Messages in this thread | | | Subject | Re: [PATCH 1/3] jump_labels: fix concurrent static_key_enable/disable() | From | Paolo Bonzini <> | Date | Tue, 1 Aug 2017 18:46:18 +0200 |
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On 01/08/2017 18:45, Peter Zijlstra wrote: > > 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?
Sure, and that applies to static_key_slow_inc as well.
Paolo
>> + atomic_set(&key->enabled, 1); >> + } >> + jump_label_unlock(); >> + cpus_read_unlock(); >> +} >> +EXPORT_SYMBOL_GPL(static_key_enable);
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