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
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
leds-mc13783.c
/*
 * LEDs driver for Freescale MC13783/MC13892/MC34708
 *
 * Copyright (C) 2010 Philippe Rétornaz
 *
 * Based on leds-da903x:
 * Copyright (C) 2008 Compulab, Ltd.
 *      Mike Rapoport <mike@compulab.co.il>
 *
 * Copyright (C) 2006-2008 Marvell International Ltd.
 *      Eric Miao <eric.miao@marvell.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/leds.h>
#include <linux/of.h>
#include <linux/mfd/mc13xxx.h>

struct mc13xxx_led_devtype {
	int	led_min;
	int	led_max;
	int	num_regs;
	u32	ledctrl_base;
};

struct mc13xxx_led {
	struct led_classdev	cdev;
	int			id;
	struct mc13xxx_leds	*leds;
};

struct mc13xxx_leds {
	struct mc13xxx			*master;
	struct mc13xxx_led_devtype	*devtype;
	int				num_leds;
	struct mc13xxx_led		*led;
};

static unsigned int mc13xxx_max_brightness(int id)
{
	if (id >= MC13783_LED_MD && id <= MC13783_LED_KP)
		return 0x0f;
	else if (id >= MC13783_LED_R1 && id <= MC13783_LED_B3)
		return 0x1f;

	return 0x3f;
}

static int mc13xxx_led_set(struct led_classdev *led_cdev,
			    enum led_brightness value)
{
	struct mc13xxx_led *led =
		container_of(led_cdev, struct mc13xxx_led, cdev);
	struct mc13xxx_leds *leds = led->leds;
	unsigned int reg, bank, off, shift;

	switch (led->id) {
	case MC13783_LED_MD:
	case MC13783_LED_AD:
	case MC13783_LED_KP:
		reg = 2;
		shift = 9 + (led->id - MC13783_LED_MD) * 4;
		break;
	case MC13783_LED_R1:
	case MC13783_LED_G1:
	case MC13783_LED_B1:
	case MC13783_LED_R2:
	case MC13783_LED_G2:
	case MC13783_LED_B2:
	case MC13783_LED_R3:
	case MC13783_LED_G3:
	case MC13783_LED_B3:
		off = led->id - MC13783_LED_R1;
		bank = off / 3;
		reg = 3 + bank;
		shift = (off - bank * 3) * 5 + 6;
		break;
	case MC13892_LED_MD:
	case MC13892_LED_AD:
	case MC13892_LED_KP:
		off = led->id - MC13892_LED_MD;
		reg = off / 2;
		shift = 3 + (off - reg * 2) * 12;
		break;
	case MC13892_LED_R:
	case MC13892_LED_G:
	case MC13892_LED_B:
		off = led->id - MC13892_LED_R;
		bank = off / 2;
		reg = 2 + bank;
		shift = (off - bank * 2) * 12 + 3;
		break;
	case MC34708_LED_R:
	case MC34708_LED_G:
		reg = 0;
		shift = 3 + (led->id - MC34708_LED_R) * 12;
		break;
	default:
		BUG();
	}

	return mc13xxx_reg_rmw(leds->master, leds->devtype->ledctrl_base + reg,
			mc13xxx_max_brightness(led->id) << shift,
			value << shift);
}

#ifdef CONFIG_OF
static struct mc13xxx_leds_platform_data __init *mc13xxx_led_probe_dt(
	struct platform_device *pdev)
{
	struct mc13xxx_leds *leds = platform_get_drvdata(pdev);
	struct mc13xxx_leds_platform_data *pdata;
	struct device_node *parent, *child;
	struct device *dev = &pdev->dev;
	int i = 0, ret = -ENODATA;

	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
	if (!pdata)
		return ERR_PTR(-ENOMEM);

	parent = of_get_child_by_name(dev->parent->of_node, "leds");
	if (!parent)
		goto out_node_put;

	ret = of_property_read_u32_array(parent, "led-control",
					 pdata->led_control,
					 leds->devtype->num_regs);
	if (ret)
		goto out_node_put;

	pdata->num_leds = of_get_child_count(parent);

	pdata->led = devm_kzalloc(dev, pdata->num_leds * sizeof(*pdata->led),
				  GFP_KERNEL);
	if (!pdata->led) {
		ret = -ENOMEM;
		goto out_node_put;
	}

	for_each_child_of_node(parent, child) {
		const char *str;
		u32 tmp;

		if (of_property_read_u32(child, "reg", &tmp))
			continue;
		pdata->led[i].id = leds->devtype->led_min + tmp;

		if (!of_property_read_string(child, "label", &str))
			pdata->led[i].name = str;
		if (!of_property_read_string(child, "linux,default-trigger",
					     &str))
			pdata->led[i].default_trigger = str;

		i++;
	}

	pdata->num_leds = i;
	ret = i > 0 ? 0 : -ENODATA;

out_node_put:
	of_node_put(parent);

