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@suse.de 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@suse.de --- 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 */