[PATCH 3.12 030/142] ALSA: compress: Disable GET_CODEC_CAPS ioctl for some architectures

From: Jiri Slaby
Date: Wed Feb 24 2016 - 06:13:27 EST

From: Takashi Iwai <tiwai@xxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.


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@xxxxxxxxxx>
Acked-by: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
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 dac296a7faad..3f2b4b7f2ec9 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
/* TODO:
* - add substream support for multiple devices in case of
* SND_DYNAMIC_MINORS is not used
@@ -439,6 +446,7 @@ out:
return retval;

static int
snd_compr_get_codec_caps(struct snd_compr_stream *stream, unsigned long arg)
@@ -462,6 +470,7 @@ out:
return retval;

/* revisit this with snd_pcm_preallocate_xxx */
static int snd_compr_allocate_buffer(struct snd_compr_stream *stream,
@@ -803,9 +812,11 @@ static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
retval = snd_compr_get_caps(stream, arg);
retval = snd_compr_get_codec_caps(stream, arg);
retval = snd_compr_set_params(stream, arg);