On Wed, Mar 12, 2014 at 12:03:19AM +0000, Peter Maydell wrote: > On 11 March 2014 23:58, Andreas Färber <afaer...@suse.de> wrote: > > Am 20.02.2014 16:58, schrieb Peter Maydell: > >> On 16 February 2014 02:07, Edgar E. Iglesias <edgar.igles...@gmail.com> > >> wrote: > >>> On Sat, Feb 15, 2014 at 03:42:56PM +0000, Peter Maydell wrote: > >>>> On 13 February 2014 05:07, <edgar.igles...@gmail.com> wrote: > >>>>> From: "Edgar E. Iglesias" <edgar.igles...@xilinx.com> > >>>>> > >>>>> cpu->exit_request is part of the execution environment and should > >>>>> not be cleared when a CPU resets. > >>>>> > >>>>> Otherwise, we might deadlock QEMU if a CPU resets while there is > >>>>> I/O going on. > >>>>> > >>>>> Signed-off-by: Edgar E. Iglesias <edgar.igles...@xilinx.com> > >>>>> --- > >>>>> qom/cpu.c | 1 - > >>>>> 1 file changed, 1 deletion(-) > >>>>> > >>>>> diff --git a/qom/cpu.c b/qom/cpu.c > >>>>> index 9d62479..40d82dd 100644 > >>>>> --- a/qom/cpu.c > >>>>> +++ b/qom/cpu.c > >>>>> @@ -195,7 +195,6 @@ static void cpu_common_reset(CPUState *cpu) > >>>>> log_cpu_state(cpu, cc->reset_dump_flags); > >>>>> } > >>>>> > >>>>> - cpu->exit_request = 0; > >>>>> cpu->interrupt_request = 0; > >>>>> cpu->current_tb = NULL; > >>>>> cpu->halted = 0; > >>>> > >>>> This looks kind of odd to me. What's the situation you see where > >>>> this matters -- is the CPU resetting itself, or is some other device > >>>> in another thread triggering the CPU reset? TCG or KVM? > >>> > >>> Seeing this in TCG. The CPU gets signaled by the IO thread while the > >>> CPU is resetting itself. If the CPU looses the race, it clears its > >>> exit_request leaving the IO thread waiting for the global lock > >>> potentially forever. > >>> > >>> The CPU actually exits generated code but goes right back in because > >>> there is no exit_request pending. > >> > >> Yes, having looked at the code I agree with you, so: > >> > >> Reviewed-by: Peter Maydell <peter.mayd...@linaro.org> > > > > Thanks, applied to qom-cpu (with clarified commit message): > > https://github.com/afaerber/qemu-cpu/commits/qom-cpu > > I'd forgotten about this, but it's a bugfix for a hang, right?
Hi, yes it's a bugfix for a hang. > Seems to me like we ought to put it into 2.0 -- were you Makes sense to me Thanks, Edgar > planning to submit it via qom-cpu for 2.0? > > thanks > -- PMM
