Messages in this thread | | | Date | Tue, 16 Mar 2010 14:13:36 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH -tip] introduce sys_membarrier(): process-wide memory barrier (v9) |
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* Nick Piggin <npiggin@suse.de> wrote:
> On Tue, Mar 16, 2010 at 08:36:35AM +0100, Ingo Molnar wrote: > > > > * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote: > > > > > Unless this question is answered, Ingo's SA_RUNNING signal proposal, as > > > appealing as it may look at a first glance, falls into the > > > "fundamentally broken" category. [...] > > > > How is it different from your syscall? I.e. which lines of code make the > > difference? We could certainly apply the (trivial) barrier change to > > context_switch(). > > I think it is just easy for userspace to misuse or think it does something > that it doesn't (because of races).
That wasnt my question though. The question i asked Mathieu was to show how SA_RUNNING is "fundamentally broken" for librcu use while sys_membarrier() is not?
This is really what he claims above. (i preserved the quote)
It must be a misunderstanding either on my side or on his side. (Once that is cleared we can discuss further usecases for SA_RUNNING.)
Thanks,
Ingo
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