/*
 * mtk-afe-platform-driver.c  --  Mediatek afe platform driver
 *
 * Copyright (c) 2016 MediaTek Inc.
 * Author: Garlic Tseng <garlic.tseng@mediatek.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 and
 * only version 2 as published by the Free Software Foundation.
 *
 * 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.
 */

#include <linux/module.h>
#include <linux/dma-mapping.h>
#include <sound/soc.h>

#include "mtk-afe-platform-driver.h"
#include "mtk-base-afe.h"

static snd_pcm_uframes_t mtk_afe_pcm_pointer
			 (struct snd_pcm_substream *substream)
{
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	struct mtk_base_afe *afe = snd_soc_platform_get_drvdata(rtd->platform);
	struct mtk_base_afe_memif *memif = &afe->memif[rtd->cpu_dai->id];
	const struct mtk_base_memif_data *memif_data = memif->data;
	struct regmap *regmap = afe->regmap;
	struct device *dev = afe->dev;
	int reg_ofs_base = memif_data->reg_ofs_base;
	int reg_ofs_cur = memif_data->reg_ofs_cur;
	unsigned int hw_ptr = 0, hw_base = 0;
	int ret, pcm_ptr_bytes;

	ret = regmap_read(regmap, reg_ofs_cur, &hw_ptr);
	if (ret || hw_ptr == 0) {
		dev_err(dev, "%s hw_ptr err\n", __func__);
		pcm_ptr_bytes = 0;
		goto POINTER_RETURN_FRAMES;
	}

	ret = regmap_read(regmap, reg_ofs_base, &hw_base);
	if (ret || hw_base == 0) {
		dev_err(dev, "%s hw_ptr err\n", __func__);
		pcm_ptr_bytes = 0;
		goto POINTER_RETURN_FRAMES;
	}

	pcm_ptr_bytes = hw_ptr - hw_base;

POINTER_RETURN_FRAMES:
	return bytes_to_frames(substream->runtime, pcm_ptr_bytes);
}

static const struct snd_pcm_ops mtk_afe_pcm_ops = {
	.ioctl = snd_pcm_lib_ioctl,
	.pointer = mtk_afe_pcm_pointer,
};

static int mtk_afe_pcm_new(struct snd_soc_pcm_runtime *rtd)
{
	size_t size;
	struct snd_card *card = rtd->card->snd_card;
	struct snd_pcm *pcm = rtd->pcm;
	struct mtk_base_afe *afe = snd_soc_platform_get_drvdata(rtd->platform);

	size = afe->mtk_afe_hardware->buffer_bytes_max;
	return snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,
						     card->dev, size, size);
}

static void mtk_afe_pcm_free(struct snd_pcm *pcm)
{
	snd_pcm_lib_preallocate_free_for_all(pcm);
}

const struct snd_soc_platform_driver mtk_afe_pcm_platform = {
	.ops = &mtk_afe_pcm_ops,
	.pcm_new = mtk_afe_pcm_new,
	.pcm_free = mtk_afe_pcm_free,
};
EXPORT_SYMBOL_GPL(mtk_afe_pcm_platform);

MODULE_DESCRIPTION("Mediatek simple platform driver");
MODULE_AUTHOR("Garlic Tseng <garlic.tseng@mediatek.com>");
MODULE_LICENSE("GPL v2");

>
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/commit/?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/sound?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>sound</a>/<a href='/cgit.cgi/linux/net-next.git/commit/sound/aoa?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>aoa</a>/<a href='/cgit.cgi/linux/net-next.git/commit/sound/aoa/codecs?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>codecs</a>/<a href='/cgit.cgi/linux/net-next.git/commit/sound/aoa/codecs/toonie.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>toonie.c</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='h' value='nds-private-remove'/><input type='hidden' name='id' value='966d2b04e070bc040319aaebfec09e0144dc3341'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;</td><td class='right'>2017-01-28 06:42:20 -0600</td></tr>
<tr><th>committer</th><td>Tejun Heo &lt;tj@kernel.org&gt;</td><td class='right'>2017-01-28 07:49:42 -0500</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/sound/aoa/codecs/toonie.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/sound/aoa/codecs/toonie.c?id=966d2b04e070bc040319aaebfec09e0144dc3341'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>4b96156e3d1dd4dfd6039b7c219c9dc4616da52d</a> /<a href='/cgit.cgi/linux/net-next.git/tree/sound/aoa/codecs/toonie.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>sound/aoa/codecs/toonie.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/sound/aoa/codecs/toonie.c?h=nds-private-remove&amp;id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/sound/aoa/codecs/toonie.c?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341&amp;id2=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>diff</a>)</td></tr></table>
<div class='commit-subject'>percpu-refcount: fix reference leak during percpu-atomic transition</div><div class='commit-msg'>percpu_ref_tryget() and percpu_ref_tryget_live() should return
"true" IFF they acquire a reference. But the return value from
atomic_long_inc_not_zero() is a long and may have high bits set,
e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines
is bool so the reference may actually be acquired but the routines
return "false" which results in a reference leak since the caller
assumes it does not need to do a corresponding percpu_ref_put().

This was seen when performing CPU hotplug during I/O, as hangs in
blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start)
raced with percpu_ref_tryget (blk_mq_timeout_work).
Sample stack trace:

__switch_to+0x2c0/0x450
__schedule+0x2f8/0x970
schedule+0x48/0xc0
blk_mq_freeze_queue_wait+0x94/0x120
blk_mq_queue_reinit_work+0xb8/0x180
blk_mq_queue_reinit_prepare+0x84/0xa0
cpuhp_invoke_callback+0x17c/0x600
cpuhp_up_callbacks+0x58/0x150
_cpu_up+0xf0/0x1c0
do_cpu_up+0x120/0x150
cpu_subsys_online+0x64/0xe0
device_online+0xb4/0x120
online_store+0xb4/0xc0
dev_attr_store+0x68/0xa0
sysfs_kf_write+0x80/0xb0
kernfs_fop_write+0x17c/0x250
__vfs_write+0x6c/0x1e0
vfs_write+0xd0/0x270
SyS_write+0x6c/0x110
system_call+0x38/0xe0

Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS,
and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests.
However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0
and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set.

The fix is to make the tryget routines use an actual boolean internally instead
of the atomic long result truncated to a int.

Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints
Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751
Signed-off-by: Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;
Reviewed-by: Jens Axboe &lt;axboe@fb.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints")
Cc: stable@vger.kernel.org # v3.18+
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>Diffstat</a> (limited to 'sound/aoa/codecs/toonie.c')</div><table summary='diffstat' class='diffstat'>