On 24/09/2016 22:43, Richard Henderson wrote: >>> I don't see that the cpu_list_lock protects the >>> last two lines in any way. >> >> It does: >> >> qemu_mutex_lock(&qemu_cpu_list_lock); > > What I meant is that I don't see that the mutex avoids the need for > atomic_set.
Oh, I see. cpu->running is only read under the mutex, but can be written _by the owner thread only_ outside the mutex. So writes outside the mutex must be atomic, but writes under the mutex don't because: - no other thread ever writes to cpu->running - no other thread can be reading cpu->running Paolo
