Re: [kvm-unit-tests PATCH v3 1/8] arch-run: Fix TRAP handler recursion to remove temporary files properly

Thomas Huth
2024-02-09T07:29:15Z

On 09/02/2024 08.01, Nicholas Piggin wrote:
> Migration files were not being removed when the QEMU process is
> interrupted (e.g., with ^C). This is becaus the SIGINT propagates to the
> bash TRAP handler, which recursively TRAPs due to the 'kill 0' in the
> handler. This eventually crashes bash.
>
> This can be observed by interrupting a long-running test program that is
> run with MIGRATION=yes, /tmp/mig-helper-* files remain afterwards.
>
> Removing TRAP recursion solves this problem and allows the EXIT handler
> to run and clean up the files.
>
> This also moves the trap handler before temp file creation, and expands
> the name variables at trap-time rather than install-time, which closes
> the small race between creation trap handler install.
>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> scripts/arch-run.bash | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/scripts/arch-run.bash b/scripts/arch-run.bash
> index d0864360..11d47a85 100644
> --- a/scripts/arch-run.bash
> +++ b/scripts/arch-run.bash
> @@ -129,6 +129,9 @@ run_migration ()
> return 77
> fi
>
> + trap 'trap - TERM ; kill 0 ; exit 2' INT TERM
> + trap 'rm -f ${migout1} ${migsock} ${qmp1} ${qmp2} ${fifo}' RETURN EXIT
> +
> migsock=$(mktemp -u -t mig-helper-socket.XXXXXXXXXX)
> migout1=$(mktemp -t mig-helper-stdout1.XXXXXXXXXX)
> qmp1=$(mktemp -u -t mig-helper-qmp1.XXXXXXXXXX)
> @@ -137,9 +140,6 @@ run_migration ()
> qmpout1=/dev/null
> qmpout2=/dev/null
>
> - trap 'kill 0; exit 2' INT TERM
> - trap 'rm -f ${migout1} ${migsock} ${qmp1} ${qmp2} ${fifo}' RETURN EXIT
> -
> eval "$@" -chardev socket,id=mon1,path=${qmp1},server=on,wait=off \
> -mon chardev=mon1,mode=control | tee ${migout1} &
> live_pid=`jobs -l %+ | grep "eval" | awk '{print$2}'`
> @@ -209,11 +209,11 @@ run_panic ()
> return 77
> fi
>
> - qmp=$(mktemp -u -t panic-qmp.XXXXXXXXXX)
> -
> - trap 'kill 0; exit 2' INT TERM
> + trap 'trap - TERM ; kill 0 ; exit 2' INT TERM
> trap 'rm -f ${qmp}' RETURN EXIT
>
> + qmp=$(mktemp -u -t panic-qmp.XXXXXXXXXX)
> +
> # start VM stopped so we don't miss any events
> eval "$@" -chardev socket,id=mon1,path=${qmp},server=on,wait=off \
> -mon chardev=mon1,mode=control -S &

Reviewed-by: Thomas Huth <thuth@redhat.com>