ALSA: pcm: Disable only control mmap for explicit appl_ptr sync

[mirror_ubuntu-artful-kernel.git] / sound / core / pcm_native.c

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 1c53d93e68f298a352cee0cc1fb505477d7edd4b..0d18343105313b5db8afbf48d44bd52705693025 100644 (file)
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -3388,12 +3388,23 @@ 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;
+       /* See pcm_control_mmap_allowed() below.
+        * Since older alsa-lib requires both status and control mmaps to be
+        * coupled, we have to disable the status mmap for old alsa-lib, too.
+        */
+       if (pcm_file->user_pversion < SNDRV_PROTOCOL_VERSION(2, 0, 14) &&
+           (pcm_file->substream->runtime->hw.info & SNDRV_PCM_INFO_SYNC_APPLPTR))
+               return false;
+       return true;
+}
+
+static bool pcm_control_mmap_allowed(struct snd_pcm_file *pcm_file)
+{
+       if (pcm_file->no_compat_mmap)
+               return false;
+       /* Disallow the 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;
@@ -3405,6 +3416,7 @@ static bool pcm_status_mmap_allowed(struct snd_pcm_file *pcm_file)
  * don't support mmap for status and control records.
  */
 #define pcm_status_mmap_allowed(pcm_file)      false
+#define pcm_control_mmap_allowed(pcm_file)     false
 
 static int snd_pcm_mmap_status(struct snd_pcm_substream *substream, struct file *file,
                               struct vm_area_struct *area)
@@ -3593,7 +3605,7 @@ static int snd_pcm_mmap(struct file *file, struct vm_area_struct *area)
                        return -ENXIO;
                return snd_pcm_mmap_status(substream, file, area);
        case SNDRV_PCM_MMAP_OFFSET_CONTROL:
-               if (!pcm_status_mmap_allowed(pcm_file))
+               if (!pcm_control_mmap_allowed(pcm_file))
                        return -ENXIO;
                return snd_pcm_mmap_control(substream, file, area);
        default: