linux/sound/core/pcm_memory.c
Takashi Iwai d4cfb30fce ALSA: pcm: Set per-card upper limit of PCM buffer allocations
Currently, the available buffer allocation size for a PCM stream
depends on the preallocated size; when a buffer has been preallocated,
the max buffer size is set to that size, so that application won't
re-allocate too much memory.  OTOH, when no preallocation is done,
each substream may allocate arbitrary size of buffers as long as
snd_pcm_hardware.buffer_bytes_max allows -- which can be quite high,
HD-audio sets 1GB there.

It means that the system may consume a high amount of pages for PCM
buffers, and they are pinned and never swapped out.  This can lead to
OOM easily.

For avoiding such a situation, this patch adds the upper limit per
card.  Each snd_pcm_lib_malloc_pages() and _free_pages() calls are
tracked and it will return an error if the total amount of buffers
goes over the defined upper limit.  The default value is set to 32MB,
which should be really large enough for usual operations.

If larger buffers are needed for any specific usage, it can be
adjusted (also dynamically) via snd_pcm.max_alloc_per_card option.
Setting zero there means no chceck is performed, and again, unlimited
amount of buffers are allowed.

Link: https://lore.kernel.org/r/20200120124423.11862-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2020-01-21 07:11:55 +01:00

507 lines
15 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Digital Audio (PCM) abstract layer
* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
*/
#include <linux/io.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/moduleparam.h>
#include <linux/vmalloc.h>
#include <linux/export.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/info.h>
#include <sound/initval.h>
#include "pcm_local.h"
static int preallocate_dma = 1;
module_param(preallocate_dma, int, 0444);
MODULE_PARM_DESC(preallocate_dma, "Preallocate DMA memory when the PCM devices are initialized.");
static int maximum_substreams = 4;
module_param(maximum_substreams, int, 0444);
MODULE_PARM_DESC(maximum_substreams, "Maximum substreams with preallocated DMA memory.");
static const size_t snd_minimum_buffer = 16384;
static unsigned long max_alloc_per_card = 32UL * 1024UL * 1024UL;
module_param(max_alloc_per_card, ulong, 0644);
MODULE_PARM_DESC(max_alloc_per_card, "Max total allocation bytes per card.");
static int do_alloc_pages(struct snd_card *card, int type, struct device *dev,
size_t size, struct snd_dma_buffer *dmab)
{
int err;
if (max_alloc_per_card &&
card->total_pcm_alloc_bytes + size > max_alloc_per_card)
return -ENOMEM;
err = snd_dma_alloc_pages(type, dev, size, dmab);
if (!err) {
mutex_lock(&card->memory_mutex);
card->total_pcm_alloc_bytes += dmab->bytes;
mutex_unlock(&card->memory_mutex);
}
return err;
}
static void do_free_pages(struct snd_card *card, struct snd_dma_buffer *dmab)
{
if (!dmab->area)
return;
mutex_lock(&card->memory_mutex);
WARN_ON(card->total_pcm_alloc_bytes < dmab->bytes);
card->total_pcm_alloc_bytes -= dmab->bytes;
mutex_unlock(&card->memory_mutex);
snd_dma_free_pages(dmab);
dmab->area = NULL;
}
/*
* try to allocate as the large pages as possible.
* stores the resultant memory size in *res_size.
*
* the minimum size is snd_minimum_buffer. it should be power of 2.
*/
static int preallocate_pcm_pages(struct snd_pcm_substream *substream, size_t size)
{
struct snd_dma_buffer *dmab = &substream->dma_buffer;
struct snd_card *card = substream->pcm->card;
size_t orig_size = size;
int err;
do {
err = do_alloc_pages(card, dmab->dev.type, dmab->dev.dev,
size, dmab);
if (err != -ENOMEM)
return err;
size >>= 1;
} while (size >= snd_minimum_buffer);
dmab->bytes = 0; /* tell error */
pr_warn("ALSA pcmC%dD%d%c,%d:%s: cannot preallocate for size %zu\n",
substream->pcm->card->number, substream->pcm->device,
substream->stream ? 'c' : 'p', substream->number,
substream->pcm->name, orig_size);
return 0;
}
/*
* release the preallocated buffer if not yet done.
*/
static void snd_pcm_lib_preallocate_dma_free(struct snd_pcm_substream *substream)
{
do_free_pages(substream->pcm->card, &substream->dma_buffer);
}
/**
* snd_pcm_lib_preallocate_free - release the preallocated buffer of the specified substream.
* @substream: the pcm substream instance
*
* Releases the pre-allocated buffer of the given substream.
