[3.16.y-ckt stable] Patch "ALSA: compress: Disable GET_CODEC_CAPS ioctl for some architectures" has been added to the 3.16.y-ckt tree

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ALSA: compress: Disable GET_CODEC_CAPS ioctl for some architectures

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt25.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

---8<------------------------------------------------------------

>From 22c5fcbfb6cccb24388b91f56233b8a2bdefb100 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai at suse.de>
Date: Mon, 25 Jan 2016 13:59:21 +0100
Subject: ALSA: compress: Disable GET_CODEC_CAPS ioctl for some architectures

commit 462b3f161beb62eeb290f4ec52f5ead29a2f8ac7 upstream.

Some architectures like PowerPC can handle the maximum struct size in
an ioctl only up to 13 bits, and struct snd_compr_codec_caps used by
SNDRV_COMPRESS_GET_CODEC_CAPS ioctl overflows this limit.  This
problem was revealed recently by a powerpc change, as it's now treated
as a fatal build error.

This patch is a stop-gap for that: for architectures with less than 14
bit ioctl struct size, get rid of the handling of the relevant ioctl.
We should provide an alternative equivalent ioctl code later, but for
now just paper over it.  Luckily, the compress API hasn't been used on
such architectures, so the impact must be effectively zero.

Reviewed-by: Mark Brown <broonie at kernel.org>
Acked-by: Sudip Mukherjee <sudipm.mukherjee at gmail.com>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 sound/core/compress_offload.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index 7403f348ed14..91525fafe73b 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -44,6 +44,13 @@
 #include <sound/compress_offload.h>
 #include <sound/compress_driver.h>

+/* struct snd_compr_codec_caps overflows the ioctl bit size for some
+ * architectures, so we need to disable the relevant ioctls.
+ */
+#if _IOC_SIZEBITS < 14
+#define COMPR_CODEC_CAPS_OVERFLOW
+#endif
+
 /* TODO:
  * - add substream support for multiple devices in case of
  *	SND_DYNAMIC_MINORS is not used
@@ -438,6 +445,7 @@ out:
 	return retval;
 }

+#ifndef COMPR_CODEC_CAPS_OVERFLOW
 static int
 snd_compr_get_codec_caps(struct snd_compr_stream *stream, unsigned long arg)
 {
@@ -461,6 +469,7 @@ out:
 	kfree(caps);
 	return retval;
 }
+#endif /* !COMPR_CODEC_CAPS_OVERFLOW */

 /* revisit this with snd_pcm_preallocate_xxx */
 static int snd_compr_allocate_buffer(struct snd_compr_stream *stream,
@@ -799,9 +808,11 @@ static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
 	case _IOC_NR(SNDRV_COMPRESS_GET_CAPS):
 		retval = snd_compr_get_caps(stream, arg);
 		break;
+#ifndef COMPR_CODEC_CAPS_OVERFLOW
 	case _IOC_NR(SNDRV_COMPRESS_GET_CODEC_CAPS):
 		retval = snd_compr_get_codec_caps(stream, arg);
 		break;
+#endif
 	case _IOC_NR(SNDRV_COMPRESS_SET_PARAMS):
 		retval = snd_compr_set_params(stream, arg);
 		break;