atomic.h vs spinlock.h

Hi -
2 questions actually:

1) what is the difference between the macros defined in asm/atomic.h and asm/spinlock.h. (usage and purpose wise)?

2) If I need to use asm/atomic.h, which macro can I use to test-and-set?

thanks,
Umut

Umut> 1) what is the difference between the macros defined in Umut> asm/atomic.h and asm/spinlock.h. (usage and purpose wise)?

The first provides atomic operations, such as increment and decrement; the second provides spinlocks. I'm afraid I'm just stating the obvious here.

In case you have a copy of my book (ia64 linux kernel), atomic ops and spinlocks are described in sections 3.3.2 and 3.3.5, respectively. (Of course, I wouldn't recommend to get the book _just_ because of this.)

Umut> 2) If I need to use asm/atomic.h, which macro can I use to Umut> test-and-set?

cmpxchg() is the closest thing to test-and-set. Not all platforms support it. Platforms that do support it (such as ia64), define macro __HAVE_ARCH_CMPXCHG.

	--david