LDREX/STREX and pre-emption on SMP hardware

[Catalin Marinas]

On Mon, 2009-09-14 at 11:06 +0100, Catalin Marinas wrote:
> On Mon, 2009-09-14 at 11:00 +0100, Russell King - ARM Linux wrote:
> > It doesn't matter though - consider two threads using LDREX on the same
> > location:
> > 
> > 	T1		T2
> > 	LDREX
> > 			LDREX
> > 			STREXEQ (not satsified)
> > 	STREX
> 
> As I replied to Jamie on a similar issue, you can have:
> 
> T1			T2
> LDREX
> 			LDREX
> 			STREXEQ (satisfied, succeeds)
> 			LDREX
> 			STREXEQ (not satisfied)
> STREX (succeeds)
> 
> Though this may be an unlikely sequence.

Searching for STREXEQ, it looks like there are several other locking
functions using it in spinlock.h. Do we have a real problem with these?

-- 
Catalin