clear-pkgs-linux-iot-lts2018/0245-ALSA-pcm-conditionally-avoid-mmap-of-control-data.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Date: Thu, 16 Jun 2016 16:01:00 +0530
Subject: [PATCH] ALSA: pcm: conditionally avoid mmap of control data.

In case of mmap, by default alsa-lib mmaps both control and status data.

If driver subscribes for application pointer update, driver needs to get
notification whenever appl ptr changes. With the above case driver won't
get appl ptr notifications.

This patch check on a hw info flag and returns error when user land asks
for mmaping control & status data, thus forcing user to issue
IOCTL_SYNC_PTR.

Change-Id: I05b83f630812face322c474d9bbb6d56cbdc08fb
Suggested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Ramesh Babu <ramesh.babu@intel.com>
Signed-off-by: Jaikrishna Nemallapudi <jaikrishnax.nemallapudi@intel.com>
Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty@intel.com>
Signed-off-by: Mallikarjun, chippalkatti <mallikarjunx.chippalkatti@intel.com>
Reviewed-on:
Reviewed-by: audio_build
Reviewed-by: Sm, Bhadur A <bhadur.a.sm@intel.com>
Tested-by: Sm, Bhadur A <bhadur.a.sm@intel.com>
---
 include/uapi/sound/asound.h |  1 +
 sound/core/pcm_native.c     | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index ff57e4c89de4..9120cce11265 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -296,6 +296,7 @@ typedef int __bitwise snd_pcm_subformat_t;
 #define SNDRV_PCM_INFO_HAS_LINK_ABSOLUTE_ATIME     0x02000000  /* report absolute hardware link audio time, not reset on startup */
 #define SNDRV_PCM_INFO_HAS_LINK_ESTIMATED_ATIME    0x04000000  /* report estimated link audio time */
 #define SNDRV_PCM_INFO_HAS_LINK_SYNCHRONIZED_ATIME 0x08000000  /* report synchronized audio/system time */
+#define SNDRV_PCM_INFO_NO_STATUS_MMAP	0x10000000	/* status and control mmap not supported */
 
 #define SNDRV_PCM_INFO_DRAIN_TRIGGER	0x40000000		/* internal kernel flag - trigger in drain */
 #define SNDRV_PCM_INFO_FIFO_IN_FRAMES	0x80000000	/* internal kernel flag - FIFO size is in frames */
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 56ab147c8429..98beb1c08e24 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -3491,21 +3491,38 @@ static int snd_pcm_mmap(struct file *file, struct vm_area_struct *area)
 	struct snd_pcm_file * pcm_file;
 	struct snd_pcm_substream *substream;	
 	unsigned long offset;
+	unsigned int info;
 	
 	pcm_file = file->private_data;
 	substream = pcm_file->substream;
 	if (PCM_RUNTIME_CHECK(substream))
 		return -ENXIO;
+	info = substream->runtime->hw.info;
 
 	offset = area->vm_pgoff << PAGE_SHIFT;
 	switch (offset) {
 	case SNDRV_PCM_MMAP_OFFSET_STATUS:
 		if (!pcm_status_mmap_allowed(pcm_file))
 			return -ENXIO;
+		/*
+		 * force fallback to ioctl if driver doesn't support status
+		 * and control mmap.
+		 */
+		if (info & SNDRV_PCM_INFO_NO_STATUS_MMAP)
+			return -ENXIO;
+
 		return snd_pcm_mmap_status(substream, file, area);
 	case SNDRV_PCM_MMAP_OFFSET_CONTROL:
 		if (!pcm_control_mmap_allowed(pcm_file))
 			return -ENXIO;
+
+		/*
+		 * force fallback to ioctl if driver doesn't support status
+		 * and control mmap.
+		 */
+		if (info & SNDRV_PCM_INFO_NO_STATUS_MMAP)
+			return -ENXIO;
+
 		return snd_pcm_mmap_control(substream, file, area);
 	default:
 		return snd_pcm_mmap_data(substream, file, area);
-- 
https://clearlinux.org