Commit e0eeb938 authored by Dan Carpenter's avatar Dan Carpenter Committed by Yury Norov
Browse files

bitops: Add a comment explaining the double underscore macros 

Linus Walleij pointed out that a new comer might be confused about the
difference between set_bit() and __set_bit().  Add a comment explaining
the difference.

Link: https://lore.kernel.org/all/CACRpkdZFPG_YLici-BmYfk9HZ36f4WavCN3JNotkk8cPgCODCg@mail.gmail.com/


Signed-off-by: default avatarDan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarYury Norov <yury.norov@gmail.com>
parent e334771d

include/linux/bitops.h

+5 −0
Original line number Diff line number Diff line
@@ -47,12 +47,17 @@ extern unsigned long __sw_hweight64(__u64 w); 
	  __builtin_constant_p(*(const unsigned long *)(addr))) ?	\

	 const##op(nr, addr) : op(nr, addr))



/*

 * The following macros are non-atomic versions of their non-underscored

 * counterparts.

 */

#define __set_bit(nr, addr)		bitop(___set_bit, nr, addr)

#define __clear_bit(nr, addr)		bitop(___clear_bit, nr, addr)

#define __change_bit(nr, addr)		bitop(___change_bit, nr, addr)

#define __test_and_set_bit(nr, addr)	bitop(___test_and_set_bit, nr, addr)

#define __test_and_clear_bit(nr, addr)	bitop(___test_and_clear_bit, nr, addr)

#define __test_and_change_bit(nr, addr)	bitop(___test_and_change_bit, nr, addr)



#define test_bit(nr, addr)		bitop(_test_bit, nr, addr)

#define test_bit_acquire(nr, addr)	bitop(_test_bit_acquire, nr, addr)