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Revision 6e474083f3daf3a3546737f5d7d502ad12eb257c authored by Wei Xu on 01 December 2017, 10:10:36 UTC, committed by David S. Miller on 03 December 2017, 02:31:03 UTC 
vhost: fix skb leak in handle_rx()
 
Matthew found a roughly 40% tcp throughput regression with commit
c67df11f(vhost_net: try batch dequing from skb array) as discussed
in the following thread:
https://www.mail-archive.com/netdev@vger.kernel.org/msg187936.html

Eventually we figured out that it was a skb leak in handle_rx()
when sending packets to the VM. This usually happens when a guest
can not drain out vq as fast as vhost fills in, afterwards it sets
off the traffic jam and leaks skb(s) which occurs as no headcount
to send on the vq from vhost side.

This can be avoided by making sure we have got enough headcount
before actually consuming a skb from the batched rx array while
transmitting, which is simply done by moving checking the zero
headcount a bit ahead.

Signed-off-by: Wei Xu <wexu@redhat.com>
Reported-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent fa935ca
Raw File
sa1100_h3600.c 
// SPDX-License-Identifier: GPL-2.0
/*
 * drivers/pcmcia/sa1100_h3600.c
 *
 * PCMCIA implementation routines for H3600
 *
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/gpio.h>

#include <mach/hardware.h>
#include <asm/irq.h>
#include <asm/mach-types.h>
#include <mach/h3xxx.h>

#include "sa1100_generic.h"

static int h3600_pcmcia_hw_init(struct soc_pcmcia_socket *skt)
{
	int err;

	switch (skt->nr) {
	case 0:
		skt->stat[SOC_STAT_CD].gpio = H3XXX_GPIO_PCMCIA_CD0;
		skt->stat[SOC_STAT_CD].name = "PCMCIA CD0";
		skt->stat[SOC_STAT_RDY].gpio = H3XXX_GPIO_PCMCIA_IRQ0;
		skt->stat[SOC_STAT_RDY].name = "PCMCIA IRQ0";

		err = gpio_request(H3XXX_EGPIO_OPT_NVRAM_ON, "OPT NVRAM ON");
		if (err)
			goto err01;
		err = gpio_direction_output(H3XXX_EGPIO_OPT_NVRAM_ON, 0);
		if (err)
			goto err03;
		err = gpio_request(H3XXX_EGPIO_OPT_ON, "OPT ON");
		if (err)
			goto err03;
		err = gpio_direction_output(H3XXX_EGPIO_OPT_ON, 0);
		if (err)
			goto err04;
		err = gpio_request(H3XXX_EGPIO_OPT_RESET, "OPT RESET");
		if (err)
			goto err04;
		err = gpio_direction_output(H3XXX_EGPIO_OPT_RESET, 0);
		if (err)
			goto err05;
		err = gpio_request(H3XXX_EGPIO_CARD_RESET, "PCMCIA CARD RESET");
		if (err)
			goto err05;
		err = gpio_direction_output(H3XXX_EGPIO_CARD_RESET, 0);
		if (err)
			goto err06;
		break;
	case 1:
		skt->stat[SOC_STAT_CD].gpio = H3XXX_GPIO_PCMCIA_CD1;
		skt->stat[SOC_STAT_CD].name = "PCMCIA CD1";
		skt->stat[SOC_STAT_RDY].gpio = H3XXX_GPIO_PCMCIA_IRQ1;
		skt->stat[SOC_STAT_RDY].name = "PCMCIA IRQ1";
		break;
	}
	return 0;

err06:	gpio_free(H3XXX_EGPIO_CARD_RESET);
err05:	gpio_free(H3XXX_EGPIO_OPT_RESET);
err04:	gpio_free(H3XXX_EGPIO_OPT_ON);
err03:	gpio_free(H3XXX_EGPIO_OPT_NVRAM_ON);
err01:	gpio_free(H3XXX_GPIO_PCMCIA_IRQ0);
	return err;
}

static void h3600_pcmcia_hw_shutdown(struct soc_pcmcia_socket *skt)
{
	switch (skt->nr) {
	case 0:
		/* Disable CF bus: */
		gpio_set_value(H3XXX_EGPIO_OPT_NVRAM_ON, 0);
		gpio_set_value(H3XXX_EGPIO_OPT_ON, 0);
		gpio_set_value(H3XXX_EGPIO_OPT_RESET, 1);

		gpio_free(H3XXX_EGPIO_CARD_RESET);
		gpio_free(H3XXX_EGPIO_OPT_RESET);
		gpio_free(H3XXX_EGPIO_OPT_ON);
		gpio_free(H3XXX_EGPIO_OPT_NVRAM_ON);
		break;
	case 1:
		break;
	}
}

static void
h3600_pcmcia_socket_state(struct soc_pcmcia_socket *skt, struct pcmcia_state *state)
{
	state->bvd1 = 0;
	state->bvd2 = 0;
	state->vs_3v = 0;
	state->vs_Xv = 0;
}

static int
h3600_pcmcia_configure_socket(struct soc_pcmcia_socket *skt, const socket_state_t *state)
{
	if (state->Vcc != 0 && state->Vcc != 33 && state->Vcc != 50) {
		printk(KERN_ERR "h3600_pcmcia: unrecognized Vcc %u.%uV\n",
		       state->Vcc / 10, state->Vcc % 10);
		return -1;
	}

	gpio_set_value(H3XXX_EGPIO_CARD_RESET, !!(state->flags & SS_RESET));

	/* Silently ignore Vpp, output enable, speaker enable. */

	return 0;
}

static void h3600_pcmcia_socket_init(struct soc_pcmcia_socket *skt)
{
	/* Enable CF bus: */
	gpio_set_value(H3XXX_EGPIO_OPT_NVRAM_ON, 1);
	gpio_set_value(H3XXX_EGPIO_OPT_ON, 1);
	gpio_set_value(H3XXX_EGPIO_OPT_RESET, 0);

	msleep(10);
}

static void h3600_pcmcia_socket_suspend(struct soc_pcmcia_socket *skt)
{
	/*
	 * FIXME:  This doesn't fit well.  We don't have the mechanism in
	 * the generic PCMCIA layer to deal with the idea of two sockets
	 * on one bus.  We rely on the cs.c behaviour shutting down
	 * socket 0 then socket 1.
	 */
	if (skt->nr == 1) {
		gpio_set_value(H3XXX_EGPIO_OPT_ON, 0);
		gpio_set_value(H3XXX_EGPIO_OPT_NVRAM_ON, 0);
		/* hmm, does this suck power? */
		gpio_set_value(H3XXX_EGPIO_OPT_RESET, 1);
	}
}

struct pcmcia_low_level h3600_pcmcia_ops = { 
	.owner			= THIS_MODULE,
	.hw_init		= h3600_pcmcia_hw_init,
	.hw_shutdown		= h3600_pcmcia_hw_shutdown,
	.socket_state		= h3600_pcmcia_socket_state,
	.configure_socket	= h3600_pcmcia_configure_socket,

	.socket_init		= h3600_pcmcia_socket_init,
	.socket_suspend		= h3600_pcmcia_socket_suspend,
};

int pcmcia_h3600_init(struct device *dev)
{
	int ret = -ENODEV;

	if (machine_is_h3600() || machine_is_h3100())
		ret = sa11xx_drv_pcmcia_probe(dev, &h3600_pcmcia_ops, 0, 2);

	return ret;
}
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