Re: [PATCH 1/5] selftests/resctrl: Extend signal handler coverage to unmount on receiving signal

From: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
To: Reinette Chatre <reinette.chatre@intel.com>
Cc: "Shuah Khan" <shuah@kernel.org>,
	"Shuah Khan" <skhan@linuxfoundation.org>,
	linux-kselftest@vger.kernel.org,
	"Maciej Wieczór-Retman" <maciej.wieczor-retman@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"Shaopeng Tan" <tan.shaopeng@jp.fujitsu.com>,
	stable@vger.kernel.org
Subject: Re: [PATCH 1/5] selftests/resctrl: Extend signal handler coverage to unmount on receiving signal
Date: Wed, 13 Sep 2023 13:01:38 +0300 (EEST)	[thread overview]
Message-ID: <aab4b1cc-6eb5-c324-e97e-c6699e2d165@linux.intel.com> (raw)
In-Reply-To: <4176a620-4cec-5d57-42a3-a15c0fe3eb73@intel.com>

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On Tue, 12 Sep 2023, Reinette Chatre wrote:
> On 9/11/2023 4:19 AM, Ilpo Järvinen wrote:
> > Unmounting resctrl FS has been moved into the per test functions in
> > resctrl_tests.c by commit caddc0fbe495 ("selftests/resctrl: Move
> > resctrl FS mount/umount to higher level"). In case a signal (SIGINT,
> > SIGTERM, or SIGHUP) is received, the running selftest is aborted by
> > ctrlc_handler() which then unmounts resctrl fs before exiting. The
> > current section between signal_handler_register() and
> > signal_handler_unregister(), however, does not cover the entire
> > duration when resctrl FS is mounted.
> > 
> > Move signal_handler_register() and signal_handler_unregister() call
> > into the test functions in resctrl_tests.c to properly unmount resctrl
> > fs. Adjust child process kill() call in ctrlc_handler() to only be
> > invoked if the child was already forked.
> 
> Thank you for catching this.
> 
> > 
> > Fixes: caddc0fbe495 ("selftests/resctrl: Move resctrl FS mount/umount to higher level")
> > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> > Cc: <stable@vger.kernel.org>
> > ---
> >  tools/testing/selftests/resctrl/cat_test.c    |  8 -------
> >  .../testing/selftests/resctrl/resctrl_tests.c | 24 +++++++++++++++++++
> >  tools/testing/selftests/resctrl/resctrl_val.c | 22 ++++++++---------
> >  3 files changed, 34 insertions(+), 20 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
> > index 97b87285ab2a..224ba8544d8a 100644
> > --- a/tools/testing/selftests/resctrl/cat_test.c
> > +++ b/tools/testing/selftests/resctrl/cat_test.c
> > @@ -167,12 +167,6 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
> >  		strcpy(param.filename, RESULT_FILE_NAME1);
> >  		param.num_of_runs = 0;
> >  		param.cpu_no = sibling_cpu_no;
> > -	} else {
> > -		ret = signal_handler_register();
> > -		if (ret) {
> > -			kill(bm_pid, SIGKILL);
> > -			goto out;
> > -		}
> >  	}
> >  
> >  	remove(param.filename);
> > @@ -209,10 +203,8 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
> >  		}
> >  		close(pipefd[0]);
> >  		kill(bm_pid, SIGKILL);
> > -		signal_handler_unregister();
> >  	}
> >  
> > -out:
> >  	cat_test_cleanup();
> >  
> >  	return ret;
> > diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
> > index 823672a20a43..3d66fbdc2df3 100644
> > --- a/tools/testing/selftests/resctrl/resctrl_tests.c
> > +++ b/tools/testing/selftests/resctrl/resctrl_tests.c
> > @@ -73,8 +73,13 @@ static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no)
> >  
> >  	ksft_print_msg("Starting MBM BW change ...\n");
> >  
> > +	res = signal_handler_register();
> > +	if (res)
> > +		return;
> > +
> >  	res = mount_resctrlfs();
> >  	if (res) {
> > +		signal_handler_unregister();
> >  		ksft_exit_fail_msg("Failed to mount resctrl FS\n");
> >  		return;
> >  	}
> > @@ -91,6 +96,7 @@ static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no)
> >  
> >  umount:
> >  	umount_resctrlfs();
> > +	signal_handler_unregister();
> >  }
> >  
> >  static void run_mba_test(const char * const *benchmark_cmd, int cpu_no)
> > @@ -99,8 +105,13 @@ static void run_mba_test(const char * const *benchmark_cmd, int cpu_no)
> >  
> >  	ksft_print_msg("Starting MBA Schemata change ...\n");
> >  
> > +	res = signal_handler_register();
> > +	if (res)
> > +		return;
> > +
> >  	res = mount_resctrlfs();
> >  	if (res) {
> > +		signal_handler_unregister();
> >  		ksft_exit_fail_msg("Failed to mount resctrl FS\n");
> >  		return;
> >  	}
> > @@ -115,6 +126,7 @@ static void run_mba_test(const char * const *benchmark_cmd, int cpu_no)
> >  
> >  umount:
> >  	umount_resctrlfs();
> > +	signal_handler_unregister();
> >  }
> >  
> 
> This adds more duplicated code for every test. Have you considered a
> single test setup function that can be used to mount resctrl FS and setup
> the signal handler paired with a single test teardown function?

Yes. Consolidating all these is among my not-yet submitted patches.
I just had to do a backport-friendly Fixes patch first for this.

-- 
 i.