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Date: Tue, 23 Jun 2015 11:49:33 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 6/9] kvm: First step to push iothread lock
 out of inner run loop
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To: Fam Zheng <famz@redhat.com>
Cc: jan.kiszka@siemens.com, qemu-devel@nongnu.org



On 23/06/2015 11:45, Fam Zheng wrote:
>>> > >            break;
>>> > >        case KVM_EXIT_SYSTEM_EVENT:
>>> > >            switch (run->system_event.type) {
>>> > >            case KVM_SYSTEM_EVENT_SHUTDOWN:
>>> > > *              qemu_system_shutdown_request();
>>> > >                ret = EXCP_INTERRUPT;
>>> > >                break;
>>> > >            case KVM_SYSTEM_EVENT_RESET:
>>> > > *              qemu_system_reset_request();
>> > 
>> > These two are thread-safe.
> But above you add lock/unlock around the qemu_system_reset_request() under
> KVM_EXIT_SHUTDOWN.  What's different?

That's unnecessary.

Also, just below this switch there's another call to
kvm_arch_handle_exit that should be wrapped by lock/unlock (it works
anyway because no one handles KVM_EXIT_SYSTEM_EVENT in
kvm_arch_handle_exit, but it's not clean).

Paolo