Re: [igt-dev] [PATCH v7 1/2] tests: Add a new test for driver/device hot reload

[Katarzyna Dec <katarzyna.dec@intel.com>]

On Thu, Apr 11, 2019 at 02:26:28PM +0200, Janusz Krzysztofik wrote:
> From: Janusz Krzysztofik <janusz.krzysztofik@intel.com>
> 
> Run a dummy load in background to put some workload on a device, then try
> to either remove (unplug) the device from its bus, or unbind the device's
> driver from it, depending on which subtest has been selected.  If
> succeeded, unload the driver, rescan the device's bus if needed and
> perform health checks on the device with the driver reloaded.
> 
> The dummy load is run from igt_fixture and in a sub-process, not directly
> from subtests,  as it is expected to fail and it's more simple to ignore
> igt_abort() in a sub-process.  Moreover, as soon as the sub-process fails
> and exits, resources it was using are freed automatically so there is no
> need to do any cleanups required for smooth module unload from the test
> level itself.  Those cleanups might also make the subtests fail if simply

> using igt library functions for that instead of reimplementing their safe
> parts only.
> 
> The driver hot unbind / device hot unplug operation is expected to succeed
> and the background workload sub-process to die in a reasonable time,
> however long timeouts are used to let kernel level timeouts pop up first
> if hit by a bug.
> 
> The dummy load works only on i915 driver.  The test is skipped on other
> hardware unless they provide their implementation of igt_spin_batch_new()
> and friends.
> 
There are few not needed spaces above, no need to send new version if this will
be the only thing (can be fixed during merging).
> Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@intel.com>
> ---
>  tests/Makefile.sources  |   1 +
>  tests/core_hot_reload.c | 256 ++++++++++++++++++++++++++++++++++++++++
>  tests/meson.build       |   1 +
>  3 files changed, 258 insertions(+)
>  create mode 100644 tests/core_hot_reload.c
> 
> diff --git a/tests/Makefile.sources b/tests/Makefile.sources
> index 214698da..d2c0941d 100644
> --- a/tests/Makefile.sources
> +++ b/tests/Makefile.sources
> @@ -16,6 +16,7 @@ TESTS_progs = \
>  	core_getclient \
>  	core_getstats \
>  	core_getversion \
> +	core_hot_reload \
>  	core_setmaster_vs_auth \
>  	debugfs_test \
>  	drm_import_export \
> diff --git a/tests/core_hot_reload.c b/tests/core_hot_reload.c
> new file mode 100644
> index 00000000..d862c99c
> --- /dev/null
> +++ b/tests/core_hot_reload.c
> @@ -0,0 +1,256 @@
> +/*
> + * Copyright © 2019 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#include "igt.h"
> +#include "igt_device.h"
> +#include "igt_dummyload.h"
> +#include "igt_kmod.h"
> +#include "igt_sysfs.h"
> +
> +#include <getopt.h>
> +#include <limits.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +
I think that 1 blank line will be fine.
> +typedef int (*action_t)(int dir);
> +typedef void (*workload_wait_t)(void *priv);
> +typedef void (*workload_t)(int device, const void *priv);
> +
> +
same here :)
> +/*
> + * Actions
> + *
> + * Purpose: make the device disappear
> + *
> + * @dir: file descriptor of an open device sysfs directory
> + *
> + * Return value: file descriptor of an open device bus' sysfs directory
> + * 		 or -1 if no bus rescan is needed
> + */
> +
I went though your answers on my quesions. It is more then ok to have a wider
overview on what is going on in whole binary, although I would prefer to have
some summary doc at the begining and small docs aboe functions (if needed).

> +/* Unbind the driver from the device */
> +static int driver_unbind(int dir)
> +{
> +	char path[PATH_MAX], *dev_bus_addr;
> +	int len;
> +
> +	len = readlinkat(dir, "device", path, sizeof(path) - 1);
> +	path[len] = '\0';
> +	dev_bus_addr = strrchr(path, '/') + 1;
> +
> +	igt_set_timeout(60, "Driver unbind timeout!");
> +	igt_sysfs_set(dir, "device/driver/unbind", dev_bus_addr);
> +
> +	/* No need for bus rescan */
> +	return -1;
> +}
> +
> +/* Remove (virtually unplug) the device from its bus */
> +static int device_unplug(int dir)
> +{
> +	int bus;
> +
> +	bus = openat(dir, "device/subsystem", O_DIRECTORY);
> +	igt_assert(bus >= 0);
> +
> +	igt_set_timeout(60, "Device unplug timeout!");
> +	igt_sysfs_set(dir, "device/remove", "1");
> +
> +	return bus;
> +}
> +
> +
> +/*
> + * Workloads
> + *
> + * Purpose: Put some long lasting load on the device
> + *
> + * @device: open device file descriptor,
> + * @priv: pointer to an optional argument passed to the workload
> + *
> + * Return value: none
> + */
> +
> +/* Workload using igt_spin_batch_run() */
> +
> +static void spin_batch(int device, const void *priv)
> +{
> +	igt_spin_t *spin;
> +
> +	/* submit the job */
> +	spin = igt_spin_batch_new(device);
> +
> +	/* wait for the job to crash */
> +	gem_sync(device, spin->handle);
> +
> +	/* clean up if still possible */
> +	igt_spin_batch_free(device, spin);
> +}
> +
> +
> +/*
> + * Skeleton
> + */
> +
> +static void healthcheck(int chipset)
> +{
> +	if (chipset == DRIVER_INTEL) {
> +		/*
> +		 * We have it perfectly implemented in i915_module_load,
> +		 * just use it.
> +		 */
> +		igt_assert(igt_system_quiet("i915_module_load --run-subtest reload")
> +			   == IGT_EXIT_SUCCESS);
> +	} else {
> +		/*
> +		 * We don't know how to check an unidentified device for health,
> +		 * device reopen must suffice.
> +		 */
> +	}
I saw you answer about this else and I agree that it is not for us to decide
what should code for other vendors look like. That is why we do not need else
here at all - healthcheck will be run only for INTEL + person who runs code will
not see any message that 'if' here was not hit.

The rest looks fine.
Kasia :)
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