Re: rcu/tree: Protect rcu_rdp_is_offloaded() invocations on RT
From: Valentin Schneider <hidden>
Date: 2021-09-30 13:22:49
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linux-rt-users, lkml, rcu
On 30/09/21 12:53, Frederic Weisbecker wrote:
On Thu, Sep 30, 2021 at 10:00:39AM +0100, Valentin Schneider wrote:quoted
My reasoning for adding protection in the outer functions was to prevent impaired unlocks of rcu_nocb_{un}lock_irqsave(), as that too depends on the offload state. Cf. Frederic's writeup: http://lore.kernel.org/r/20210727230814.GC283787@lothringen (local)I was wrong about that BTW! Because rcu_nocb_lock() always require IRQs to be disabled, which of course disables preemption, so the offloaded state can't change between rcu_nocb_lock[_irqsave]() and rcu_nocb_unlock[_irqrestore]() but anyway there were many other issues to fix :-)
Ooooh... Even with you pointing it out, it took me a while to see it that way. It's tough to get out of holidays mode :-) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel