Messages in this thread | | | Date | Tue, 1 Aug 2017 18:45:20 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/3] jump_labels: fix concurrent static_key_enable/disable() |
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Thanks for doing these patches, I hadn't come around to them yet.
On Tue, Aug 01, 2017 at 05:24:04PM +0200, Paolo Bonzini wrote: > > +void static_key_enable(struct static_key *key) > +{ > + STATIC_KEY_CHECK_USE(); > + if (atomic_read(&key->enabled) > 0) { > + WARN_ON_ONCE(atomic_read(&key->enabled) != 1); > + return; > + } > + > + cpus_read_lock(); > + jump_label_lock(); > + if (atomic_read(&key->enabled) == 0) { > + atomic_set(&key->enabled, -1); > + jump_label_update(key);
As per the previous discussion, should I do a patch adding barriers here (or using atomic_set_release()) such that we close the window where a concurrent inc/enable sees 1 but not all text changes?
> + atomic_set(&key->enabled, 1); > + } > + jump_label_unlock(); > + cpus_read_unlock(); > +} > +EXPORT_SYMBOL_GPL(static_key_enable);
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