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Subject[PATCH] Fix _IOC_TYPECHECK sparse error
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>

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 */


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