*/
void snd_pcm_lib_preallocate_free(struct snd_pcm_substream *substream)
{
snd_pcm_lib_preallocate_dma_free(substream);
}
/**
* snd_pcm_lib_preallocate_free_for_all - release all pre-allocated buffers on the pcm
* @pcm: the pcm instance
*
* Releases all the pre-allocated buffers on the given pcm.
*/
void snd_pcm_lib_preallocate_free_for_all(struct snd_pcm *pcm)
{
struct snd_pcm_substream *substream;
int stream;
for (stream = 0; stream < 2; stream++)
for (substream = pcm->streams[stream].substream; substream; substream = substream->next)
snd_pcm_lib_preallocate_free(substream);
}
EXPORT_SYMBOL(snd_pcm_lib_preallocate_free_for_all);
#ifdef CONFIG_SND_VERBOSE_PROCFS
/*
* read callback for prealloc proc file
*
* prints the current allocated size in kB.
*/
static void snd_pcm_lib_preallocate_proc_read(struct snd_info_entry *entry,
struct snd_info_buffer *buffer)
{
struct snd_pcm_substream *substream = entry->private_data;
snd_iprintf(buffer, "%lu\n", (unsigned long) substream->dma_buffer.bytes / 1024);
}
/*
* read callback for prealloc_max proc file
*
* prints the maximum allowed size in kB.
*/
static void snd_pcm_lib_preallocate_max_proc_read(struct snd_info_entry *entry,
struct snd_info_buffer *buffer)
{
struct snd_pcm_substream *substream = entry->private_data;
snd_iprintf(buffer, "%lu\n", (unsigned long) substream->dma_max / 1024);
}
/*
* write callback for prealloc proc file
*
* accepts the preallocation size in kB.
*/
static void snd_pcm_lib_preallocate_proc_write(struct snd_info_entry *entry,
struct snd_info_buffer *buffer)
{
struct snd_pcm_substream *substream = entry->private_data;
struct snd_card *card = substream->pcm->card;
char line[64], str[64];
size_t size;
struct snd_dma_buffer new_dmab;
if (substream->runtime) {
buffer->error = -EBUSY;
return;
}
if (!snd_info_get_line(buffer, line, sizeof(line))) {
snd_info_get_str(str, line, sizeof(str));
size = simple_strtoul(str, NULL, 10) * 1024;
if ((size != 0 && size < 8192) || size > substream->dma_max) {
buffer->error = -EINVAL;
return;
}
if (substream->dma_buffer.bytes == size)
return;
memset(&new_dmab, 0, sizeof(new_dmab));
new_dmab.dev = substream->dma_buffer.dev;
if (size > 0) {
if (do_alloc_pages(card,
substream->dma_buffer.dev.type,
substream->dma_buffer.dev.dev,
size, &new_dmab) < 0) {
buffer->error = -ENOMEM;
return;
}
substream->buffer_bytes_max = size;
} else {
substream->buffer_bytes_max = UINT_MAX;
}
if (substream->dma_buffer.area)
do_free_pages(card, &substream->dma_buffer);
substream->dma_buffer = new_dmab;
} else {
buffer->error = -EINVAL;
}
}
static inline void preallocate_info_init(struct snd_pcm_substream *substream)
{
struct snd_info_entry *entry;
entry = snd_info_create_card_entry(substream->pcm->card, "prealloc",
substream->proc_root);
if (entry) {
snd_info_set_text_ops(entry, substream,
snd_pcm_lib_preallocate_proc_read);
entry->c.text.write = snd_pcm_lib_preallocate_proc_write;
entry->mode |= 0200;
}
entry = snd_info_create_card_entry(substream->pcm->card, "prealloc_max",
substream->proc_root);
if (entry)
snd_info_set_text_ops(entry, substream,
snd_pcm_lib_preallocate_max_proc_read);
}
#else /* !CONFIG_SND_VERBOSE_PROCFS */
#define preallocate_info_init(s)
#endif /* CONFIG_SND_VERBOSE_PROCFS */
/*
* pre-allocate the buffer and create a proc file for the substream
*/
static void preallocate_pages(struct snd_pcm_substream *substream,
int type, struct device *data,
size_t size, size_t max, bool managed)
{
if (snd_BUG_ON(substream->dma_buffer.dev.type))
return;
substream->dma_buffer.dev.type = type;
substream->dma_buffer.dev.dev = data;
if (size > 0 && preallocate_dma && substream->number < maximum_substreams)
preallocate_pcm_pages(substream, size);
if (substream->dma_buffer.bytes > 0)
substream->buffer_bytes_max = substream->dma_buffer.bytes;
substream->dma_max = max;
if (max > 0)
preallocate_info_init(substream);
if (managed)
substream->managed_buffer_alloc = 1;
}
static void preallocate_pages_for_all(struct snd_pcm *pcm, int type,
void *data, size_t size, size_t max,
bool managed)
{
struct snd_pcm_substream *substream;
int stream;
for (stream = 0; stream < 2; stream++)
for (substream = pcm->streams[stream].substream; substream;
substream = substream->next)
preallocate_pages(substream, type, data, size, max,
managed);
}
/**
* snd_pcm_lib_preallocate_pages - pre-allocation for the given DMA type
* @substream: the pcm substream instance
* @type: DMA type (SNDRV_DMA_TYPE_*)
* @data: DMA type dependent data
* @size: the requested pre-allocation size in bytes
* @max: the max. allowed pre-allocation size
*
* Do pre-allocation for the given DMA buffer type.
