Re: [igt-dev] [Intel-gfx] [PATCH i-g-t] tests/i915_suspend: Free device list after *-without-i915 subtests

[Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>]

On Monday, 13 February 2023 10:51:39 CET Zbigniew Kempczyński wrote:
> On Fri, Feb 10, 2023 at 10:33:21PM +0100, Janusz Krzysztofik wrote:
> > On Thursday, 9 February 2023 20:32:31 CET Janusz Krzysztofik wrote:
> > > If any of *-without-i915 subtests fails or skips for any reason, it may
> > > leave the i915 module unloaded while keeping our device list populated
> > > with initially collected data.  In a follow up igt_fixture section we 
then
> > > try to reopen the device.  If the test has been executed with a device
> > > filter specified, an attempt to open the device finds a matching entry
> > > that belongs to the no longer existing device in that initially 
collected
> > > device list, fails to stat() it, concludes that's because of the device
> > > having been already open, and returns an error.
> > > 
> > > Fix this potentially confusing test result by freeing the potentially
> > > outdated device list before continuing with drm_open_driver().
> > 
> > Freeing device list occurred not safe if device scan was not performed 
before.  
> > I can see 3 potential solutions:
> > 1) force device rescan instead of free before calling drm_open_driver(),
> > 2) teach igt_device_free() to return immediately if the device list has 
not 
> >    been allocated,
> > 3) provide a has_device_list() helper for to be used if not sure before 
> >    calling igt_device_free().
> > 
> > Any preferences?
> 
> I would enforce rescan.
> 
> BTW I wonder how it can happen if runner is executing each subtest
> in new process so you're starting from scratch and rescan should be
> executed automatically.

The scenario I'm trying to address is different: a subtest fails, leaving the 
i915 module unloaded but the device list populated.  Then, before the test 
exist, open_drm_driver() called from a follow up igt_fixture section falsely 
detects the (non-existent) device as already open and fails instead of 
reloading the module.

While that late failure shouldn't affect results of the subtest, debug 
messages triggered from that failed device_open_driver() can occur potentially 
misleading to anyone watching CI results, then should be avoided if possible.

