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const vs. __attribute__((const)) confusion

PATCH Nikita Danilov 1 participant 1 message Jan 20, 2004 1 message not in the archive USB

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Nikita Danilov

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Quoted 4 lines · Linux Kernel Mailing List

ChangeSet 1.1490.3.216, 2004/01/19 10:43:54-08:00, [email protected]

[PATCH] const vs. __attribute__((const)) confusion

Quoted 8 lines

From: "H. Peter Anvin" <[email protected]>

Declaring a function to return a const scalar value is pretty meaningless. These functions are really trying to say that they don't alter any external state.

Fix that up by using __attribute__((const)), if the compiler supports that.

Let's then also replace all existing usages of __attribute__((const)) with __attribute_const__, while we are here.

I don't have the hardware to test this patch, but at least it compiles.

Nikita.
===== arch/ia64/kernel/unwind.c 1.35 vs edited =====

arch/ia64/kernel/unwind.c +1 -1
@@ -650,7 +650,7 @@
 
 /* Unwind decoder routines */
 
-static enum unw_register_index __attribute__((const))
+static enum unw_register_index __attribute_const__
 decode_abreg (unsigned char abreg, int memory)
 {
 	switch (abreg) {

===== drivers/usb/class/audio.c 1.42 vs edited =====

drivers/usb/class/audio.c +2 -2
@@ -203,12 +203,12 @@
 
 #define AUDIO_DEBUG 1
 
-#define SND_DEV_DSP16   5 
+#define SND_DEV_DSP16   5
 
 #define dprintk(x)
 
 #undef abs
-extern int abs(int __x) __attribute__ ((__const__)); /* Shut up warning */
+extern int abs(int __x) __attribute_const__; /* Shut up warning */
 
 /* --------------------------------------------------------------------- */

===== include/asm-alpha/byteorder.h 1.2 vs edited =====

include/asm-alpha/byteorder.h +1 -1
@@ -6,7 +6,7 @@
 
 #ifdef __GNUC__
 
-static __inline __u32 __attribute__((__const)) __arch__swab32(__u32 x)
+static __inline __u32 __attribute_const__ __arch__swab32(__u32 x)
 {
 	/*
 	 * Unfortunately, we can't use the 6 instruction sequence

===== include/asm-arm/current.h 1.3 vs edited =====

include/asm-arm/current.h +1 -1
@@ -3,7 +3,7 @@
 
 #include <linux/thread_info.h>
 
-static inline struct task_struct *get_current(void) __attribute__ (( __const__ ));
+static inline struct task_struct *get_current(void) __attribute_const__;
 
 static inline struct task_struct *get_current(void)
 {

===== include/asm-arm/thread_info.h 1.8 vs edited =====

include/asm-arm/thread_info.h +1 -1
@@ -76,7 +76,7 @@
 /*
  * how to get the thread information struct from C
  */
-static inline struct thread_info *current_thread_info(void) __attribute__ (( __const__ ));
+static inline struct thread_info *current_thread_info(void) __attribute_const__;
 
 static inline struct thread_info *current_thread_info(void)
 {

===== include/asm-arm26/current.h 1.1 vs edited =====

include/asm-arm26/current.h +1 -1
@@ -3,7 +3,7 @@
 
 #include <linux/thread_info.h>
 
-static inline struct task_struct *get_current(void) __attribute__ (( __const__ ));
+static inline struct task_struct *get_current(void) __attribute_const__;
 
 static inline struct task_struct *get_current(void)
 {

===== include/asm-arm26/thread_info.h 1.2 vs edited =====

include/asm-arm26/thread_info.h +1 -1
@@ -71,7 +71,7 @@
 /*
  * how to get the thread information struct from C
  */
-static inline struct thread_info *current_thread_info(void) __attribute__ (( __const__ ));
+static inline struct thread_info *current_thread_info(void) __attribute_const__;
 
 static inline struct thread_info *current_thread_info(void)
 {

===== include/asm-m68k/virtconvert.h 1.4 vs edited =====

include/asm-m68k/virtconvert.h +2 -2
@@ -19,8 +19,8 @@
  * Change virtual addresses to physical addresses and vv.
  */
 #ifndef CONFIG_SUN3
-extern unsigned long mm_vtop(unsigned long addr) __attribute__ ((const));
-extern unsigned long mm_ptov(unsigned long addr) __attribute__ ((const));
+extern unsigned long mm_vtop(unsigned long addr) __attribute_const__;
+extern unsigned long mm_ptov(unsigned long addr) __attribute_const__;
 #else
 static inline unsigned long mm_vtop(unsigned long vaddr)
 {

