Staging
v0.8.1
https://github.com/torvalds/linux
Revision bc1c116974a5c3f498112a6f175d3e4a8cd5bdbc authored by Jens Axboe on 08 June 2006, 06:49:06 UTC, committed by Linus Torvalds on 08 June 2006, 22:14:23 UTC
There's a race between shutting down one io scheduler and firing up the
next, in which a new io could enter and cause the io scheduler to be
invoked with bad or NULL data.

To fix this, we need to maintain the queue lock for a bit longer.
Unfortunately we cannot do that, since the elevator init requires to be
run without the lock held.  This isn't easily fixable, without also
changing the mempool API.  So split the initialization into two parts,
and alloc-init operation and an attach operation.  Then we can
preallocate the io scheduler and related structures, and run the attach
inside the lock after we detach the old one.

This patch has survived 30 minutes of 1 second io scheduler switching
with a very busy io load.

Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent 26e780e
Raw File
Tip revision: bc1c116974a5c3f498112a6f175d3e4a8cd5bdbc authored by Jens Axboe on 08 June 2006, 06:49:06 UTC
[PATCH] elevator switching race
Tip revision: bc1c116
beep.c
/*
 * Beep using pcm
 *
 * Copyright (c) by Takashi Iwai <tiwai@suse.de>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <sound/driver.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/pci.h>
#include <linux/dma-mapping.h>
#include <sound/core.h>
#include <sound/control.h>
#include "pmac.h"

struct pmac_beep {
	int running;		/* boolean */
	int volume;		/* mixer volume: 0-100 */
	int volume_play;	/* currently playing volume */
	int hz;
	int nsamples;
	short *buf;		/* allocated wave buffer */
	dma_addr_t addr;	/* physical address of buffer */
	struct input_dev *dev;
};

/*
 * stop beep if running
 */
void snd_pmac_beep_stop(struct snd_pmac *chip)
{
	struct pmac_beep *beep = chip->beep;
	if (beep && beep->running) {
		beep->running = 0;
		snd_pmac_beep_dma_stop(chip);
	}
}

/*
 * Stuff for outputting a beep.  The values range from -327 to +327
 * so we can multiply by an amplitude in the range 0..100 to get a
 * signed short value to put in the output buffer.
 */
static short beep_wform[256] = {
	0,	40,	79,	117,	153,	187,	218,	245,
	269,	288,	304,	316,	323,	327,	327,	324,
	318,	310,	299,	288,	275,	262,	249,	236,
	224,	213,	204,	196,	190,	186,	183,	182,
	182,	183,	186,	189,	192,	196,	200,	203,
	206,	208,	209,	209,	209,	207,	204,	201,
	197,	193,	188,	183,	179,	174,	170,	166,
	163,	161,	160,	159,	159,	160,	161,	162,
	164,	166,	168,	169,	171,	171,	171,	170,
	169,	167,	163,	159,	155,	150,	144,	139,
	133,	128,	122,	117,	113,	110,	107,	105,
	103,	103,	103,	103,	104,	104,	105,	105,
	105,	103,	101,	97,	92,	86,	78,	68,
	58,	45,	32,	18,	3,	-11,	-26,	-41,
	-55,	-68,	-79,	-88,	-95,	-100,	-102,	-102,
	-99,	-93,	-85,	-75,	-62,	-48,	-33,	-16,
	0,	16,	33,	48,	62,	75,	85,	93,
	99,	102,	102,	100,	95,	88,	79,	68,
	55,	41,	26,	11,	-3,	-18,	-32,	-45,
	-58,	-68,	-78,	-86,	-92,	-97,	-101,	-103,
	-105,	-105,	-105,	-104,	-104,	-103,	-103,	-103,
	-103,	-105,	-107,	-110,	-113,	-117,	-122,	-128,
	-133,	-139,	-144,	-150,	-155,	-159,	-163,	-167,
	-169,	-170,	-171,	-171,	-171,	-169,	-168,	-166,
	-164,	-162,	-161,	-160,	-159,	-159,	-160,	-161,
	-163,	-166,	-170,	-174,	-179,	-183,	-188,	-193,
	-197,	-201,	-204,	-207,	-209,	-209,	-209,	-208,
	-206,	-203,	-200,	-196,	-192,	-189,	-186,	-183,
	-182,	-182,	-183,	-186,	-190,	-196,	-204,	-213,
	-224,	-236,	-249,	-262,	-275,	-288,	-299,	-310,
	-318,	-324,	-327,	-327,	-323,	-316,	-304,	-288,
	-269,	-245,	-218,	-187,	-153,	-117,	-79,	-40,
};

