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.
Signed-off-by: Takashi Iwai tiwai@suse.de --- include/sound/pcm.h | 3 ++ sound/core/pcm_lib.c | 111 ++++++++++++++++++++++++---------------- sound/core/pcm_native.c | 2 +- 3 files changed, 71 insertions(+), 45 deletions(-)
diff --git a/include/sound/pcm.h b/include/sound/pcm.h index 19f564606ac4..ff4a0c1c93a2 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -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); diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 9c121a921b04..3303914c58ea 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -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); diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 95fc56e403b1..34efd4d198d6 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -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)