[igt-dev] [PATCH i-g-t v3 6/6] lib/igt_kmod: properly handle pipewire-pulse

[Andi Shyti]

Hi Mauro,

> +static void pipewire_reserve_wait(int pipewire_pulse_pid)
> +{
> +	char xdg_dir[PATH_MAX];
> +	const char *homedir;
> +	struct passwd *pw;
> +	proc_t *proc_info;
> +	PROCTAB *proc;
> +
> +	igt_fork(child, 1) {
> +		igt_info("Preventing pipewire-pulse to use the audio drivers\n");
> +
> +		proc = openproc(PROC_FILLCOM | PROC_FILLSTAT | PROC_FILLARG);
> +		igt_assert(proc != NULL);
> +
> +		while ((proc_info = readproc(proc, NULL))) {
> +			if (pipewire_pulse_pid == proc_info->tid)
> +				break;
> +			freeproc(proc_info);
> +		}
> +		closeproc(proc);
> +
> +		/* Sanity check: if it can't find the process, it means it has gone */
> +		if (pipewire_pulse_pid != proc_info->tid)
> +			exit(0);
> +
> +		pw = getpwuid(proc_info->euid);
> +		homedir = pw->pw_dir;
> +		snprintf(xdg_dir, sizeof(xdg_dir), "/run/user/%d", proc_info->euid);
> +		setgid(proc_info->egid);
> +		setuid(proc_info->euid);
> +		clearenv();
> +		setenv("HOME", homedir, 1);
> +		setenv("XDG_RUNTIME_DIR",xdg_dir, 1);
> +		freeproc(proc_info);
> +
> +		exit(system("pw-reserve -n Audio0 -r"));

no exit...

> +	}

... and waitchild().

Like in patch 1 :)

> +}
> +
> +static int pipewire_pw_reserve_pid = 0;
> +
> +/* Maximum time waiting for pw-reserve to start running */
> +#define PIPEWIRE_RESERVE_MAX_TIME 1000 /* milisseconds */
> +
> +int pipewire_pulse_start_reserve(int pipewire_pulse_pid)
> +{
> +	bool is_pw_reserve_running = false;
> +	proc_t *proc_info;
> +	int attempts = 0;
> +	PROCTAB *proc;
> +
> +	if (!pipewire_pulse_pid)
> +		return 0;
> +
> +	pipewire_reserve_wait(pipewire_pulse_pid);
> +
> +	/*
> +	 * Note: using pw-reserve to stop using audio only works with
> +	 * pipewire version 0.3.50 or upper.
> +	 */
> +	for (attempts = 0; attempts < PIPEWIRE_RESERVE_MAX_TIME; attempts++) {
> +		usleep(1000);
> +		proc = openproc(PROC_FILLCOM | PROC_FILLSTAT | PROC_FILLARG);
> +		igt_assert(proc != NULL);
> +
> +		while ((proc_info = readproc(proc, NULL))) {
> +			if (!strcmp(proc_info->cmd, "pw-reserve")) {
> +				is_pw_reserve_running = true;
> +				pipewire_pw_reserve_pid = proc_info->tid;
> +				freeproc(proc_info);
> +				break;
> +			}
> +			freeproc(proc_info);
> +		}
> +		closeproc(proc);
> +		if (is_pw_reserve_running)
> +			break;
> +	}
> +	if (!is_pw_reserve_running) {
> +		igt_warn("Failed to remove audio drivers from pipewire\n");
> +		return 1;
> +	}
> +	/* Let's grant some time for pw_reserve to notify pipewire via D-BUS */
> +	usleep(50000);
> +
> +	/*
> +	 * pw-reserve is running, and should have stopped using the audio
> +	 * drivers. We can now remove the driver.
> +	 */
> +
> +	return 0;
> +}
> +
> +void pipewire_pulse_stop_reserve(int pipewire_pulse_pid)
> +{
> +	if (!pipewire_pulse_pid)
> +		return;
> +
> +	igt_killchildren(SIGTERM);

why do we need the sigterm? I guess here you need to modify
kill_children so that it kills with a signal. Otherwise this
SIGTERM is useless.

>  /**
>   * __igt_lsof_audio_and_kill_proc() - check if a given process is using an
>   *	audio device. If so, stop or prevent them to use such devices.
>   *
>   * @proc_info: process struct, as returned by readproc()
>   * @proc_path: path of the process under procfs
> + * @pipewire_pulse_pid: PID of pipewire-pulse process
>   *
>   * No processes can be using an audio device by the time it gets removed.
>   * This function checks if a process is using an audio device from /dev/snd.
> @@ -1448,10 +1550,15 @@ static void pulseaudio_unload_module(proc_t *proc_info)
>   * 	- if the process is pulseaudio, it can't be killed, as systemd will
>   * 	  respawn it. So, instead, send a request for it to stop bind the
>   * 	  audio devices.
> + *	- if the process is pipewire-pulse, it can't be killed, as systemd will
> + *	  respawn it. So, instead, the caller should call pw-reserve, remove
> + *	  the kernel driver and then stop pw-reserve. On such case, this
> + *	  function returns the PID of pipewire-pulse, but won't touch it.
>   * If the check fails, it means that the process can simply be killed.
>   */
>  static int
> -__igt_lsof_audio_and_kill_proc(proc_t *proc_info, char *proc_path)
> +__igt_lsof_audio_and_kill_proc(proc_t *proc_info, char *proc_path,
> +			       int *pipewire_pulse_pid)

Still I think that this is becoming messy. We are carrying this
pipewire_pulse_pid from function to function with a possible
value of '0'.

Anyway, I will not insist on this.

[...]

> +void igt_killchildren(int signal)
> +{
> +	igt_info("Timed out waiting for children\n");
> +
> +	kill_children();
> +}

As I said before, we don't really need for int signal. And I
think this should in a different patch as this is a change in
igt_core?

Andi