[igt-dev] [PATCH i-g-t v2] igt/drv_module_reload: Revamp fault-injection

[Imre Deak]

On Wed, Jun 06, 2018 at 06:42:14PM +0100, Chris Wilson wrote:
> The current method of checking for a failed module load is flawed, as we
> only report the error on probing it is not being reported back by
> modprobe. So we have to dig inside the module_parameters while the
> module is still loaded to discover the error.
> 
> v2: Expect i915.inject_load_failure to be zero on success
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Michał Winiarski <michal.winiarski at intel.com>
> Cc: Imre Deak <imre.deak at intel.com>
> Reviewed-by: Michał Winiarski <michal.winiarski at intel.com>
> ---
>  tests/drv_module_reload.c | 45 ++++++++++++++++++++++++++++++++++-----
>  1 file changed, 40 insertions(+), 5 deletions(-)
> 
> diff --git a/tests/drv_module_reload.c b/tests/drv_module_reload.c
> index 092982960..e18aaea5e 100644
> --- a/tests/drv_module_reload.c
> +++ b/tests/drv_module_reload.c
> @@ -234,6 +234,38 @@ reload(const char *opts_i915)
>  	return err;
>  }
>  
> +static int open_parameters(const char *module_name)
> +{
> +	char path[256];
> +
> +	snprintf(path, sizeof(path), "/sys/module/%s/parameters", module_name);
> +	return open(path, O_RDONLY);
> +}
> +
> +static int
> +inject_fault(const char *module_name, const char *opt, int fault)
> +{
> +	char buf[1024];
> +	int dir;
> +
> +	igt_assert(fault > 0);
> +	snprintf(buf, sizeof(buf), "%s=%d", opt, fault);
> +
> +	if (igt_kmod_load(module_name, buf)) {
> +		igt_warn("Failed to load module '%s' with options '%s'\n",
> +			 module_name, buf);
> +		return 1;
> +	}
> +
> +	dir = open_parameters(module_name);
> +	igt_sysfs_scanf(dir, opt, "%d", &fault);

Just a note for later: in case we switch to async probing we'll have to
wait somehow until the probe completed. One way would be to disable
async probing for this test, not sure if that could hide some problem
though.

> +	close(dir);
> +
> +	igt_kmod_unload(module_name, 0);
> +
> +	return fault;
> +}
> +
>  static void
>  gem_sanitycheck(void)
>  {
> @@ -323,12 +355,15 @@ igt_main
>  		igt_assert_eq(reload("disable_display=1"), 0);
>  
>  	igt_subtest("basic-reload-inject") {
> -		char buf[64];
>  		int i = 0;
> -		do {
> -			snprintf(buf, sizeof(buf),
> -				 "inject_load_failure=%d", ++i);
> -		} while (reload(buf));
> +
> +		igt_i915_driver_unload();
> +
> +		while (inject_fault("i915", "inject_load_failure", ++i) == 0)
> +			;
> +
> +		/* We expect to hit at least one fault! */
> +		igt_assert(i > 1);
>  	}
>  
>  	igt_fixture {
> -- 
> 2.17.1
>