*/
void snd_pcm_lib_preallocate_pages(struct snd_pcm_substream *substream,
int type, struct device *data,
size_t size, size_t max)
{
preallocate_pages(substream, type, data, size, max, false);
}
EXPORT_SYMBOL(snd_pcm_lib_preallocate_pages);
/**
* snd_pcm_lib_preallocate_pages_for_all - pre-allocation for continuous memory type (all substreams)
* @pcm: the pcm instance
* @type: DMA type (SNDRV_DMA_TYPE_*)
* @data: DMA type dependent data
* @size: the requested pre-allocation size in bytes
* @max: the max. allowed pre-allocation size
*
* Do pre-allocation to all substreams of the given pcm for the
* specified DMA type.
*/
void snd_pcm_lib_preallocate_pages_for_all(struct snd_pcm *pcm,
int type, void *data,
size_t size, size_t max)
{
preallocate_pages_for_all(pcm, type, data, size, max, false);
}
EXPORT_SYMBOL(snd_pcm_lib_preallocate_pages_for_all);
/**
* snd_pcm_set_managed_buffer - set up buffer management for a substream
* @substream: the pcm substream instance
* @type: DMA type (SNDRV_DMA_TYPE_*)
* @data: DMA type dependent data
* @size: the requested pre-allocation size in bytes
* @max: the max. allowed pre-allocation size
*
* Do pre-allocation for the given DMA buffer type, and set the managed
* buffer allocation mode to the given substream.
* In this mode, PCM core will allocate a buffer automatically before PCM
* hw_params ops call, and release the buffer after PCM hw_free ops call
* as well, so that the driver doesn't need to invoke the allocation and
* the release explicitly in its callback.
* When a buffer is actually allocated before the PCM hw_params call, it
* turns on the runtime buffer_changed flag for drivers changing their h/w
* parameters accordingly.
*/
void snd_pcm_set_managed_buffer(struct snd_pcm_substream *substream, int type,
struct device *data, size_t size, size_t max)
{
preallocate_pages(substream, type, data, size, max, true);
}
EXPORT_SYMBOL(snd_pcm_set_managed_buffer);
/**
* snd_pcm_set_managed_buffer_all - set up buffer management for all substreams
* for all substreams
* @pcm: the pcm instance
* @type: DMA type (SNDRV_DMA_TYPE_*)
* @data: DMA type dependent data
* @size: the requested pre-allocation size in bytes
* @max: the max. allowed pre-allocation size
*
* Do pre-allocation to all substreams of the given pcm for the specified DMA
* type and size, and set the managed_buffer_alloc flag to each substream.
*/
void snd_pcm_set_managed_buffer_all(struct snd_pcm *pcm, int type,
struct device *data,
size_t size, size_t max)
{
preallocate_pages_for_all(pcm, type, data, size, max, true);
}
EXPORT_SYMBOL(snd_pcm_set_managed_buffer_all);
#ifdef CONFIG_SND_DMA_SGBUF
/*
* snd_pcm_sgbuf_ops_page - get the page struct at the given offset
* @substream: the pcm substream instance
* @offset: the buffer offset
*
* Used as the page callback of PCM ops.
*
* Return: The page struct at the given buffer offset. %NULL on failure.
*/
struct page *snd_pcm_sgbuf_ops_page(struct snd_pcm_substream *substream, unsigned long offset)
{
struct snd_sg_buf *sgbuf = snd_pcm_substream_sgbuf(substream);
unsigned int idx = offset >> PAGE_SHIFT;
if (idx >= (unsigned int)sgbuf->pages)
return NULL;
return sgbuf->page_table[idx];
}
#endif /* CONFIG_SND_DMA_SGBUF */
/**
* snd_pcm_lib_malloc_pages - allocate the DMA buffer
* @substream: the substream to allocate the DMA buffer to
* @size: the requested buffer size in bytes
*
* Allocates the DMA buffer on the BUS type given earlier to
* snd_pcm_lib_preallocate_xxx_pages().
