linux-kernel - Re: [PATCH 2/3] selftests/resctrl: Simplify cleanup in ctrl-c handler

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Date: Tue, 20 Feb 2024 15:45:23 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
cc: Fenghua Yu <fenghua.yu@...el.com>, 
    Reinette Chatre <reinette.chatre@...el.com>, Shuah Khan <shuah@...nel.org>, 
    LKML <linux-kernel@...r.kernel.org>, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 2/3] selftests/resctrl: Simplify cleanup in ctrl-c
 handler

On Tue, 20 Feb 2024, Maciej Wieczor-Retman wrote:

> Ctrl-c handler isn't aware of what test is currently running. Because of
> that it executes all cleanups even if they aren't necessary. Since the
> ctrl-c handler uses the sigaction system no parameters can be passed
> to it as function arguments.
> 
> Add a global variable to make ctrl-c handler aware of the currently run
> test and only execute the correct cleanup callback.
> 
> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
> ---
>  tools/testing/selftests/resctrl/resctrl.h     |  2 ++
>  .../testing/selftests/resctrl/resctrl_tests.c | 20 +++++++++----------
>  tools/testing/selftests/resctrl/resctrl_val.c |  2 +-
>  3 files changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
> index 0f49df4961ea..79b45cbeb628 100644
> --- a/tools/testing/selftests/resctrl/resctrl.h
> +++ b/tools/testing/selftests/resctrl/resctrl.h
> @@ -128,6 +128,8 @@ extern pid_t bm_pid, ppid;
>  
>  extern char llc_occup_path[1024];
>  
> +extern struct resctrl_test current_test;

Why this is not just a pointer?

> +
>  int get_vendor(void);
>  bool check_resctrlfs_support(void);
>  int filter_dmesg(void);
> diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
> index 75fc49ba3efb..b17f7401892c 100644
> --- a/tools/testing/selftests/resctrl/resctrl_tests.c
> +++ b/tools/testing/selftests/resctrl/resctrl_tests.c
> @@ -14,6 +14,12 @@
>  static volatile int sink_target;
>  volatile int *value_sink = &sink_target;
>  
> +/*
> + * Set during test preparation for the cleanup function pointer used in
> + * ctrl-c sa_sigaction
> + */
> +struct resctrl_test current_test;
> +
>  static struct resctrl_test *resctrl_tests[] = {
>  	&mbm_test,
>  	&mba_test,
> @@ -75,18 +81,12 @@ static void cmd_help(void)
>  	printf("\t-h: help\n");
>  }
>  
> -void tests_cleanup(void)
> -{
> -	mbm_test_cleanup();
> -	mba_test_cleanup();
> -	cmt_test_cleanup();
> -	cat_test_cleanup();
> -}

This should be removed from resctrl.h too.

> -
> -static int test_prepare(void)
> +static int test_prepare(const struct resctrl_test *test)
>  {
>  	int res;
>  
> +	current_test = *test;

I'd prefer to keep this internal to signal handling functions so that 
either the struct resctrl_test or just the cleanup handler is passed 
to signal_handler_register().

It'd also allow current_test (or the cleanup function ptr) to be static.

-- 
 i.