Re: [PATCH] make atomic_t volatile on all architectures

On Thu, 2007-08-09 at 13:36 -0400, Chuck Ebbert wrote:
> > Fair enough.  Casting to (volatile int *) will give us the behavior
> > people expect when using atomic_t without needing to use inefficient
> > barriers.
> > 
> 
> You can use this forget() macro to make the compiler reread a
> variable:
> 
> #define forget(var) asm volatile ("" : "=m"(var))

You need to specify a "m"(var) input constraint as well. Without it the
compiler might remove the initialization of var. E.g.

void fn(void)
{
	int var = 0;
	forget(var);
	/* now var can have any value. */
}

-- 
blue skies,
  Martin.

"Reality continues to ruin my life." - Calvin.


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---

• References:
  • [PATCH] make atomic_t volatile on all architectures
    • From: Chris Snook <[email protected]>
  • Re: [PATCH] make atomic_t volatile on all architectures
    • From: Linus Torvalds <[email protected]>
  • Re: [PATCH] make atomic_t volatile on all architectures
    • From: Chris Snook <[email protected]>
  • Re: [PATCH] make atomic_t volatile on all architectures
    • From: Chuck Ebbert <[email protected]>

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