Re: [Qemu-devel] [PATCH v2] cpu-exec: Exit exclusive region on longjmp from step_atomic

[Richard Henderson]

On 11/02/2017 05:35 PM, Peter Maydell wrote:
> Commit ac03ee5331612e44be narrowed the scope of the exclusive
> region so it only covers when we're executing the TB, not when
> we're generating it. However it missed that there is more than
> one execution path out of cpu_tb_exec -- if the atomic insn
> causes an exception then the code will longjmp out, skipping
> the code to end the exclusive region. This causes QEMU to hang
> the next time the CPU calls start_exclusive(), waiting for
> itself to exit the region.
> 
> Move the "end the region" code out to the end of the
> function so that it is run for both normal exit and also
> for exit-via-longjmp. We have to use a volatile bool flag
> to decide whether we need to end the region, because we
> can longjump out of the codegen as well as the execution.
> 
> (For some reason this only reproduces for me with a clang
> optimized build, not a gcc debug build.)
> 
> Fixes: ac03ee5331612e44beb393df2b578c951d27dc0d
> Signed-off-by: Peter Maydell <address@hidden>
> ---
> Changes v1->v2: use a flag so we get the "longjump out of the
> codegen" case right.

Reviewed-by: Richard Henderson <address@hidden>

I've got one other tcg patch queued for 2.11.
I could take this via tcg-next if you like.


r~