At Thu, 30 Jun 2011 13:43:33 +0100,
Ralf Baechle wrote:
>
> On Thu, Jun 30, 2011 at 02:38:20PM +0200, Takashi Iwai wrote:
>
> > > In userland an empty definition will be used for _IOC_TYPECHECK so there
> > > won't be an error. So userland already is already using the existing
> > > value for SNDRV_SB_CSP_IOCTL_LOAD_CODE ...
> >
> > Right. It has an invalid direction (3), but apps won't care such
> > details anyway.
> >
> > > With a crude hack like
> > >
> > > #define SNDRV_SB_CSP_IOCTL_LOAD_CODE \
> > > _IOC(_IOC_WRITE,'H', 0x11, sizeof(struct snd_sb_csp_microcode))
> > >
> > > error checking can be bypassed and all will be fine as long as the
> > > resulting value doesn't result in in a a duplicate case value - which it
> > > doesn't, at least not in my testing.
> > >
> > > Should work but isn't nice.
> >
> > Indeed. But which is uglier is hard to answer :)
> >
> > If you are fine with the hacked ioctl number above, I can put it
> > with some comments. This won't break anything, at least.
>
> Go ahead then and yes, this really deserves a comment.
OK, here is the patch.
Takashi
===
From: Takashi Iwai <tiwai@xxxxxxx>
Subject: [PATCH] ALSA: sb16 - Fix build errors on MIPS and others with 13bit
ioctl size
One of ioctl definition in sound/sb16_csp.h contains the data size
over 8kB, and this causes build errors on architectures like MIPS,
which define _IOC_SIZEBITS=13.
For avoiding this build errors but keeping the compatibility, manually
exapnd with _IOC() instead of using _IOW() for the problematic ioctl.
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
include/sound/sb16_csp.h | 9 ++++++++-
1 files changed, 8 insertions(+), 1 deletions(-)
diff --git a/include/sound/sb16_csp.h b/include/sound/sb16_csp.h
index 736eac7..af1b49e 100644
--- a/include/sound/sb16_csp.h
+++ b/include/sound/sb16_csp.h
@@ -99,7 +99,14 @@ struct snd_sb_csp_info {
/* get CSP information */
#define SNDRV_SB_CSP_IOCTL_INFO _IOR('H', 0x10, struct snd_sb_csp_info)
/* load microcode to CSP */
-#define SNDRV_SB_CSP_IOCTL_LOAD_CODE _IOW('H', 0x11, struct snd_sb_csp_microcode)
+/* NOTE: struct snd_sb_csp_microcode overflows the max size (13 bits)
+ * defined for some architectures like MIPS, and it leads to build errors.
+ * (x86 and co have 14-bit size, thus it's valid, though.)
+ * As a workaround for skipping the size-limit check, here we don't use the
+ * normal _IOW() macro but _IOC() with the manual argument.
+ */
+#define SNDRV_SB_CSP_IOCTL_LOAD_CODE \
+ _IOC(_IOC_WRITE, 'H', 0x11, sizeof(struct snd_sb_csp_microcode))
/* unload microcode from CSP */
#define SNDRV_SB_CSP_IOCTL_UNLOAD_CODE _IO('H', 0x12)
/* start CSP */
--
1.7.6
