Re: [PATCH for-5.2 05/10] vhost-user-blk-test: close fork child file descriptors

[Coiby Xu]

Hi Stefan,

On Wed, Nov 11, 2020 at 12:43:26PM +0000, Stefan Hajnoczi wrote:
> Do not leave stdin and stdout open after fork. stdout is the
> tap-driver.pl pipe. If we keep the pipe open then tap-driver.pl will not
> detect that qos-test has terminated and it will hang.

I wonder under which situation this would happen. I couldn't re-produce
this issue locally.

> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> tests/qtest/vhost-user-blk-test.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/tests/qtest/vhost-user-blk-test.c 
> b/tests/qtest/vhost-user-blk-test.c
> index f05f14c192..4019a72ac0 100644
> --- a/tests/qtest/vhost-user-blk-test.c
> +++ b/tests/qtest/vhost-user-blk-test.c
> @@ -749,6 +749,15 @@ static char *start_vhost_user_blk(GString *cmd_line, int 
> vus_instances,
>                    storage_daemon_command->str);
>     pid_t pid = fork();
>     if (pid == 0) {
> +        /*
> +         * Close standard file descriptors so tap-driver.pl pipe detects when
> +         * our parent terminates.
> +         */
> +        close(0);
> +        close(1);
> +        open("/dev/null", O_RDONLY);
> +        open("/dev/null", O_WRONLY);
> +
>         execlp("/bin/sh", "sh", "-c", storage_daemon_command->str, NULL);
>         exit(1);
>     }
> --
> 2.28.0

--
Best regards,
Coiby