[alsa-devel] Applied "ASoC: pcm: Sync delayed work before releasing resources" to the asoc tree

[Mark Brown]

The patch

   ASoC: pcm: Sync delayed work before releasing resources

has been applied to the asoc tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 5d61f0ba6524dcbad198126e5793157c8afdea91 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai at suse.de>
Date: Fri, 25 Aug 2017 12:04:07 +0200
Subject: [PATCH] ASoC: pcm: Sync delayed work before releasing resources

When ASoC driver is unbound dynamically during its operation (i.e. a
kind of hot-unplug), we may hit Oops due to the resource access after
the release by a delayed work, something like:

  Unable to handle kernel paging request at virtual address dead000000000220
  ....
  PC is at soc_dapm_dai_stream_event.isra.14+0x20/0xd0
  LR is at snd_soc_dapm_stream_event+0x74/0xa8
  ....
  [<ffff000008715610>] soc_dapm_dai_stream_event.isra.14+0x20/0xd0
  [<ffff00000871989c>] snd_soc_dapm_stream_event+0x74/0xa8
  [<ffff00000871b23c>] close_delayed_work+0x3c/0x50
  [<ffff0000080bbd6c>] process_one_work+0x1ac/0x318
  [<ffff0000080bbf20>] worker_thread+0x48/0x420
  [<ffff0000080c201c>] kthread+0xfc/0x128
  [<ffff0000080842f0>] ret_from_fork+0x10/0x18

For fixing the race, this patch adds a sync-point in pcm private_free
callback to finish the delayed work before actually releasing the
resources.

Reported-by: Hiep Cao Minh <cm-hiep at jinso.co.jp>
Reported-by: Kuninori Morimoto <kuninori.morimoto.gx at renesas.com>
Tested-by: Kuninori Morimoto <kuninori.morimoto.gx at renesas.com>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
Signed-off-by: Mark Brown <broonie at kernel.org>
---
 sound/soc/soc-pcm.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 94b88b897c3b..c0f0b09cb433 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -2632,6 +2632,17 @@ static int dpcm_fe_dai_close(struct snd_pcm_substream *fe_substream)
 	return ret;
 }
 
+static void soc_pcm_private_free(struct snd_pcm *pcm)
+{
+	struct snd_soc_pcm_runtime *rtd = pcm->private_data;
+	struct snd_soc_platform *platform = rtd->platform;
+
+	/* need to sync the delayed work before releasing resources */
+	flush_delayed_work(&rtd->delayed_work);
+	if (platform->driver->pcm_free)
+		platform->driver->pcm_free(pcm);
+}
+
 /* create a new pcm */
 int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
 {
@@ -2757,7 +2768,7 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
 		}
 	}
 
-	pcm->private_free = platform->driver->pcm_free;
+	pcm->private_free = soc_pcm_private_free;
 out:
 	dev_info(rtd->card->dev, "%s <-> %s mapping ok\n",
 		 (rtd->num_codecs > 1) ? "multicodec" : rtd->codec_dai->name,
-- 
2.14.1