Messages in this thread | | | Subject | Re: PATCH? hrtimer_wakeup: fix a theoretical race wrt rt_mutex_slowlock() | From | Benjamin Herrenschmidt <> | Date | Mon, 06 Nov 2006 19:57:51 +1100 |
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> Yes. On x86 (and x86-64) you'll never see this, because writes are always > seen in order regardless, and in addition, the spin_lock is actually > totally serializing anyway. On most other architectures, the spin_lock > will serialize all the writes too, but it's not guaranteed, so in theory > you're right. I suspect no actual architecture will do this, but hey, > when talking memory ordering, safe is a lot better than sorry.
PowerPC doesn't serialize the writes on spin_lock, only on spin_unlock.
(That is, previous writes can "leak" into the lock, but writes done before the unlock can't leak out of the spinlock).
Now, I've just glanced at the thread, so I don't know if that's relevant to the problems you guys are talking about :-)
Ben.
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