Re: sequence lock in Linux

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Fri, Jun 11, 2010 at 02:38:59PM -0700, H. Peter Anvin wrote:
> On 06/11/2010 02:36 PM, Paul E. McKenney wrote:
> > Memory barriers in the sequence-lock code prevent this, assuming, as
> > you point out, that memory clobber works (but if it doesn't, it should
> > be fixed):
> 
> The constness is my main concern.  It's not clear to me that "memory" is
> meant to imply that const memory areas without volatile can be clobbered.

Ah!  I was assuming that gcc treated "memory" as it would an call to
a function in some other compilation unit.  In that case, the compiler
could not count on the "const" on the argument, given the possibility
that the called function might gain a reference to the same memory
locations in a non-const manner, right?

							Thanx, Paul