Messages in this thread | | | Date | Wed, 22 Sep 2021 08:32:08 +0200 | From | Sebastian Andrzej Siewior <> | Subject | Re: rcu/tree: Protect rcu_rdp_is_offloaded() invocations on RT |
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On 2021-09-22 01:45:18 [+0200], Frederic Weisbecker wrote: > > Also while at it, I'm asking again: traditionally softirqs could assume that > manipulating a local state was safe against !irq_count() code fiddling with > the same state on the same CPU. > > Now with preemptible softirqs, that assumption can be broken anytime. RCU was > fortunate enough to have a warning for that. But who knows how many issues like > this are lurking?
If "local state" is modified then it is safe as long as it is modified within a local_bh_disable() section. And we are in this section while invoking a forced-threaded interrupt. The special part about RCU is that it is used in_irq() as part of core-code.
> Thanks.
Sebastian
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