On Thu, Oct 12, 2017 at 04:22:06PM +0300, Imre Deak wrote:
> The clone() system call with a larger executable (like /bin/sh) may have
> difficulty to make progress on some platforms if interrupted frequently.
> So suspend the signal helper process for the duration of the syscall.
> This is needed to solve an actual problem by the next patch.
>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
Your patch prefix is wrong, which means CI wont' pick this up. Please
resubmit with i-g-t as patch thing per our CONTRIBUTING file.
Thanks, Daniel
PS: Yes we'll soon have a separate mailing list for igt to avoid this kind
of fun.
-Daniel
> ---
> lib/igt_aux.c | 38 ++++++++++++++++++++++++++++++++++++++
> lib/igt_aux.h | 2 ++
> lib/igt_core.c | 9 +++++++++
> 3 files changed, 49 insertions(+)
>
> diff --git a/lib/igt_aux.c b/lib/igt_aux.c
> index fa6594c3..36dfab43 100644
> --- a/lib/igt_aux.c
> +++ b/lib/igt_aux.c
> @@ -350,6 +350,44 @@ void igt_stop_signal_helper(void)
> sig_stat = 0;
> }
>
> +/**
> + * igt_suspend_signal_helper:
> + *
> + * Suspends the child process spawned with igt_fork_signal_helper().
> + *
> + * This should be called before code that has difficulty to make progress if
> + * interrupted frequently, like the clone() syscall spawning a large
> + * executable.
> + */
> +void igt_suspend_signal_helper(void)
> +{
> + int status;
> +
> + if (!signal_helper.running)
> + return;
> +
> + kill(signal_helper.pid, SIGSTOP);
> + while (waitpid(signal_helper.pid, &status, WUNTRACED) == -1 &&
> + errno == EINTR)
> + ;
> +}
> +
> +/**
> + * igt_suspend_signal_helper:
> + *
> + * Resumes the child process spawned with igt_fork_signal_helper().
> + *
> + * This should be paired with igt_suspend_signal_helper() and called after the
> + * problematic code sensitive to signals.
> + */
> +void igt_resume_signal_helper(void)
> +{
> + if (!signal_helper.running)
> + return;
> +
> + kill(signal_helper.pid, SIGCONT);
> +}
> +
> static struct igt_helper_process shrink_helper;
> static void __attribute__((noreturn)) shrink_helper_process(int fd, pid_t pid)
> {
> diff --git a/lib/igt_aux.h b/lib/igt_aux.h
> index 499a1679..688ad1b8 100644
> --- a/lib/igt_aux.h
> +++ b/lib/igt_aux.h
> @@ -55,6 +55,8 @@ extern int num_trash_bos;
> /* generally useful helpers */
> void igt_fork_signal_helper(void);
> void igt_stop_signal_helper(void);
> +void igt_suspend_signal_helper(void);
> +void igt_resume_signal_helper(void);
>
> void igt_fork_shrink_helper(int fd);
> void igt_stop_shrink_helper(void);
> diff --git a/lib/igt_core.c b/lib/igt_core.c
> index 950ea9b0..ea4b5fa6 100644
> --- a/lib/igt_core.c
> +++ b/lib/igt_core.c
> @@ -2282,6 +2282,13 @@ int igt_system(const char *command)
> if (pipe(errpipe) < 0)
> goto err;
>
> + /*
> + * The clone() system call forking a large executable has difficulty
> + * to make progress if interrupted too frequently, so suspend it for
> + * the time of the syscall.
> + */
> + igt_suspend_signal_helper();
> +
> igt_fork_helper(&process) {
> close(outpipe[0]);
> close(errpipe[0]);
> @@ -2298,6 +2305,8 @@ int igt_system(const char *command)
> exit(EXIT_FAILURE);
> }
>
> + igt_resume_signal_helper();
> +
> close(outpipe[1]);
> close(errpipe[1]);
>
> --
> 2.13.2
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
