Commit 960ebe97 authored by Bob Pearson's avatar Bob Pearson Committed by Jason Gunthorpe
Browse files

RDMA/rxe: Remove __rxe_do_task() 

The subroutine __rxe_do_task is not thread safe and it has no way to
guarantee that the tasks, which are designed with the assumption that they
are non-reentrant, are not reentered. All of its uses are non-performance
critical.

This patch replaces calls to __rxe_do_task with calls to
rxe_sched_task. It also removes irrelevant or unneeded if tests.

Instead of calling the task machinery a single call to the tasklet
function (rxe_requester, etc.) is sufficient to draing the queues if task
execution has been disabled or stopped.

Together these changes allow the removal of __rxe_do_task.

Link: https://lore.kernel.org/r/20230304174533.11296-7-rpearsonhpe@gmail.com


Signed-off-by: default avatarIan Ziemba <ian.ziemba@hpe.com>
Signed-off-by: default avatarBob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent a246aa2e

drivers/infiniband/sw/rxe/rxe_qp.c

+17 −39
Original line number Diff line number Diff line
@@ -473,29 +473,23 @@ static void rxe_qp_reset(struct rxe_qp *qp) 
{

	/* stop tasks from running */

	rxe_disable_task(&qp->resp.task);



	/* stop request/comp */

	if (qp->sq.queue) {

		if (qp_type(qp) == IB_QPT_RC)

	rxe_disable_task(&qp->comp.task);

	rxe_disable_task(&qp->req.task);

	}



	/* move qp to the reset state */

	qp->req.state = QP_STATE_RESET;

	qp->comp.state = QP_STATE_RESET;

	qp->resp.state = QP_STATE_RESET;



	/* let state machines reset themselves drain work and packet queues

	 * etc.

	 */

	__rxe_do_task(&qp->resp.task);

	/* drain work and packet queuesc */

	rxe_requester(qp);

	rxe_completer(qp);

	rxe_responder(qp);



	if (qp->sq.queue) {

		__rxe_do_task(&qp->comp.task);

		__rxe_do_task(&qp->req.task);

	if (qp->rq.queue)

		rxe_queue_reset(qp->rq.queue);

	if (qp->sq.queue)

		rxe_queue_reset(qp->sq.queue);

	}



	/* cleanup attributes */

	atomic_set(&qp->ssn, 0);
@@ -518,14 +512,9 @@ static void rxe_qp_reset(struct rxe_qp *qp) 


	/* reenable tasks */

	rxe_enable_task(&qp->resp.task);



	if (qp->sq.queue) {

		if (qp_type(qp) == IB_QPT_RC)

	rxe_enable_task(&qp->comp.task);



	rxe_enable_task(&qp->req.task);

}

}



/* drain the send queue */

static void rxe_qp_drain(struct rxe_qp *qp)
@@ -533,10 +522,7 @@ static void rxe_qp_drain(struct rxe_qp *qp) 
	if (qp->sq.queue) {

		if (qp->req.state != QP_STATE_DRAINED) {

			qp->req.state = QP_STATE_DRAIN;

			if (qp_type(qp) == IB_QPT_RC)

			rxe_sched_task(&qp->comp.task);

			else

				__rxe_do_task(&qp->comp.task);

			rxe_sched_task(&qp->req.task);

		}

	}
@@ -552,11 +538,7 @@ void rxe_qp_error(struct rxe_qp *qp) 


	/* drain work and packet queues */

	rxe_sched_task(&qp->resp.task);



	if (qp_type(qp) == IB_QPT_RC)

	rxe_sched_task(&qp->comp.task);

	else

		__rxe_do_task(&qp->comp.task);

	rxe_sched_task(&qp->req.task);

}
@@ -773,24 +755,20 @@ static void rxe_qp_do_cleanup(struct work_struct *work) 


	qp->valid = 0;

	qp->qp_timeout_jiffies = 0;

	rxe_cleanup_task(&qp->resp.task);



	if (qp_type(qp) == IB_QPT_RC) {

		del_timer_sync(&qp->retrans_timer);

		del_timer_sync(&qp->rnr_nak_timer);

	}



	rxe_cleanup_task(&qp->resp.task);

	rxe_cleanup_task(&qp->req.task);

	rxe_cleanup_task(&qp->comp.task);



	/* flush out any receive wr's or pending requests */

	if (qp->req.task.func)

		__rxe_do_task(&qp->req.task);



	if (qp->sq.queue) {

		__rxe_do_task(&qp->comp.task);

		__rxe_do_task(&qp->req.task);

	}

	rxe_requester(qp);

	rxe_completer(qp);

	rxe_responder(qp);



	if (qp->sq.queue)

		rxe_queue_cleanup(qp->sq.queue);

drivers/infiniband/sw/rxe/rxe_task.c

+0 −13
Original line number Diff line number Diff line
@@ -6,19 +6,6 @@ 


#include "rxe.h"



int __rxe_do_task(struct rxe_task *task)



{

	int ret;



	while ((ret = task->func(task->qp)) == 0)

		;



	task->ret = ret;



	return ret;

}



/*

 * this locking is due to a potential race where

 * a second caller finds the task already running

drivers/infiniband/sw/rxe/rxe_task.h

+0 −6
Original line number Diff line number Diff line
@@ -39,12 +39,6 @@ int rxe_init_task(struct rxe_task *task, struct rxe_qp *qp, 
/* cleanup task */

void rxe_cleanup_task(struct rxe_task *task);



/*

 * raw call to func in loop without any checking

 * can call when tasklets are disabled

 */

int __rxe_do_task(struct rxe_task *task);



void rxe_run_task(struct rxe_task *task);



void rxe_sched_task(struct rxe_task *task);