*
* Return: 1 if the buffer is changed, 0 if not changed, or a negative
* code on failure.
*/
int snd_pcm_lib_malloc_pages(struct snd_pcm_substream *substream, size_t size)
{
struct snd_card *card = substream->pcm->card;
struct snd_pcm_runtime *runtime;
struct snd_dma_buffer *dmab = NULL;
if (PCM_RUNTIME_CHECK(substream))
return -EINVAL;
if (snd_BUG_ON(substream->dma_buffer.dev.type ==
SNDRV_DMA_TYPE_UNKNOWN))
return -EINVAL;
runtime = substream->runtime;
if (runtime->dma_buffer_p) {
/* perphaps, we might free the large DMA memory region
to save some space here, but the actual solution
costs us less time */
if (runtime->dma_buffer_p->bytes >= size) {
runtime->dma_bytes = size;
return 0; /* ok, do not change */
}
snd_pcm_lib_free_pages(substream);
}
if (substream->dma_buffer.area != NULL &&
substream->dma_buffer.bytes >= size) {
dmab = &substream->dma_buffer; /* use the pre-allocated buffer */
} else {
dmab = kzalloc(sizeof(*dmab), GFP_KERNEL);
if (! dmab)
return -ENOMEM;
dmab->dev = substream->dma_buffer.dev;
if (do_alloc_pages(card,
substream->dma_buffer.dev.type,
substream->dma_buffer.dev.dev,
size, dmab) < 0) {
kfree(dmab);
return -ENOMEM;
}
}
snd_pcm_set_runtime_buffer(substream, dmab);
runtime->dma_bytes = size;
return 1; /* area was changed */
}
EXPORT_SYMBOL(snd_pcm_lib_malloc_pages);
/**
* snd_pcm_lib_free_pages - release the allocated DMA buffer.
* @substream: the substream to release the DMA buffer
*
* Releases the DMA buffer allocated via snd_pcm_lib_malloc_pages().
*
* Return: Zero if successful, or a negative error code on failure.
*/
int snd_pcm_lib_free_pages(struct snd_pcm_substream *substream)
{
struct snd_card *card = substream->pcm->card;
struct snd_pcm_runtime *runtime;
if (PCM_RUNTIME_CHECK(substream))
return -EINVAL;
runtime = substream->runtime;
if (runtime->dma_area == NULL)
return 0;
if (runtime->dma_buffer_p != &substream->dma_buffer) {
/* it's a newly allocated buffer. release it now. */
do_free_pages(card, runtime->dma_buffer_p);
kfree(runtime->dma_buffer_p);
}
snd_pcm_set_runtime_buffer(substream, NULL);
return 0;
}
EXPORT_SYMBOL(snd_pcm_lib_free_pages);
int _snd_pcm_lib_alloc_vmalloc_buffer(struct snd_pcm_substream *substream,
size_t size, gfp_t gfp_flags)
{
struct snd_pcm_runtime *runtime;
if (PCM_RUNTIME_CHECK(substream))
return -EINVAL;
runtime = substream->runtime;
if (runtime->dma_area) {
if (runtime->dma_bytes >= size)
return 0; /* already large enough */
vfree(runtime->dma_area);
}
runtime->dma_area = __vmalloc(size, gfp_flags, PAGE_KERNEL);
if (!runtime->dma_area)
return -ENOMEM;
runtime->dma_bytes = size;
return 1;
}
EXPORT_SYMBOL(_snd_pcm_lib_alloc_vmalloc_buffer);
/**
* snd_pcm_lib_free_vmalloc_buffer - free vmalloc buffer
* @substream: the substream with a buffer allocated by
* snd_pcm_lib_alloc_vmalloc_buffer()
*
* Return: Zero if successful, or a negative error code on failure.
*/
int snd_pcm_lib_free_vmalloc_buffer(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime;
if (PCM_RUNTIME_CHECK(substream))
return -EINVAL;
runtime = substream->runtime;
vfree(runtime->dma_area);
runtime->dma_area = NULL;
return 0;
}
EXPORT_SYMBOL(snd_pcm_lib_free_vmalloc_buffer);
/**
* snd_pcm_lib_get_vmalloc_page - map vmalloc buffer offset to page struct
* @substream: the substream with a buffer allocated by
* snd_pcm_lib_alloc_vmalloc_buffer()
* @offset: offset in the buffer
*
* This function is to be used as the page callback in the PCM ops.
*
* Return: The page struct, or %NULL on failure.
*/
struct page *snd_pcm_lib_get_vmalloc_page(struct snd_pcm_substream *substream,
unsigned long offset)
{
return vmalloc_to_page(substream->runtime->dma_area + offset);
}
EXPORT_SYMBOL(snd_pcm_lib_get_vmalloc_page);