Thanks,
Janusz


> 
> Is is the case you're running few tests from the console?
> 
> --
> Zbigniew
> 
> 
> > 
> > Thanks,
> > Janusz
> > 
> > > 
> > > While being at it, add a comment that explains why we call
> > > igt_device_scan() from __igt_device_card_match() but don't force device
> > > rescan, and emit a debug message if we fail in _is_already_opened() on
> > > unsuccessful device stat().
> > > 
> > > Subtest basic-s3-without-i915: FAIL (9.572s)
> > > (i915_suspend:9050) drmtest-WARNING: card maching filter 0 is already 
opened
> > > (i915_suspend:9050) drmtest-CRITICAL: Test abort in function 
drm_open_driver, file ../lib/drmtest.c:639:
> > > (i915_suspend:9050) drmtest-CRITICAL: abort condition: fd < 0
> > > (i915_suspend:9050) drmtest-CRITICAL: Last errno: 2, No such file or 
directory
> > > (i915_suspend:9050) drmtest-CRITICAL: No known gpu found for chipset 
flags 0x1 (intel)
> > > Test i915_suspend failed.
> > > **** DEBUG ****
> > > (i915_suspend:9050) drmtest-DEBUG: Looking for devices to open using 
filter 0: pci:vendor=intel,device=dg2
> > > (i915_suspend:9050) drmtest-DEBUG: Filter matched /dev/dri/card0 | /dev/
dri/renderD128
> > > (i915_suspend:9050) drmtest-WARNING: card maching filter 0 is already 
opened
> > > (i915_suspend:9050) drmtest-CRITICAL: Test abort in function 
drm_open_driver, file ../lib/drmtest.c:639:
> > > (i915_suspend:9050) drmtest-CRITICAL: abort condition: fd < 0
> > > (i915_suspend:9050) drmtest-CRITICAL: Last errno: 2, No such file or 
directory
> > > (i915_suspend:9050) drmtest-CRITICAL: No known gpu found for chipset 
flags 0x1 (intel)
> > > (i915_suspend:9050) igt_core-INFO: Stack trace:
> > > (i915_suspend:9050) igt_core-INFO:   #0 ../lib/igt_core.c:2066 
__igt_abort()
> > > (i915_suspend:9050) igt_core-INFO:   #1 ../lib/drmtest.c:573 
drm_open_driver()
> > > (i915_suspend:9050) igt_core-INFO:   #2 ../tests/i915/i915_suspend.c:258 
__igt_unique____real_main245()
> > > (i915_suspend:9050) igt_core-INFO:   #3 ../tests/i915/i915_suspend.c:245 
main()
> > > (i915_suspend:9050) igt_core-INFO:   #4 ../sysdeps/nptl/
libc_start_call_main.h:58 __libc_start_call_main()
> > > (i915_suspend:9050) igt_core-INFO:   #5 ../csu/libc-start.c:128 
__libc_start_main@@GLIBC_2.34()
> > > (i915_suspend:9050) igt_core-INFO:   #6 [_start+0x2a]
> > > ****  END  ****
> > > 
> > > Fixes: f7aff600ab16 ("tests/i915/i915_suspend: Disable d3cold_allowed 
for basic-s2idle-without-i915")
> > > Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
> > > Cc: Riana Tauro <riana.tauro@intel.com>
> > > ---
> > >  lib/drmtest.c             |  2 +-
> > >  lib/igt_device_scan.c     |  4 ++++
> > >  tests/i915/i915_suspend.c | 10 +++++++++-
> > >  3 files changed, 14 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/lib/drmtest.c b/lib/drmtest.c
> > > index 16e80bdfcf..8e2d1ac50b 100644
> > > --- a/lib/drmtest.c
> > > +++ b/lib/drmtest.c
> > > @@ -260,7 +260,7 @@ static bool _is_already_opened(const char *path, int 
as_idx)
> > >  	 * we cannot even stat the device, so it's of no use - let's claim 
it's
> > >  	 * already opened
> > >  	 */
> > > -	if (stat(path, &new) != 0)
> > > +	if (igt_debug_on(stat(path, &new) != 0))
> > >  		return true;
> > >  
> > >  	for (int i = 0; i < as_idx; ++i) {
> > > diff --git a/lib/igt_device_scan.c b/lib/igt_device_scan.c
> > > index 8b767eed20..ae69ed09f1 100644
> > > --- a/lib/igt_device_scan.c
> > > +++ b/lib/igt_device_scan.c
> > > @@ -1918,6 +1918,10 @@ static bool __igt_device_card_match(const char 
*filter,
> > >  		return false;
> > >  	memset(card, 0, sizeof(*card));
> > >  
> > > +	/*
> > > +	 * Scan devices in case the user hasn't yet,
> > > +	 * but leave a decision on forced rescan on the user side.
> > > +	 */
> > >  	igt_devices_scan(false);
> > >  
> > >  	if (igt_device_filter_apply(filter) == false)
> > > diff --git a/tests/i915/i915_suspend.c b/tests/i915/i915_suspend.c
> > > index 815f1c8a2c..c68110476e 100644
> > > --- a/tests/i915/i915_suspend.c
> > > +++ b/tests/i915/i915_suspend.c
> > > @@ -253,8 +253,16 @@ igt_main
> > >  	igt_subtest("basic-s3-without-i915")
> > >  		test_suspend_without_i915(SUSPEND_STATE_S3);
> > >  
> > > -	igt_fixture
> > > +	igt_fixture {
> > > +		/*
> > > +		 * Since above tests may fail leaving the i915 module 
unloaded,
> > > +		 * force refresh of device list before opening an i915 
device
> > > +		 * by cleaning up the current device list, otherwise we 
can fail
> > > +		 * if we have been called with a device filter 
specified.
> > > +		 */
> > > +		igt_devices_free();
> > >  		fd = drm_open_driver(DRIVER_INTEL);
> > > +	}
> > >  
> > >  	igt_subtest("fence-restore-tiled2untiled") {
> > >  		gem_require_mappable_ggtt(fd);
> > > 
> > 
> > 
> > 
> > 
>