| Message ID | 536C873E.8060408@xs4all.nl (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 09 May 2014 09:43:58 +0200 Hans Verkuil <hverkuil@xs4all.nl> wrote: > Andrew, can you merge this for 3.15 or 3.16 (you decide)? While it fixes a sparse error > for the media subsystem, it is not really appropriate to go through our media tree. > > Thanks, > > Hans > > > When running sparse over drivers/media/v4l2-core/v4l2-ioctl.c I get these > errors: > > drivers/media/v4l2-core/v4l2-ioctl.c:2043:9: error: bad integer constant expression > drivers/media/v4l2-core/v4l2-ioctl.c:2044:9: error: bad integer constant expression > drivers/media/v4l2-core/v4l2-ioctl.c:2045:9: error: bad integer constant expression > drivers/media/v4l2-core/v4l2-ioctl.c:2046:9: error: bad integer constant expression > > etc. > > The root cause of that turns out to be in include/asm-generic/ioctl.h: > > #include <uapi/asm-generic/ioctl.h> > > /* provoke compile error for invalid uses of size argument */ > extern unsigned int __invalid_size_argument_for_IOC; > #define _IOC_TYPECHECK(t) \ > ((sizeof(t) == sizeof(t[1]) && \ > sizeof(t) < (1 << _IOC_SIZEBITS)) ? \ > sizeof(t) : __invalid_size_argument_for_IOC) > > If it is defined as this (as is already done if __KERNEL__ is not defined): > > #define _IOC_TYPECHECK(t) (sizeof(t)) > > then all is well with the world. > > This patch allows sparse to work correctly. > > --- a/include/asm-generic/ioctl.h > +++ b/include/asm-generic/ioctl.h > @@ -3,10 +3,15 @@ > > #include <uapi/asm-generic/ioctl.h> > > +#ifdef __CHECKER__ > +#define _IOC_TYPECHECK(t) (sizeof(t)) > +#else > /* provoke compile error for invalid uses of size argument */ > extern unsigned int __invalid_size_argument_for_IOC; > #define _IOC_TYPECHECK(t) \ > ((sizeof(t) == sizeof(t[1]) && \ > sizeof(t) < (1 << _IOC_SIZEBITS)) ? \ > sizeof(t) : __invalid_size_argument_for_IOC) > +#endif > + > #endif /* _ASM_GENERIC_IOCTL_H */ Can't we use BUILD_BUG_ON() here? That's neater, more standard and BUILD_BUG_ON() already has sparse handling. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 05/09/2014 10:59 PM, Andrew Morton wrote: > On Fri, 09 May 2014 09:43:58 +0200 Hans Verkuil <hverkuil@xs4all.nl> wrote: > >> Andrew, can you merge this for 3.15 or 3.16 (you decide)? While it fixes a sparse error >> for the media subsystem, it is not really appropriate to go through our media tree. >> >> Thanks, >> >> Hans >> >> >> When running sparse over drivers/media/v4l2-core/v4l2-ioctl.c I get these >> errors: >> >> drivers/media/v4l2-core/v4l2-ioctl.c:2043:9: error: bad integer constant expression >> drivers/media/v4l2-core/v4l2-ioctl.c:2044:9: error: bad integer constant expression >> drivers/media/v4l2-core/v4l2-ioctl.c:2045:9: error: bad integer constant expression >> drivers/media/v4l2-core/v4l2-ioctl.c:2046:9: error: bad integer constant expression >> >> etc. >> >> The root cause of that turns out to be in include/asm-generic/ioctl.h: >> >> #include <uapi/asm-generic/ioctl.h> >> >> /* provoke compile error for invalid uses of size argument */ >> extern unsigned int __invalid_size_argument_for_IOC; >> #define _IOC_TYPECHECK(t) \ >> ((sizeof(t) == sizeof(t[1]) && \ >> sizeof(t) < (1 << _IOC_SIZEBITS)) ? \ >> sizeof(t) : __invalid_size_argument_for_IOC) >> >> If it is defined as this (as is already done if __KERNEL__ is not defined): >> >> #define _IOC_TYPECHECK(t) (sizeof(t)) >> >> then all is well with the world. >> >> This patch allows sparse to work correctly. >> >> --- a/include/asm-generic/ioctl.h >> +++ b/include/asm-generic/ioctl.h >> @@ -3,10 +3,15 @@ >> >> #include <uapi/asm-generic/ioctl.h> >> >> +#ifdef __CHECKER__ >> +#define _IOC_TYPECHECK(t) (sizeof(t)) >> +#else >> /* provoke compile error for invalid uses of size argument */ >> extern unsigned int __invalid_size_argument_for_IOC; >> #define _IOC_TYPECHECK(t) \ >> ((sizeof(t) == sizeof(t[1]) && \ >> sizeof(t) < (1 << _IOC_SIZEBITS)) ? \ >> sizeof(t) : __invalid_size_argument_for_IOC) >> +#endif >> + >> #endif /* _ASM_GENERIC_IOCTL_H */ > > Can't we use BUILD_BUG_ON() here? That's neater, more standard and > BUILD_BUG_ON() already has sparse handling. I don't think so. BUILD_BUG_ON is not meant to be used in an expression, whereas _IOC_TYPECHECK(t) is (it should return sizeof(t)). This looked promising at first sight: #define _IOC_TYPECHECK(t) \ ({BUILD_BUG_ON(sizeof(t) == sizeof(t[1]) && sizeof(t) < (1 << _IOC_SIZEBITS)); \ sizeof(t);}) But it leads to 'case label does not reduce to an integer constant' compile errors. And a typical ioctl define expands to this horror: case (((2U) << (((0 +8)+8)+14)) | ((('M')) << (0 +8)) | (((1)) << 0) | (((({do { bool __cond = !(!(sizeof(int) == sizeof(int[1]) && sizeof(int) < (1 << 14))); extern void __compiletime_assert_1909(void) __attribute__((error("BUILD_BUG_ON failed: " "sizeof(int) == sizeof(int[1]) && sizeof(int) < (1 << _IOC_SIZEBITS)"))); if (__cond) __compiletime_assert_1909(); do { } while (0); } while (0); sizeof(int);}))) << ((0 +8)+8))): which also explains the errors: case labels with function calls in them won't compile. So I think my proposed patch is the best approach. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/asm-generic/ioctl.h b/include/asm-generic/ioctl.h index d17295b..297fb0d 100644 --- a/include/asm-generic/ioctl.h +++ b/include/asm-generic/ioctl.h @@ -3,10 +3,15 @@ #include <uapi/asm-generic/ioctl.h> +#ifdef __CHECKER__ +#define _IOC_TYPECHECK(t) (sizeof(t)) +#else /* provoke compile error for invalid uses of size argument */ extern unsigned int __invalid_size_argument_for_IOC; #define _IOC_TYPECHECK(t) \ ((sizeof(t) == sizeof(t[1]) && \ sizeof(t) < (1 << _IOC_SIZEBITS)) ? \ sizeof(t) : __invalid_size_argument_for_IOC) +#endif + #endif /* _ASM_GENERIC_IOCTL_H */
Andrew, can you merge this for 3.15 or 3.16 (you decide)? While it fixes a sparse error for the media subsystem, it is not really appropriate to go through our media tree. Thanks, Hans When running sparse over drivers/media/v4l2-core/v4l2-ioctl.c I get these errors: drivers/media/v4l2-core/v4l2-ioctl.c:2043:9: error: bad integer constant expression drivers/media/v4l2-core/v4l2-ioctl.c:2044:9: error: bad integer constant expression drivers/media/v4l2-core/v4l2-ioctl.c:2045:9: error: bad integer constant expression drivers/media/v4l2-core/v4l2-ioctl.c:2046:9: error: bad integer constant expression etc. The root cause of that turns out to be in include/asm-generic/ioctl.h: #include <uapi/asm-generic/ioctl.h> /* provoke compile error for invalid uses of size argument */ extern unsigned int __invalid_size_argument_for_IOC; #define _IOC_TYPECHECK(t) \ ((sizeof(t) == sizeof(t[1]) && \ sizeof(t) < (1 << _IOC_SIZEBITS)) ? \ sizeof(t) : __invalid_size_argument_for_IOC) If it is defined as this (as is already done if __KERNEL__ is not defined): #define _IOC_TYPECHECK(t) (sizeof(t)) then all is well with the world. This patch allows sparse to work correctly. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> --- include/asm-generic/ioctl.h | 5 +++++ 1 file changed, 5 insertions(+)