Re: [RFC PATCH i-g-t] lib: Add warning if lockdep is disabled before a test.

From: Daniel Vetter <daniel@ffwll.ch>
To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Intel Graphics Development <intel-gfx@lists.freedesktop.org>
Subject: Re: [RFC PATCH i-g-t] lib: Add warning if lockdep is disabled before a test.
Date: Wed, 20 Apr 2016 16:17:35 +0200	[thread overview]
Message-ID: <20160420141735.GL2510@phenom.ffwll.local> (raw)
In-Reply-To: <57162EC6.7070709@linux.intel.com>

On Tue, Apr 19, 2016 at 03:12:38PM +0200, Maarten Lankhorst wrote:
> When running tests, it will produce warnings like this:
> 
> (core_auth:2552) igt-core-WARNING: Lockdep is turned off.
> 
> This makes sure lockdep warnings during load aren't accidentally ignored.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

Ack on the idea.
-Daniel

> ---
> Unfortunately this version suffers from a small problem, piglit still succeeds without WARN. :(
> 
> Seems to be an issue in piglit/tests/igt.py that needs a separate fix.
> 
> diff --git a/lib/igt_core.c b/lib/igt_core.c
> index 832361b0a9f9..bb17ddfbcadb 100644
> --- a/lib/igt_core.c
> +++ b/lib/igt_core.c
> @@ -570,6 +570,39 @@ static void oom_adjust_for_doom(void)
>  
>  }
>  
> +static void igt_warn_lockdep(void)
> +{
> +	FILE *f;
> +	long val;
> +	char line[256];
> +
> +	f = fopen("/proc/lockdep_stats", "r");
> +	if (!f && errno == ENOENT) {
> +		igt_debug("Lockdep is not compiled in.\n");
> +		return;
> +	}
> +
> +	igt_assert(f);
> +
> +	while (fgets(line, sizeof(line), f)) {
> +		if (strncmp(line, " debug_locks:", 13))
> +			continue;
> +
> +		val = strtol(line + 13, NULL, 10);
> +
> +		if (!val)
> +			igt_warn("Lockdep is turned off.\n");
> +		else
> +			igt_debug("Lockdep is active.\n");
> +		goto out;
> +	}
> +
> +	igt_warn("Could not find lockdep setting.\n");
> +
> +out:
> +	fclose(f);
> +}
> +
>  static int common_init(int *argc, char **argv,
>  		       const char *extra_short_opts,
>  		       const struct option *extra_long_opts,
> @@ -741,6 +774,8 @@ out:
>  		low_mem_killer_disable(true);
>  	}
>  
> +	igt_warn_lockdep();
> +
>  	/* install exit handler, to ensure we clean up */
>  	igt_install_exit_handler(common_exit_handler);
>  
> 
> _______________________________________________
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> Intel-gfx@lists.freedesktop.org
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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