Commit 61d73e4f authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86/percpu: Clean up <asm/percpu.h> a bit 



 - Fix misc typos

 - There's 4 variants of the same spelling right now:

     'per-CPU', 'per CPU', 'percpu' and 'per-cpu'

   Standardize on 'per-CPU' only.

 - s/makes gcc load
    /makes the compiler load

 - Instead of:

     #ifdef CONFIG_XXXX
     #define YYYY FOO
     #else
     #define YYYY BAR
     #endif

   Use the slightly more readable form of:

     #ifdef CONFIG_XXXX
     # define YYYY FOO
     #else
     # define YYYY BAR
     #endif

 - Standardize & expand '#else' and '#endif' comments

 - Fix comment style

 - Capitalize x86 instruction names in comments

No change in code.

Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Uros Bizjak <ubizjak@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
parent 47c9dbd2

arch/x86/include/asm/percpu.h

+50 −41
Original line number Diff line number Diff line
@@ -26,7 +26,7 @@ 
# define INIT_PER_CPU_VAR(var)  var

#endif



#else /* ...!ASSEMBLY */

#else /* !__ASSEMBLY__: */



#include <linux/build_bug.h>

#include <linux/stringify.h>
@@ -49,7 +49,7 @@ 


#define __percpu_prefix		""



#else /* CONFIG_CC_HAS_NAMED_AS */

#else /* !CONFIG_CC_HAS_NAMED_AS: */



#define __percpu_seg_override

#define __percpu_prefix		"%%"__stringify(__percpu_seg)":"
@@ -80,7 +80,8 @@ 


#define PER_CPU_VAR(var)	%__percpu_seg:(var)__percpu_rel



#else /* CONFIG_SMP */

#else /* !CONFIG_SMP: */



#define __percpu_seg_override

#define __percpu_prefix		""

#define __force_percpu_prefix	""
@@ -96,7 +97,7 @@ 
#define __force_percpu_arg(x)	__force_percpu_prefix "%" #x



/*

 * Initialized pointers to per-cpu variables needed for the boot

 * Initialized pointers to per-CPU variables needed for the boot

 * processor need to use these macros to get the proper address

 * offset from __per_cpu_load on SMP.

 *
@@ -111,8 +112,10 @@ 
# define init_per_cpu_var(var)  var

#endif



/* For arch-specific code, we can use direct single-insn ops (they

 * don't give an lvalue though). */

/*

 * For arch-specific code, we can use direct single-insn ops (they

 * don't give an lvalue though).

 */



#define __pcpu_type_1 u8

#define __pcpu_type_2 u16
@@ -158,7 +161,7 @@ do { \ 


#define __raw_cpu_read_const(pcp)	__raw_cpu_read(, , pcp)



#else /* CONFIG_USE_X86_SEG_SUPPORT */

#else /* !CONFIG_USE_X86_SEG_SUPPORT: */



#define __raw_cpu_read(size, qual, _var)				\

({									\
@@ -183,7 +186,7 @@ do { \ 
} while (0)



/*

 * The generic per-cpu infrastrucutre is not suitable for

 * The generic per-CPU infrastrucutre is not suitable for

 * reading const-qualified variables.

 */

#define __raw_cpu_read_const(pcp)	({ BUILD_BUG(); (typeof(pcp))0; })
@@ -219,7 +222,7 @@ do { \ 
} while (0)



/*

 * Generate a percpu add to memory instruction and optimize code

 * Generate a per-CPU add to memory instruction and optimize code

 * if one is added or subtracted.

 */

#define percpu_add_op(size, qual, var, val)				\
@@ -266,9 +269,9 @@ do { \ 
})



/*

 * this_cpu_xchg() is implemented using cmpxchg without a lock prefix.

 * xchg is expensive due to the implied lock prefix. The processor

 * cannot prefetch cachelines if xchg is used.

 * this_cpu_xchg() is implemented using CMPXCHG without a LOCK prefix.

 * XCHG is expensive due to the implied LOCK prefix. The processor

 * cannot prefetch cachelines if XCHG is used.

 */

#define this_percpu_xchg_op(_var, _nval)				\

({									\
@@ -278,8 +281,8 @@ do { \ 
})



/*

 * cmpxchg has no such implied lock semantics as a result it is much

 * more efficient for cpu local operations.

 * CMPXCHG has no such implied lock semantics as a result it is much

 * more efficient for CPU-local operations.