#define BEEP_SRATE	22050	/* 22050 Hz sample rate */
#define BEEP_BUFLEN	512
#define BEEP_VOLUME	15	/* 0 - 100 */

static int snd_pmac_beep_event(struct input_dev *dev, unsigned int type,
			       unsigned int code, int hz)
{
	struct snd_pmac *chip;
	struct pmac_beep *beep;
	unsigned long flags;
	int beep_speed = 0;
	int srate;
	int period, ncycles, nsamples;
	int i, j, f;
	short *p;

	if (type != EV_SND)
		return -1;

	switch (code) {
	case SND_BELL: if (hz) hz = 1000;
	case SND_TONE: break;
	default: return -1;
	}

	chip = dev->private;
	if (! chip || (beep = chip->beep) == NULL)
		return -1;

	if (! hz) {
		spin_lock_irqsave(&chip->reg_lock, flags);
		if (beep->running)
			snd_pmac_beep_stop(chip);
		spin_unlock_irqrestore(&chip->reg_lock, flags);
		return 0;
	}

	beep_speed = snd_pmac_rate_index(chip, &chip->playback, BEEP_SRATE);
	srate = chip->freq_table[beep_speed];

	if (hz <= srate / BEEP_BUFLEN || hz > srate / 2)
		hz = 1000;

	spin_lock_irqsave(&chip->reg_lock, flags);
	if (chip->playback.running || chip->capture.running || beep->running) {
		spin_unlock_irqrestore(&chip->reg_lock, flags);
		return 0;
	}
	beep->running = 1;
	spin_unlock_irqrestore(&chip->reg_lock, flags);

	if (hz == beep->hz && beep->volume == beep->volume_play) {
		nsamples = beep->nsamples;
	} else {
		period = srate * 256 / hz;	/* fixed point */
		ncycles = BEEP_BUFLEN * 256 / period;
		nsamples = (period * ncycles) >> 8;
		f = ncycles * 65536 / nsamples;
		j = 0;
		p = beep->buf;
		for (i = 0; i < nsamples; ++i, p += 2) {
			p[0] = p[1] = beep_wform[j >> 8] * beep->volume;
			j = (j + f) & 0xffff;
		}
		beep->hz = hz;
		beep->volume_play = beep->volume;
		beep->nsamples = nsamples;
	}

	spin_lock_irqsave(&chip->reg_lock, flags);
	snd_pmac_beep_dma_start(chip, beep->nsamples * 4, beep->addr, beep_speed);
	spin_unlock_irqrestore(&chip->reg_lock, flags);
	return 0;
}

/*
 * beep volume mixer
 */

static int snd_pmac_info_beep(struct snd_kcontrol *kcontrol,
			      struct snd_ctl_elem_info *uinfo)
{
	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
	uinfo->count = 1;
	uinfo->value.integer.min = 0;
	uinfo->value.integer.max = 100;
	return 0;
}

static int snd_pmac_get_beep(struct snd_kcontrol *kcontrol,
			     struct snd_ctl_elem_value *ucontrol)
{
	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
	snd_assert(chip->beep, return -ENXIO);
	ucontrol->value.integer.value[0] = chip->beep->volume;
	return 0;
}

static int snd_pmac_put_beep(struct snd_kcontrol *kcontrol,
			     struct snd_ctl_elem_value *ucontrol)
{
	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
	int oval;
	snd_assert(chip->beep, return -ENXIO);
	oval = chip->beep->volume;
	chip->beep->volume = ucontrol->value.integer.value[0];
	return oval != chip->beep->volume;
}

static struct snd_kcontrol_new snd_pmac_beep_mixer = {
	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
	.name = "Beep Playback Volume",
	.info = snd_pmac_info_beep,
	.get = snd_pmac_get_beep,
	.put = snd_pmac_put_beep,
};

/* Initialize beep stuff */
int __init snd_pmac_attach_beep(struct snd_pmac *chip)
{
	struct pmac_beep *beep;
	struct input_dev *input_dev;
	void *dmabuf;
	int err = -ENOMEM;

	beep = kzalloc(sizeof(*beep), GFP_KERNEL);
	dmabuf = dma_alloc_coherent(&chip->pdev->dev, BEEP_BUFLEN * 4,
				    &beep->addr, GFP_KERNEL);
	input_dev = input_allocate_device();
	if (!beep || !dmabuf || !input_dev)
		goto fail;

	/* FIXME: set more better values */
	input_dev->name = "PowerMac Beep";
	input_dev->phys = "powermac/beep";
	input_dev->id.bustype = BUS_ADB;
	input_dev->id.vendor = 0x001f;
	input_dev->id.product = 0x0001;
	input_dev->id.version = 0x0100;

	input_dev->evbit[0] = BIT(EV_SND);
	input_dev->sndbit[0] = BIT(SND_BELL) | BIT(SND_TONE);
	input_dev->event = snd_pmac_beep_event;
	input_dev->private = chip;
	input_dev->cdev.dev = &chip->pdev->dev;

	beep->dev = input_dev;
	beep->buf = dmabuf;
	beep->volume = BEEP_VOLUME;
	beep->running = 0;

	err = snd_ctl_add(chip->card, snd_ctl_new1(&snd_pmac_beep_mixer, chip));
	if (err < 0)
		goto fail;

	chip->beep = beep;
	input_register_device(beep->dev);

	return 0;

 fail:	input_free_device(input_dev);
	kfree(dmabuf);
	kfree(beep);
	return err;
}

void snd_pmac_detach_beep(struct snd_pmac *chip)
{
	if (chip->beep) {
		input_unregister_device(chip->beep->dev);
		dma_free_coherent(&chip->pdev->dev, BEEP_BUFLEN * 4,
				  chip->beep->buf, chip->beep->addr);
		kfree(chip->beep);
		chip->beep = NULL;
	}
}
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