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ALSA: pcm: Add copy ops with iov_iter 

iov_iter is a universal interface to copy the data chunk from/to
user-space and kernel in a unified manner.  This API can fit for ALSA
PCM copy ops, too; we had to split to copy_user and copy_kernel in the
past, and those can be unified to a single ops with iov_iter.

This patch adds a new PCM copy ops that passes iov_iter for copying
both kernel and user-space in the same way.  This patch touches only
the ALSA PCM core part, and the actual users will be replaced in the
following patches.

The expansion of iov_iter is done in the PCM core right before calling
each copy callback.  It's a bit suboptimal, but I took this now as
it's the most straightforward replacement.  The more conversion to
iov_iter in the caller side is a TODO for future.

As of now, the old copy_user and copy_kernel ops are still kept.
Once after all users are converted, we'll drop the old copy_user and
copy_kernel ops, too.

Link: https://lore.kernel.org/r/20230815190136.8987-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2023-08-15 21:01:13 +02:00
parent 70e969eb23
commit cf393babb3
3 changed files with 71 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/sound/pcm.h
View File

@ -16,6 +16,7 @@
#include <linux/bitops.h>
#include <linux/pm_qos.h>
#include <linux/refcount.h>
#include <linux/uio.h>
#define snd_pcm_substream_chip(substream) ((substream)->private_data)
#define snd_pcm_chip(pcm) ((pcm)->private_data)
@ -68,6 +69,8 @@ struct snd_pcm_ops {
struct snd_pcm_audio_tstamp_report *audio_tstamp_report);
int (*fill_silence)(struct snd_pcm_substream *substream, int channel,
unsigned long pos, unsigned long bytes);
int (*copy)(struct snd_pcm_substream *substream, int channel,
unsigned long pos, struct iov_iter *iter, unsigned long bytes);
int (*copy_user)(struct snd_pcm_substream *substream, int channel,
unsigned long pos, void __user *buf,
unsigned long bytes);

