On 21 March 2014 14:51, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote: > @Catalin: We have a problem here and need your expert advice. After changing > CPU frequency we need to call this code: > > cpufreq_notify_post_transition(); > policy->transition_ongoing = false; > > And the sequence must be like this only. Is this guaranteed without any > memory barriers? cpufreq_notify_post_transition() isn't touching > transition_ongoing at all.. For others this is what we discussed on IRC (rmk: Russell King) <rmk> I'm no barrier expert, but the compiler can't reorder that assignment across a function call which it knows nothing about (which it can't know anything about because it calls other functions through function pointers) <rmk> however, the CPU could re-order the effects with respect to other agents (cpus/devices) when they look at the memory <rmk> for the local CPU, the question is really: what does the C language virtual machine say about this - that's what really matters. If the CPU does speculative stuff, it still has to make the machine behaviour fit that model. -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
