Messages in this thread | | | Date | Fri, 20 Feb 2015 21:02:26 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 6/7 linux-next] wan: cosa: replace current->state by set_current_state() |
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On Fri, Feb 20, 2015 at 11:31:53AM -0800, Eric Dumazet wrote: > On Fri, 2015-02-20 at 19:58 +0100, Peter Zijlstra wrote:
> Maybe this might be self documented in set_current_state(), > as we have about 120 calls to __set_current_state(TASK_RUNNING) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 41c60e5302d7..26133da6445e 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -275,7 +275,11 @@ extern char ___assert_task_state[1 - 2*!!( > #define set_current_state(state_value) \ > do { \ > current->task_state_change = _THIS_IP_; \ > - set_mb(current->state, (state_value)); \ > + if (__builtin_constant_p(state_value) && \ > + (state_value) == TASK_RUNNING) \ > + current->state = (state_value); \ > + else \ > + set_mb(current->state, (state_value)); \ > } while (0)
lkml.kernel.org/r/20150206163947.GR21418@twins.programming.kicks-ass.net
The problem is that there _might_ be someone relying on that barrier.
Its (very) unlikely, but you don't want to risk subtle borkage just because. And I'm too lazy to go audit all of them :/
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