ALSA: compress: add support for 32bit calls in a 64bit kernel

BugLink: https://bugs.launchpad.net/bugs/1826212

commit c1036889 upstream.

Compress offload does not support ioctl calls from a 32bit userspace
in a 64 bit kernel. This patch adds support for ioctls from a 32bit
userspace in a 64bit kernel
Signed-off-by: Ravindra Lokhande <rlokhande@nvidia.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

sound/core/compress_offload.c

@@ -38,6 +38,7 @@
 #include <linux/uio.h>
 #include <linux/uaccess.h>
 #include <linux/module.h>
+#include <linux/compat.h>
 #include <sound/core.h>
 #include <sound/initval.h>
 #include <sound/compress_params.h>
@@ -859,6 +860,15 @@ static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
 	return retval;
 }
 
+/* support of 32bit userspace on 64bit platforms */
+#ifdef CONFIG_COMPAT
+static long snd_compr_ioctl_compat(struct file *file, unsigned int cmd,
+						unsigned long arg)
+{
+	return snd_compr_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
+}
+#endif
+
 static const struct file_operations snd_compr_file_ops = {
 		.owner =	THIS_MODULE,
 		.open =		snd_compr_open,
@@ -866,6 +876,9 @@ static const struct file_operations snd_compr_file_ops = {
 		.write =	snd_compr_write,
 		.read =		snd_compr_read,
 		.unlocked_ioctl = snd_compr_ioctl,
+#ifdef CONFIG_COMPAT
+		.compat_ioctl = snd_compr_ioctl_compat,
+#endif
 		.mmap =		snd_compr_mmap,
 		.poll =		snd_compr_poll,
 };