Re: Questions about the buffer+page cache in 2.4.0

[Andi Kleen]

On Thu, Jul 27, 2000 at 08:02:50PM +0200, Daniel Phillips wrote:
> So now it's time to start asking questions.  Just jumping in at a place I felt I
> knew pretty well back in 2.2.13, I'm now looking at the 2.4.0 getblk, and I see
> it's changed somewhat.  Finding and removing a block from the free list is now
> bracketed by a spinlock pair.  First question: why do we use atomic_set to set
> the initial buffer use count if this is already protected by a spinlock?

The buffer use count needs to be atomic in other places because interrupts
may change it on UP. atomic_t can only be modified by atomic_* functions 
and atomic.h is lacking a "atomic_set_nonatomic". So even when you only 
need the atomic property once you have to change all uses of the field.


-Andi

-- 
This is like TV. I don't like TV.