On 20 February 2013 14:59, Paolo Bonzini <pbonz...@redhat.com> wrote: > Il 20/02/2013 15:49, Peter Maydell ha scritto: >> On 20 February 2013 14:43, Laszlo Ersek <ler...@redhat.com> wrote: >>> On 02/20/13 14:43, Paolo Bonzini wrote: >>>> QEMU system emulation has been thread-safe for a long time >> >> Says who? cpu_interrupt() calls tcg_handle_interrupt() >> which calls cpu_unlink_tb() which makes changes to the >> TB datastructure with no kind of locking at all. > > But in system emulation mode, cpu_interrupt is always running under the > iothread lock.
Mmm, true (and in any case tcg_handle_interrupt() does kick-and-return if it's not the cputhread). > cpu_exit is more interesting because it calls cpu_unlink_tb() outside > the iothread lock. However, it does this in a signal handler running in > the CPU thread (or, in Windows, wrapped with > SuspendThread/ResumeThread). So it "only" needs to be > async-signal-safe, not thread-safe. It's not async-signal-safe, though :-) -- PMM
