On Wed, 24 Jul 2002, Chris Wright wrote: > * David Wheeler (dwheelerat_private) wrote: > > James Morris said: > > > > > The patch below implements locking of for the security module > > > registration interfaces, covering writing & testing of the > > security_ops pointer. > > > > This patch solves a DIFFERENT problem than the one I'm concerned about; > > it DOES NOT solve the problem I raised earlier if there are multiple > > CPUs which don't guarantee atomic pointer writes. > > I think it does. Look at the way parisc implements xchg(). > Nope, David was correct. The spinlocking only imposes memory ordering with respect to its lock and critical region, which doesn't help us if pointer assignments are not atomic. The locking is still needed for unprotected use of the registration interface, though. However, I have been told by one of the kernel port maintainers that pointer assignments will always be atomic where the pointers are aligned correctly, for all current archs. This means we should be ok, as the pointers we are using will be aligned correctly by the compiler. - James -- James Morris <jmorrisat_private> _______________________________________________ linux-security-module mailing list linux-security-moduleat_private http://mail.wirex.com/mailman/listinfo/linux-security-module
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