qp = iowait_to_qp(wait);



	hfi1_do_send(qp);

	hfi1_do_send(qp, true);

}



/**

 * hfi1_do_send - perform a send on a QP

 * @work: contains a pointer to the QP

 * @in_thread: true if in a workqueue thread

 *

 * Process entries in the send work queue until credit or queue is

 * exhausted.  Only allow one CPU to send a packet per QP.

 * Otherwise, two threads could send packets out of order.

 */

void hfi1_do_send(struct rvt_qp *qp)

void hfi1_do_send(struct rvt_qp *qp, bool in_thread)

{

	struct hfi1_pkt_state ps;

	struct hfi1_qp_priv *priv = qp->priv;
@@ -868,7 +874,9 @@ void hfi1_do_send(struct rvt_qp *qp) 
			qp->s_hdrwords = 0;

			/* allow other tasks to run */

			if (unlikely(time_after(jiffies, timeout))) {

				if (workqueue_congested(cpu,

				if (!in_thread ||

				    workqueue_congested(

						cpu,

						ps.ppd->hfi1_wq)) {

					spin_lock_irqsave(

						&qp->s_lock,
@@ -882,11 +890,9 @@ void hfi1_do_send(struct rvt_qp *qp) 
						*ps.ppd->dd->send_schedule);

					return;

				}

				if (!irqs_disabled()) {

				cond_resched();

				this_cpu_inc(

					*ps.ppd->dd->send_schedule);

				}

				timeout = jiffies + (timeout_int) / 8;

			}

			spin_lock_irqsave(&qp->s_lock, ps.flags);

drivers/infiniband/hw/hfi1/verbs.c

+2 −2
Original line number Diff line number Diff line 
/*

 * Copyright(c) 2015, 2016 Intel Corporation.

 * Copyright(c) 2015 - 2017 Intel Corporation.

 *

 * This file is provided under a dual BSD/GPLv2 license.  When using or

 * redistributing this file, you may do so under either license.
@@ -1820,7 +1820,7 @@ int hfi1_register_ib_device(struct hfi1_devdata *dd) 
	dd->verbs_dev.rdi.driver_f.qp_priv_free = qp_priv_free;

	dd->verbs_dev.rdi.driver_f.free_all_qps = free_all_qps;

	dd->verbs_dev.rdi.driver_f.notify_qp_reset = notify_qp_reset;

	dd->verbs_dev.rdi.driver_f.do_send = hfi1_do_send;

	dd->verbs_dev.rdi.driver_f.do_send = hfi1_do_send_from_rvt;

	dd->verbs_dev.rdi.driver_f.schedule_send = hfi1_schedule_send;

	dd->verbs_dev.rdi.driver_f.schedule_send_no_lock = _hfi1_schedule_send;

	dd->verbs_dev.rdi.driver_f.get_pmtu_from_attr = get_pmtu_from_attr;

drivers/infiniband/hw/hfi1/verbs.h

+4 −2
Original line number Diff line number Diff line 
/*

 * Copyright(c) 2015, 2016 Intel Corporation.

 * Copyright(c) 2015 - 2017 Intel Corporation.

 *

 * This file is provided under a dual BSD/GPLv2 license.  When using or

 * redistributing this file, you may do so under either license.
@@ -355,7 +355,9 @@ void hfi1_make_ruc_header(struct rvt_qp *qp, struct ib_other_headers *ohdr, 


void _hfi1_do_send(struct work_struct *work);



void hfi1_do_send(struct rvt_qp *qp);

void hfi1_do_send_from_rvt(struct rvt_qp *qp);



void hfi1_do_send(struct rvt_qp *qp, bool in_thread);



void hfi1_send_complete(struct rvt_qp *qp, struct rvt_swqe *wqe,

			enum ib_wc_status status);

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