linux-kernel - Re: [PATCH v2 1/3] drm: Create an app info option for wedge events

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Message-ID: <x3ep3offdy5on6hckumvpsvnlfnmjdfqjlcyv7hojitzsn5u3k@opnou6grp7ad>
Date: Mon, 12 May 2025 06:08:59 +0000
From: Krzysztof Karas <krzysztof.karas@...el.com>
To: André Almeida <andrealmeid@...lia.com>
CC: Alex Deucher <alexander.deucher@....com>, Christian König
	<christian.koenig@....com>, <siqueira@...lia.com>, <airlied@...il.com>,
	<simona@...ll.ch>, Raag Jadav <raag.jadav@...el.com>,
	<rodrigo.vivi@...el.com>, <jani.nikula@...ux.intel.com>, Xaver Hugl
	<xaver.hugl@...il.com>, "Pierre-Loup A . Griffais"
	<pgriffais@...vesoftware.com>, <dri-devel@...ts.freedesktop.org>,
	<linux-kernel@...r.kernel.org>, <kernel-dev@...lia.com>,
	<amd-gfx@...ts.freedesktop.org>, <intel-xe@...ts.freedesktop.org>,
	<intel-gfx@...ts.freedesktop.org>
Subject: Re: [PATCH v2 1/3] drm: Create an app info option for wedge events

Hi André,

[...]

> @@ -582,6 +584,14 @@ int drm_dev_wedged_event(struct drm_device *dev, unsigned long method)
>  	drm_info(dev, "device wedged, %s\n", method == DRM_WEDGE_RECOVERY_NONE ?
>  		 "but recovered through reset" : "needs recovery");
>  
> +	if (info) {
> +		snprintf(pid_string, sizeof(pid_string), "PID=%u", info->pid);
> +		snprintf(comm_string, sizeof(comm_string), "APP=%s", info->comm);
> +	} else {
> +		snprintf(pid_string, sizeof(pid_string), "%s", "PID=-1");
> +		snprintf(comm_string, sizeof(comm_string), "%s", "APP=none");

I think using PID=-1 and APP=none might be misleading, because
something did cause the wedge if we landed here. You could use
"PID=unknown" and "APP=unknown" or ensure these arrays are
zeroed and fill them only if "info" is available:

-     char *envp[] = { event_string, NULL };
+     char pid_string[15] = {}, comm_string[TASK_COMM_LEN] = {};
+     char *envp[] = { event_string, pid_string, comm_string, NULL };

[...]

+     if (info) {
+             snprintf(pid_string, sizeof(pid_string), "PID=%u", info->pid);
+             snprintf(comm_string, sizeof(comm_string), "APP=%s", info->comm);
+     }

Then, when printing the logs later you could check if they have
a value and only use them if they do (or handle that however
you would see fit :) ).

Best Regards,
Krzysztof