diff options
Diffstat (limited to 'sound/core/pcm_native.c')
| -rw-r--r-- | sound/core/pcm_native.c | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index d35c6614fdab..9ade0c8b54a3 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -3376,10 +3376,29 @@ static int snd_pcm_mmap_control(struct snd_pcm_substream *substream, struct file area->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; return 0; } + +static bool pcm_status_mmap_allowed(struct snd_pcm_file *pcm_file) +{ + if (pcm_file->no_compat_mmap) + return false; + /* Disallow the status/control mmap when SYNC_APPLPTR flag is set; + * it enforces the user-space to fall back to snd_pcm_sync_ptr(), + * thus it effectively assures the manual update of appl_ptr. + * In theory, it should be enough to disallow only PCM control mmap, + * but since the current alsa-lib implementation requires both status + * and control mmaps always paired, we have to disable both of them. + */ + if (pcm_file->substream->runtime->hw.info & SNDRV_PCM_INFO_SYNC_APPLPTR) + return false; + return true; +} + #else /* ! coherent mmap */ /* * don't support mmap for status and control records. */ +#define pcm_status_mmap_allowed(pcm_file) false + static int snd_pcm_mmap_status(struct snd_pcm_substream *substream, struct file *file, struct vm_area_struct *area) { @@ -3563,11 +3582,11 @@ static int snd_pcm_mmap(struct file *file, struct vm_area_struct *area) offset = area->vm_pgoff << PAGE_SHIFT; switch (offset) { case SNDRV_PCM_MMAP_OFFSET_STATUS: - if (pcm_file->no_compat_mmap) + if (!pcm_status_mmap_allowed(pcm_file)) return -ENXIO; return snd_pcm_mmap_status(substream, file, area); case SNDRV_PCM_MMAP_OFFSET_CONTROL: - if (pcm_file->no_compat_mmap) + if (!pcm_status_mmap_allowed(pcm_file)) return -ENXIO; return snd_pcm_mmap_control(substream, file, area); default: |