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Subject[PATCH] Make asm-generic/ioctl.h more generic using conditionals.

Allow individual architectures to override a small set of macros
before including asm-generic/ioctl.h, in order to greatly simplify a
number of existing ioctl.h files.

The overrideable macros would be:

_IOC_SIZEBITS
_IOC_DIRBITS
_IOC_NONE
_IOC_WRITE
_IOC_READ

---

i've submitted this once before, and it didn't seem to garner a lot
of attention one way or the other. this patch can be applied
standalone and shouldn't affect anything, but it would subsequently
allow at least a few ioctl.h files to be shortened considerably.

diff --git a/include/asm-generic/ioctl.h b/include/asm-generic/ioctl.h
index cd02729..4fb087a 100644
--- a/include/asm-generic/ioctl.h
+++ b/include/asm-generic/ioctl.h
@@ -21,8 +21,19 @@
*/
#define _IOC_NRBITS 8
#define _IOC_TYPEBITS 8
-#define _IOC_SIZEBITS 14
-#define _IOC_DIRBITS 2
+
+/*
+ * Let any architecture override either of the following before
+ * including this file.
+ */
+
+#ifndef _IOC_SIZEBITS
+# define _IOC_SIZEBITS 14
+#endif
+
+#ifndef _IOC_DIRBITS
+# define _IOC_DIRBITS 2
+#endif

#define _IOC_NRMASK ((1 << _IOC_NRBITS)-1)
#define _IOC_TYPEMASK ((1 << _IOC_TYPEBITS)-1)
@@ -35,11 +46,21 @@
#define _IOC_DIRSHIFT (_IOC_SIZESHIFT+_IOC_SIZEBITS)

/*
- * Direction bits.
+ * Direction bits, which any architecture can choose to override
+ * before including this file.
*/
-#define _IOC_NONE 0U
-#define _IOC_WRITE 1U
-#define _IOC_READ 2U
+
+#ifndef _IOC_NONE
+# define _IOC_NONE 0U
+#endif
+
+#ifndef _IOC_WRITE
+# define _IOC_WRITE 1U
+#endif
+
+#ifndef _IOC_READ
+# define _IOC_READ 2U
+#endif

#define _IOC(dir,type,nr,size) \
(((dir) << _IOC_DIRSHIFT) | \
--
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA
http://fsdev.net/wiki/index.php?title=Main_Page
========================================================================
-
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