[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v2] cpu-exec: Exit exclusive region on longjmp f
From: |
Emilio G. Cota |
Subject: |
Re: [Qemu-devel] [PATCH v2] cpu-exec: Exit exclusive region on longjmp from step_atomic |
Date: |
Thu, 2 Nov 2017 13:15:38 -0400 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Thu, Nov 02, 2017 at 16:35:36 +0000, 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>
Reviewed-by: Emilio G. Cota <address@hidden>
Good catch, thanks for the fix!
E.