	return ret ? ERR_PTR(ret) : pdata;
}
#else
static inline struct mc13xxx_leds_platform_data __init *mc13xxx_led_probe_dt(
	struct platform_device *pdev)
{
	return ERR_PTR(-ENOSYS);
}
#endif

static int __init mc13xxx_led_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct mc13xxx_leds_platform_data *pdata = dev_get_platdata(dev);
	struct mc13xxx *mcdev = dev_get_drvdata(dev->parent);
	struct mc13xxx_led_devtype *devtype =
		(struct mc13xxx_led_devtype *)pdev->id_entry->driver_data;
	struct mc13xxx_leds *leds;
	int i, id, ret = -ENODATA;
	u32 init_led = 0;

	leds = devm_kzalloc(dev, sizeof(*leds), GFP_KERNEL);
	if (!leds)
		return -ENOMEM;

	leds->devtype = devtype;
	leds->master = mcdev;
	platform_set_drvdata(pdev, leds);

	if (dev->parent->of_node) {
		pdata = mc13xxx_led_probe_dt(pdev);
		if (IS_ERR(pdata))
			return PTR_ERR(pdata);
	} else if (!pdata)
		return -ENODATA;

	leds->num_leds = pdata->num_leds;

	if ((leds->num_leds < 1) ||
	    (leds->num_leds > (devtype->led_max - devtype->led_min + 1))) {
		dev_err(dev, "Invalid LED count %d\n", leds->num_leds);
		return -EINVAL;
	}

	leds->led = devm_kzalloc(dev, leds->num_leds * sizeof(*leds->led),
				 GFP_KERNEL);
	if (!leds->led)
		return -ENOMEM;

	for (i = 0; i < devtype->num_regs; i++) {
		ret = mc13xxx_reg_write(mcdev, leds->devtype->ledctrl_base + i,
					pdata->led_control[i]);
		if (ret)
			return ret;
	}

	for (i = 0; i < leds->num_leds; i++) {
		const char *name, *trig;

		ret = -EINVAL;

		id = pdata->led[i].id;
		name = pdata->led[i].name;
		trig = pdata->led[i].default_trigger;

		if ((id > devtype->led_max) || (id < devtype->led_min)) {
			dev_err(dev, "Invalid ID %i\n", id);
			break;
		}

		if (init_led & (1 << id)) {
			dev_warn(dev, "LED %i already initialized\n", id);
			break;
		}

		init_led |= 1 << id;
		leds->led[i].id = id;
		leds->led[i].leds = leds;
		leds->led[i].cdev.name = name;
		leds->led[i].cdev.default_trigger = trig;
		leds->led[i].cdev.flags = LED_CORE_SUSPENDRESUME;
		leds->led[i].cdev.brightness_set_blocking = mc13xxx_led_set;
		leds->led[i].cdev.max_brightness = mc13xxx_max_brightness(id);

		ret = led_classdev_register(dev->parent, &leds->led[i].cdev);
		if (ret) {
			dev_err(dev, "Failed to register LED %i\n", id);
			break;
		}
	}

	if (ret)
		while (--i >= 0)
			led_classdev_unregister(&leds->led[i].cdev);

	return ret;
}

static int mc13xxx_led_remove(struct platform_device *pdev)
{
	struct mc13xxx_leds *leds = platform_get_drvdata(pdev);
	int i;

	for (i = 0; i < leds->num_leds; i++)
		led_classdev_unregister(&leds->led[i].cdev);

	return 0;
}

static const struct mc13xxx_led_devtype mc13783_led_devtype = {
	.led_min	= MC13783_LED_MD,
	.led_max	= MC13783_LED_B3,
	.num_regs	= 6,
	.ledctrl_base	= 51,
};

static const struct mc13xxx_led_devtype mc13892_led_devtype = {
	.led_min	= MC13892_LED_MD,
	.led_max	= MC13892_LED_B,
	.num_regs	= 4,
	.ledctrl_base	= 51,
};

static const struct mc13xxx_led_devtype mc34708_led_devtype = {
	.led_min	= MC34708_LED_R,
	.led_max	= MC34708_LED_G,
	.num_regs	= 1,
	.ledctrl_base	= 54,
};

static const struct platform_device_id mc13xxx_led_id_table[] = {
	{ "mc13783-led", (kernel_ulong_t)&mc13783_led_devtype, },
	{ "mc13892-led", (kernel_ulong_t)&mc13892_led_devtype, },
	{ "mc34708-led", (kernel_ulong_t)&mc34708_led_devtype, },
	{ }
};
MODULE_DEVICE_TABLE(platform, mc13xxx_led_id_table);

static struct platform_driver mc13xxx_led_driver = {
	.driver	= {
		.name	= "mc13xxx-led",
	},
	.remove		= mc13xxx_led_remove,
	.id_table	= mc13xxx_led_id_table,
};
module_platform_driver_probe(mc13xxx_led_driver, mc13xxx_led_probe);

MODULE_DESCRIPTION("LEDs driver for Freescale MC13XXX PMIC");
MODULE_AUTHOR("Philippe Retornaz <philippe.retornaz@epfl.ch>");
MODULE_LICENSE("GPL");
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