Re: [RFC][PATCH v3 2/6] mm, directio: fix fork vs direct-io race(read(2) side IOW gup(write) side)

[Andrea Arcangeli]

On Tue, Apr 14, 2009 at 02:10:08PM -0400, Jeff Moyer wrote:
> Really?  I don't actually see that in the code, have I missed it?

Checking the spinlock version, when any writer is waiting, the
sem->wait_list won't empty and down_read will wait too. The wakeup is
FIFO with __rwsem_do_wake is doing a wake-one if first one in queue is
a down_write. So it looks ok to me. asm version should have an
equivalent logic.
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