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Commit c53a6ee8 authored by Oliver Hartkopp's avatar Oliver Hartkopp Committed by David S. Miller
Browse files

can: fix slowpath issue in hrtimer callback function 



Due to the loopback functionality in can_send() we can not invoke it
from hardirq context which was done inside the
bcm_tx_timeout_handler() hrtimer callback:

[  700.361154]  [<c012228c>] warn_slowpath+0x80/0xb6
[  700.361163]  [<c013d559>] valid_state+0x125/0x136
[  700.361171]  [<c013d858>] mark_lock+0x18e/0x332
[  700.361180]  [<c013e300>] __lock_acquire+0x12e/0xb1e
[  700.361189]  [<f8ab5915>] bcm_tx_timeout_handler+0x0/0xbc [can_bcm]
[  700.361198]  [<c031e20a>] dev_queue_xmit+0x191/0x479
[  700.361206]  [<c01262a7>] __local_bh_disable+0x2b/0x64
[  700.361213]  [<c031e20a>] dev_queue_xmit+0x191/0x479
[  700.361225]  [<f8aa69a1>] can_send+0xd7/0x11a [can]
[  700.361235]  [<f8ab522b>] bcm_can_tx+0x9d/0xd9 [can_bcm]
[  700.361245]  [<f8ab597f>] bcm_tx_timeout_handler+0x6a/0xbc [can_bcm]
[  700.361255]  [<f8ab5915>] bcm_tx_timeout_handler+0x0/0xbc [can_bcm]
[  700.361263]  [<c0134143>] __run_hrtimer+0x5a/0x86
[  700.361273]  [<f8ab5915>] bcm_tx_timeout_handler+0x0/0xbc [can_bcm]
[  700.361282]  [<c0134a50>] hrtimer_interrupt+0xb9/0x110

This patch moves the rest of the functionality from the hrtimer
callback to the already existing tasklet to fix this slowpath problem.

Signed-off-by: default avatarOliver Hartkopp <oliver@hartkopp.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d57bc36e

net/can/bcm.c

+30 −27
Original line number Diff line number Diff line
@@ -347,6 +347,11 @@ static void bcm_tx_timeout_tsklet(unsigned long data) 
	struct bcm_op *op = (struct bcm_op *)data;

	struct bcm_msg_head msg_head;



	if (op->kt_ival1.tv64 && (op->count > 0)) {



		op->count--;

		if (!op->count && (op->flags & TX_COUNTEVT)) {



			/* create notification to user */

			msg_head.opcode  = TX_EXPIRED;

			msg_head.flags   = op->flags;
@@ -358,40 +363,38 @@ static void bcm_tx_timeout_tsklet(unsigned long data) 


			bcm_send_to_user(op, &msg_head, NULL, 0);

		}



/*

 * bcm_tx_timeout_handler - performes cyclic CAN frame transmissions

 */

static enum hrtimer_restart bcm_tx_timeout_handler(struct hrtimer *hrtimer)

{

	struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);

	enum hrtimer_restart ret = HRTIMER_NORESTART;



	if (op->kt_ival1.tv64 && (op->count > 0)) {



		op->count--;

		if (!op->count && (op->flags & TX_COUNTEVT))

			tasklet_schedule(&op->tsklet);

	}



	if (op->kt_ival1.tv64 && (op->count > 0)) {



		/* send (next) frame */

		bcm_can_tx(op);

		hrtimer_forward(hrtimer, ktime_get(), op->kt_ival1);

		ret = HRTIMER_RESTART;

		hrtimer_start(&op->timer,

			      ktime_add(ktime_get(), op->kt_ival1),

			      HRTIMER_MODE_ABS);



	} else {

		if (op->kt_ival2.tv64) {



			/* send (next) frame */

			bcm_can_tx(op);

			hrtimer_forward(hrtimer, ktime_get(), op->kt_ival2);

			ret = HRTIMER_RESTART;

			hrtimer_start(&op->timer,

				      ktime_add(ktime_get(), op->kt_ival2),

				      HRTIMER_MODE_ABS);

		}

	}

}



	return ret;

/*

 * bcm_tx_timeout_handler - performes cyclic CAN frame transmissions

 */

static enum hrtimer_restart bcm_tx_timeout_handler(struct hrtimer *hrtimer)

{

	struct bcm_op *op = container_of(hrtimer, struct bcm_op, timer);



	tasklet_schedule(&op->tsklet);



	return HRTIMER_NORESTART;

}



/*