===== include/asm-ppc/io.h 1.14 vs edited =====

include/asm-ppc/io.h +1 -1
@@ -208,7 +208,7 @@
 #define ioremap_nocache(addr, size)	ioremap((addr), (size))
 extern void iounmap(void *addr);
 extern unsigned long iopa(unsigned long addr);
-extern unsigned long mm_ptov(unsigned long addr) __attribute__ ((const));
+extern unsigned long mm_ptov(unsigned long addr) __attribute_const__;
 extern void io_block_mapping(unsigned long virt, phys_addr_t phys,
 			     unsigned int size, int flags);

===== include/asm-ppc/pgtable.h 1.27 vs edited =====

include/asm-ppc/pgtable.h +1 -1
@@ -626,7 +626,7 @@
 extern void cache_push(__u32 addr, int length);
 extern int mm_end_of_chunk (unsigned long addr, int len);
 extern unsigned long iopa(unsigned long addr);
-extern unsigned long mm_ptov(unsigned long addr) __attribute__ ((const));
+extern unsigned long mm_ptov(unsigned long addr) __attribute_const__;
 
 /* Values for nocacheflag and cmode */
 /* These are not used by the APUS kernel_map, but prevents

===== include/asm-sparc/btfixup.h 1.2 vs edited =====

include/asm-sparc/btfixup.h +7 -7
@@ -39,7 +39,7 @@
 	extern __type ___f_##__name(__args);						\
 	extern unsigned ___fs_##__name[3];
 #define BTFIXUPDEF_CALL_CONST(__type, __name, __args...) 				\
-	extern __type ___f_##__name(__args) __attribute__((const));			\
+	extern __type ___f_##__name(__args) __attribute_const__;			\
 	extern unsigned ___fs_##__name[3];
 #define BTFIXUP_CALL(__name) ___f_##__name
 

@@ -49,7 +49,7 @@
 /* Put bottom 13bits into some register variable */
 
 #define BTFIXUPDEF_SIMM13(__name)							\
-	extern unsigned int ___sf_##__name(void) __attribute__((const));		\
+	extern unsigned int ___sf_##__name(void) __attribute_const__;		\
 	extern unsigned ___ss_##__name[2];						\
 	extern __inline__ unsigned int ___sf_##__name(void) {				\
 		unsigned int ret;							\

@@ -57,7 +57,7 @@
 		return ret;								\
 	}
 #define BTFIXUPDEF_SIMM13_INIT(__name,__val)						\
-	extern unsigned int ___sf_##__name(void) __attribute__((const));		\
+	extern unsigned int ___sf_##__name(void) __attribute_const__;		\
 	extern unsigned ___ss_##__name[2];						\
 	extern __inline__ unsigned int ___sf_##__name(void) {				\
 		unsigned int ret;							\

@@ -71,7 +71,7 @@
  */
 
 #define BTFIXUPDEF_HALF(__name)								\
-	extern unsigned int ___af_##__name(void) __attribute__((const));		\
+	extern unsigned int ___af_##__name(void) __attribute_const__;		\
 	extern unsigned ___as_##__name[2];						\
 	extern __inline__ unsigned int ___af_##__name(void) {				\
 		unsigned int ret;							\

@@ -79,7 +79,7 @@
 		return ret;								\
 	}
 #define BTFIXUPDEF_HALF_INIT(__name,__val)						\
-	extern unsigned int ___af_##__name(void) __attribute__((const));		\
+	extern unsigned int ___af_##__name(void) __attribute_const__;		\
 	extern unsigned ___as_##__name[2];						\
 	extern __inline__ unsigned int ___af_##__name(void) {				\
 		unsigned int ret;							\

@@ -90,7 +90,7 @@
 /* Put upper 22 bits into some register variable */
 
 #define BTFIXUPDEF_SETHI(__name)							\
-	extern unsigned int ___hf_##__name(void) __attribute__((const));		\
+	extern unsigned int ___hf_##__name(void) __attribute_const__;		\
 	extern unsigned ___hs_##__name[2];						\
 	extern __inline__ unsigned int ___hf_##__name(void) {				\
 		unsigned int ret;							\

@@ -98,7 +98,7 @@
 		return ret;								\
 	}
 #define BTFIXUPDEF_SETHI_INIT(__name,__val)						\
-	extern unsigned int ___hf_##__name(void) __attribute__((const));		\
+	extern unsigned int ___hf_##__name(void) __attribute_const__;		\
 	extern unsigned ___hs_##__name[2];						\
 	extern __inline__ unsigned int ___hf_##__name(void) {				\
 		unsigned int ret;							\

