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SubjectRe: PATCH: Race in 2.6.0-test2 timer code
On Wed, Jul 30, 2003 at 09:34:40AM +0200, Ingo Molnar wrote:
>
> On Wed, 30 Jul 2003, Andrea Arcangeli wrote:
>
> > The thing triggered simply by running setitimer in one function, while
> > the it_real_fn was running in the other cpu. I don't see how 2.6 can
> > have fixed this, it_real_fun can still trivially call add_timer while
> > you run inside do_setitimer in 2.6 too. [...]
>
> This is not a race that can happen. itimer does this:
>
> del_timer_sync();
> add_timer();
>
> how can the add_timer() still happen while it_real_fn is still running on
> another CPU?

it's not add_timer against add_timer in this case, it's del_timer_sync
against add_timer.


cpu0 cpu1
------------ --------------------

do_setitimer
it_real_fn
del_timer_sync add_timer -> crash

Andrea
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