 */

#define percpu_cmpxchg_op(size, qual, _var, _oval, _nval)		\

({									\
@@ -314,6 +317,7 @@ do { \ 
})



#if defined(CONFIG_X86_32) && !defined(CONFIG_UML)



#define percpu_cmpxchg64_op(size, qual, _var, _oval, _nval)		\

({									\

	union {								\
@@ -374,7 +378,8 @@ do { \ 


#define raw_cpu_try_cmpxchg64(pcp, ovalp, nval)		percpu_try_cmpxchg64_op(8,         , pcp, ovalp, nval)

#define this_cpu_try_cmpxchg64(pcp, ovalp, nval)	percpu_try_cmpxchg64_op(8, volatile, pcp, ovalp, nval)

#endif



#endif /* defined(CONFIG_X86_32) && !defined(CONFIG_UML) */



#ifdef CONFIG_X86_64

#define raw_cpu_cmpxchg64(pcp, oval, nval)	percpu_cmpxchg_op(8,         , pcp, oval, nval);
@@ -443,7 +448,8 @@ do { \ 


#define raw_cpu_try_cmpxchg128(pcp, ovalp, nval)	percpu_try_cmpxchg128_op(16,         , pcp, ovalp, nval)

#define this_cpu_try_cmpxchg128(pcp, ovalp, nval)	percpu_try_cmpxchg128_op(16, volatile, pcp, ovalp, nval)

#endif



#endif /* CONFIG_X86_64 */



#define raw_cpu_read_1(pcp)		__raw_cpu_read(1, , pcp)

#define raw_cpu_read_2(pcp)		__raw_cpu_read(2, , pcp)
@@ -510,8 +516,8 @@ do { \ 
#define this_cpu_try_cmpxchg_4(pcp, ovalp, nval)	percpu_try_cmpxchg_op(4, volatile, pcp, ovalp, nval)



/*

 * Per cpu atomic 64 bit operations are only available under 64 bit.

 * 32 bit must fall back to generic operations.

 * Per-CPU atomic 64-bit operations are only available under 64-bit kernels.

 * 32-bit kernels must fall back to generic operations.

 */

#ifdef CONFIG_X86_64

#define raw_cpu_read_8(pcp)		__raw_cpu_read(8, , pcp)
@@ -539,20 +545,23 @@ do { \ 
#define this_cpu_try_cmpxchg_8(pcp, ovalp, nval)	percpu_try_cmpxchg_op(8, volatile, pcp, ovalp, nval)



#define raw_cpu_read_long(pcp)		raw_cpu_read_8(pcp)

#else

/* There is no generic 64 bit read stable operation for 32 bit targets. */



#else /* !CONFIG_X86_64: */



/* There is no generic 64-bit read stable operation for 32-bit targets. */

#define this_cpu_read_stable_8(pcp)	({ BUILD_BUG(); (typeof(pcp))0; })



#define raw_cpu_read_long(pcp)		raw_cpu_read_4(pcp)

#endif



#endif /* CONFIG_X86_64 */



#define this_cpu_read_const(pcp)	__raw_cpu_read_const(pcp)



/*

 * this_cpu_read() makes gcc load the percpu variable every time it is

 * accessed while this_cpu_read_stable() allows the value to be cached.

 * this_cpu_read() makes the compiler load the per-CPU variable every time

 * it is accessed while this_cpu_read_stable() allows the value to be cached.

 * this_cpu_read_stable() is more efficient and can be used if its value

 * is guaranteed to be valid across cpus.  The current users include

 * is guaranteed to be valid across CPUs.  The current users include

 * pcpu_hot.current_task and pcpu_hot.top_of_stack, both of which are

 * actually per-thread variables implemented as per-CPU variables and

 * thus stable for the duration of the respective task.
@@ -631,7 +640,7 @@ DECLARE_PER_CPU_READ_MOSTLY(unsigned long, this_cpu_off); 
		&early_per_cpu_ptr(_name)[_cpu] :		\

		&per_cpu(_name, _cpu))



#else	/* !CONFIG_SMP */

#else /* !CONFIG_SMP: */

#define	DEFINE_EARLY_PER_CPU(_type, _name, _initvalue)		\

	DEFINE_PER_CPU(_type, _name) = _initvalue
@@ -651,6 +660,6 @@ DECLARE_PER_CPU_READ_MOSTLY(unsigned long, this_cpu_off); 
#define	early_per_cpu_ptr(_name) NULL

/* no early_per_cpu_map() */



#endif	/* !CONFIG_SMP */

#endif /* CONFIG_SMP */



#endif /* _ASM_X86_PERCPU_H */