===== include/asm-sparc/pgtable.h 1.17 vs edited =====

include/asm-sparc/pgtable.h +10 -10
@@ -80,7 +80,7 @@
 BTFIXUPDEF_SETHI(pmd_size)
 BTFIXUPDEF_SETHI(pmd_mask)
 
-extern unsigned int pmd_align(unsigned int addr) __attribute__((const));
+extern unsigned int pmd_align(unsigned int addr) __attribute_const__;
 extern __inline__ unsigned int pmd_align(unsigned int addr)
 {
 	return ((addr + ~BTFIXUP_SETHI(pmd_mask)) & BTFIXUP_SETHI(pmd_mask));

@@ -90,7 +90,7 @@
 BTFIXUPDEF_SETHI(pgdir_size)
 BTFIXUPDEF_SETHI(pgdir_mask)
 
-extern unsigned int pgdir_align(unsigned int addr) __attribute__((const));
+extern unsigned int pgdir_align(unsigned int addr) __attribute_const__;
 extern __inline__ unsigned int pgdir_align(unsigned int addr)
 {
 	return ((addr + ~BTFIXUP_SETHI(pgdir_mask)) & BTFIXUP_SETHI(pgdir_mask));

@@ -248,19 +248,19 @@
 BTFIXUPDEF_HALF(pte_dirtyi)
 BTFIXUPDEF_HALF(pte_youngi)
 
-extern int pte_write(pte_t pte) __attribute__((const));
+extern int pte_write(pte_t pte) __attribute_const__;
 extern __inline__ int pte_write(pte_t pte)
 {
 	return pte_val(pte) & BTFIXUP_HALF(pte_writei);
 }
 
-extern int pte_dirty(pte_t pte) __attribute__((const));
+extern int pte_dirty(pte_t pte) __attribute_const__;
 extern __inline__ int pte_dirty(pte_t pte)
 {
 	return pte_val(pte) & BTFIXUP_HALF(pte_dirtyi);
 }
 
-extern int pte_young(pte_t pte) __attribute__((const));
+extern int pte_young(pte_t pte) __attribute_const__;
 extern __inline__ int pte_young(pte_t pte)
 {
 	return pte_val(pte) & BTFIXUP_HALF(pte_youngi);

@@ -271,7 +271,7 @@
  */
 BTFIXUPDEF_HALF(pte_filei)
 
-extern int pte_file(pte_t pte) __attribute__((const));
+extern int pte_file(pte_t pte) __attribute_const__;
 extern __inline__ int pte_file(pte_t pte)
 {
 	return pte_val(pte) & BTFIXUP_HALF(pte_filei);

@@ -283,19 +283,19 @@
 BTFIXUPDEF_HALF(pte_mkcleani)
 BTFIXUPDEF_HALF(pte_mkoldi)
 
-extern pte_t pte_wrprotect(pte_t pte) __attribute__((const));
+extern pte_t pte_wrprotect(pte_t pte) __attribute_const__;
 extern __inline__ pte_t pte_wrprotect(pte_t pte)
 {
 	return __pte(pte_val(pte) & ~BTFIXUP_HALF(pte_wrprotecti));
 }
 
-extern pte_t pte_mkclean(pte_t pte) __attribute__((const));
+extern pte_t pte_mkclean(pte_t pte) __attribute_const__;
 extern __inline__ pte_t pte_mkclean(pte_t pte)
 {
 	return __pte(pte_val(pte) & ~BTFIXUP_HALF(pte_mkcleani));
 }
 
-extern pte_t pte_mkold(pte_t pte) __attribute__((const));
+extern pte_t pte_mkold(pte_t pte) __attribute_const__;
 extern __inline__ pte_t pte_mkold(pte_t pte)
 {
 	return __pte(pte_val(pte) & ~BTFIXUP_HALF(pte_mkoldi));

@@ -332,7 +332,7 @@
 
 BTFIXUPDEF_INT(pte_modify_mask)
 
-extern pte_t pte_modify(pte_t pte, pgprot_t newprot) __attribute__((const));
+extern pte_t pte_modify(pte_t pte, pgprot_t newprot) __attribute_const__;
 extern __inline__ pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
 	return __pte((pte_val(pte) & BTFIXUP_INT(pte_modify_mask)) |

===== include/linux/reiserfs_fs.h 1.53 vs edited =====

include/linux/reiserfs_fs.h +1 -1
@@ -90,7 +90,7 @@
 #define RFALSE( cond, format, args... ) do {;} while( 0 )
 #endif
 
-#define CONSTF __attribute__( ( const ) )
+#define CONSTF __attribute_const__
 /*
  * Disk Data Structures
  */