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Commit adddc32d authored by Sowmini Varadhan's avatar Sowmini Varadhan Committed by David S. Miller
Browse files

sunvnet: Do not spin in an infinite loop when vio_ldc_send() returns EAGAIN 



ldc_rx -> vnet_rx -> .. -> vnet_walk_rx->vnet_send_ack should not
spin into an infinite loop waiting  EAGAIN to lift.

The sender could have sent us a burst, and gone to lunch without
doing any more ldc_read()'s. That should not cause the receiver to
loop infinitely till soft-lockup kicks in.

Similarly __vnet_tx_trigger should only loop on EAGAIN a finite
number of times. The caller (vnet_start_xmit()) already has code
to reset the dring state and bail on errors from __vnet_tx_trigger

Signed-off-by: default avatarSowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: default avatarRaghuram Kothakota <raghuram.kothakota@oracle.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1f6394e3

drivers/net/ethernet/sun/sunvnet.c

+16 −0
Original line number Diff line number Diff line
@@ -32,6 +32,11 @@ MODULE_DESCRIPTION("Sun LDOM virtual network driver"); 
MODULE_LICENSE("GPL");

MODULE_VERSION(DRV_MODULE_VERSION);



/* Heuristic for the number of times to exponentially backoff and

 * retry sending an LDC trigger when EAGAIN is encountered

 */

#define	VNET_MAX_RETRIES	10



/* Ordered from largest major to lowest */

static struct vio_version vnet_versions[] = {

	{ .major = 1, .minor = 0 },
@@ -260,6 +265,7 @@ static int vnet_send_ack(struct vnet_port *port, struct vio_dring_state *dr, 
		.state			= vio_dring_state,

	};

	int err, delay;

	int retries = 0;



	hdr.seq = dr->snd_nxt;

	delay = 1;
@@ -272,6 +278,13 @@ static int vnet_send_ack(struct vnet_port *port, struct vio_dring_state *dr, 
		udelay(delay);

		if ((delay <<= 1) > 128)

			delay = 128;

		if (retries++ > VNET_MAX_RETRIES) {

			pr_info("ECONNRESET %x:%x:%x:%x:%x:%x\n",

				port->raddr[0], port->raddr[1],

				port->raddr[2], port->raddr[3],

				port->raddr[4], port->raddr[5]);

			err = -ECONNRESET;

		}

	} while (err == -EAGAIN);



	return err;
@@ -593,6 +606,7 @@ static int __vnet_tx_trigger(struct vnet_port *port) 
		.end_idx		= (u32) -1,

	};

	int err, delay;

	int retries = 0;



	hdr.seq = dr->snd_nxt;

	delay = 1;
@@ -605,6 +619,8 @@ static int __vnet_tx_trigger(struct vnet_port *port) 
		udelay(delay);

		if ((delay <<= 1) > 128)

			delay = 128;

		if (retries++ > VNET_MAX_RETRIES)

			break;

	} while (err == -EAGAIN);



	return err;