Messages in this thread | | | Date | Mon, 28 Nov 2005 21:31:29 +0530 | From | Dipankar Sarma <> | Subject | Re: [PATCH] Allow lockless traversal of notifier lists |
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On Mon, Nov 28, 2005 at 02:37:57PM +0100, Andi Kleen wrote: > > As discussed in other thread. > > Just needed an additional write barrier, so that a parallel > running lockup can never see inconsistent state. As long as there > is no unregistration or the unregistration is done using > locking or RCU in the caller they should be ok now. > > This only makes a difference on non i386/x86-64 architectures. > x86 was already ok because it never reorders writes. > > * > * Currently always returns zero. > */ > @@ -116,6 +119,7 @@ > list= &((*list)->next); > } > n->next = *list; > + wmb(); > *list=n; > write_unlock(¬ifier_lock);
Shouldn't this be smp_wmb() ?
Also, not all archs have strong ordering for data dependent reads. So, you would probably need an smp_read_barrier_depends() between the load of the pointer and actual dereferencing.
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