On Mon, 10 Feb 2014, Chuansheng Liu wrote:
> There is below race between irq handler and irq thread:
> irq handler irq thread
>
> irq_wake_thread() irq_thread()
> set bit RUNTHREAD
> ... clear bit RUNTHREAD
> thread_fn()
> [A]test_and_decrease
> thread_active
> [B]increase thread_active
>
> If action A is before action B, after that the thread_active
> will be always > 0, and for synchronize_irq() calling, which
> will be waiting there forever.
No. thread_active is 0, simply because after the atomic_dec_and_test()
it is -1 and the atomic_inc on the other side will bring it back to 0.
Thanks,
tglx
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