111
sound/core/pcm_lib.c
View File

@ -1973,10 +1973,11 @@ static int wait_for_avail(struct snd_pcm_substream *substream,
typedef int (*pcm_transfer_f)(struct snd_pcm_substream *substream,
int channel, unsigned long hwoff,
void *buf, unsigned long bytes);
struct iov_iter *iter, unsigned long bytes);
typedef int (*pcm_copy_f)(struct snd_pcm_substream *, snd_pcm_uframes_t, void *,
snd_pcm_uframes_t, snd_pcm_uframes_t, pcm_transfer_f);
snd_pcm_uframes_t, snd_pcm_uframes_t, pcm_transfer_f,
bool);
/* calculate the target DMA-buffer position to be written/read */
static void *get_dma_ptr(struct snd_pcm_runtime *runtime,
@ -1986,32 +1987,24 @@ static void *get_dma_ptr(struct snd_pcm_runtime *runtime,
channel * (runtime->dma_bytes / runtime->channels);
}
/* default copy_user ops for write; used for both interleaved and non- modes */
/* default copy ops for write; used for both interleaved and non- modes */
static int default_write_copy(struct snd_pcm_substream *substream,
int channel, unsigned long hwoff,
void *buf, unsigned long bytes)
struct iov_iter *iter, unsigned long bytes)
{
if (copy_from_user(get_dma_ptr(substream->runtime, channel, hwoff),
(void __user *)buf, bytes))
if (!copy_from_iter(get_dma_ptr(substream->runtime, channel, hwoff),
bytes, iter))
return -EFAULT;
return 0;
}
/* default copy_kernel ops for write */
static int default_write_copy_kernel(struct snd_pcm_substream *substream,
int channel, unsigned long hwoff,
void *buf, unsigned long bytes)
{
memcpy(get_dma_ptr(substream->runtime, channel, hwoff), buf, bytes);
return 0;
}
/* fill silence instead of copy data; called as a transfer helper
* from __snd_pcm_lib_write() or directly from noninterleaved_copy() when
* a NULL buffer is passed
*/
static int fill_silence(struct snd_pcm_substream *substream, int channel,
unsigned long hwoff, void *buf, unsigned long bytes)
unsigned long hwoff, struct iov_iter *iter,
unsigned long bytes)
{
struct snd_pcm_runtime *runtime = substream->runtime;
@ -2027,25 +2020,54 @@ static int fill_silence(struct snd_pcm_substream *substream, int channel,
return 0;
}
/* default copy_user ops for read; used for both interleaved and non- modes */
/* default copy ops for read; used for both interleaved and non- modes */
static int default_read_copy(struct snd_pcm_substream *substream,
int channel, unsigned long hwoff,
void *buf, unsigned long bytes)
struct iov_iter *iter, unsigned long bytes)
{
if (copy_to_user((void __user *)buf,
get_dma_ptr(substream->runtime, channel, hwoff),
bytes))
if (!copy_to_iter(get_dma_ptr(substream->runtime, channel, hwoff),
bytes, iter))
return -EFAULT;
return 0;
}
/* default copy_kernel ops for read */
static int default_read_copy_kernel(struct snd_pcm_substream *substream,
int channel, unsigned long hwoff,
void *buf, unsigned long bytes)
/* a wrapper for calling old copy_kernel or copy_user ops */
static int call_old_copy(struct snd_pcm_substream *substream,
int channel, unsigned long hwoff,
struct iov_iter *iter, unsigned long bytes)
{
memcpy(buf, get_dma_ptr(substream->runtime, channel, hwoff), bytes);
return 0;
if (iov_iter_is_kvec(iter))
return substream->ops->copy_kernel(substream, channel, hwoff,
iter_iov_addr(iter), bytes);
else
return substream->ops->copy_user(substream, channel, hwoff,
iter_iov_addr(iter), bytes);
}
/* call transfer with the filled iov_iter */
static int do_transfer(struct snd_pcm_substream *substream, int c,
unsigned long hwoff, void *data, unsigned long bytes,
pcm_transfer_f transfer, bool in_kernel)
{
struct iov_iter iter;
int err, type;
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
type = ITER_SOURCE;
else
type = ITER_DEST;
if (in_kernel) {
struct kvec kvec = { data, bytes };
iov_iter_kvec(&iter, type, &kvec, 1, bytes);
return transfer(substream, c, hwoff, &iter, bytes);
}
err = import_ubuf(type, (__force void __user *)data, bytes, &iter);
if (err)
return err;
return transfer(substream, c, hwoff, &iter, bytes);
}
/* call transfer function with the converted pointers and sizes;
@ -2055,7 +2077,8 @@ static int interleaved_copy(struct snd_pcm_substream *substream,
snd_pcm_uframes_t hwoff, void *data,
snd_pcm_uframes_t off,
snd_pcm_uframes_t frames,
pcm_transfer_f transfer)
pcm_transfer_f transfer,
bool in_kernel)
{
struct snd_pcm_runtime *runtime = substream->runtime;
@ -2063,7 +2086,9 @@ static int interleaved_copy(struct snd_pcm_substream *substream,
hwoff = frames_to_bytes(runtime, hwoff);
off = frames_to_bytes(runtime, off);
frames = frames_to_bytes(runtime, frames);
return transfer(substream, 0, hwoff, data + off, frames);
return do_transfer(substream, 0, hwoff, data + off, frames, transfer,
in_kernel);
}
/* call transfer function with the converted pointers and sizes for each
@ -2073,7 +2098,8 @@ static int noninterleaved_copy(struct snd_pcm_substream *substream,
snd_pcm_uframes_t hwoff, void *data,
snd_pcm_uframes_t off,
snd_pcm_uframes_t frames,
pcm_transfer_f transfer)
pcm_transfer_f transfer,
bool in_kernel)
{
struct snd_pcm_runtime *runtime = substream->runtime;
int channels = runtime->channels;
@ -2091,8 +2117,8 @@ static int noninterleaved_copy(struct snd_pcm_substream *substream,
if (!data || !*bufs)
err = fill_silence(substream, c, hwoff, NULL, frames);
else
err = transfer(substream, c, hwoff, *bufs + off,
frames);
err = do_transfer(substream, c, hwoff, *bufs + off,
frames, transfer, in_kernel);
if (err < 0)
return err;
}
@ -2108,10 +2134,10 @@ static int fill_silence_frames(struct snd_pcm_substream *substream,
if (substream->runtime->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED ||
substream->runtime->access == SNDRV_PCM_ACCESS_MMAP_INTERLEAVED)
return interleaved_copy(substream, off, NULL, 0, frames,
fill_silence);
fill_silence, true);
else
return noninterleaved_copy(substream, off, NULL, 0, frames,
fill_silence);
fill_silence, true);
}
/* sanity-check for read/write methods */
@ -2121,7 +2147,7 @@ static int pcm_sanity_check(struct snd_pcm_substream *substream)
if (PCM_RUNTIME_CHECK(substream))
return -ENXIO;
runtime = substream->runtime;
if (snd_BUG_ON(!substream->ops->copy_user && !runtime->dma_area))
if (snd_BUG_ON(!substream->ops->copy && !substream->ops->copy_user && !runtime->dma_area))
return -EINVAL;
if (runtime->state == SNDRV_PCM_STATE_OPEN)
return -EBADFD;
@ -2226,15 +2252,12 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream,
transfer = fill_silence;
else
return -EINVAL;
} else if (in_kernel) {
if (substream->ops->copy_kernel)
transfer = substream->ops->copy_kernel;
else
transfer = is_playback ?
default_write_copy_kernel : default_read_copy_kernel;
} else {
if (substream->ops->copy_user)
transfer = (pcm_transfer_f)substream->ops->copy_user;
if (substream->ops->copy)
transfer = substream->ops->copy;
else if ((in_kernel && substream->ops->copy_kernel) ||
(!in_kernel && substream->ops->copy_user))
transfer = call_old_copy;
else
transfer = is_playback ?
default_write_copy : default_read_copy;
@ -2307,7 +2330,7 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream,
if (!is_playback)
snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_CPU);
err = writer(substream, appl_ofs, data, offset, frames,
transfer);
transfer, in_kernel);
if (is_playback)
snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_DEVICE);
snd_pcm_stream_lock_irq(substream);

2
sound/core/pcm_native.c
View File

@ -809,7 +809,7 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
runtime->boundary *= 2;
/* clear the buffer for avoiding possible kernel info leaks */
if (runtime->dma_area && !substream->ops->copy_user) {
if (runtime->dma_area && !substream->ops->copy && !substream->ops->copy_user) {
size_t size = runtime->dma_bytes;
if (runtime->info & SNDRV_PCM_INFO_MMAP)