Re: [PATCH v4 07/19] selftests/resctrl: Refactor remount_resctrl(bool mum_resctrlfs) to mount_resctrl()

[Ilpo Järvinen]

On Thu, 13 Jul 2023, Reinette Chatre wrote:
> On 7/13/2023 6:19 AM, Ilpo Järvinen wrote:
> > Mount/umount of the resctrl FS is now paired nicely per test.
> > 
> > Rename remount_resctrl(bool mum_resctrlfs) to mount_resctrl(). Make
> > it unconditionally try to mount the resctrl FS and return error if
> > resctrl FS was mounted already.
> > 
> > While at it, group the mount/umount prototypes in the header.
> > 
> > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> > ---
> >  tools/testing/selftests/resctrl/resctrl.h     |  2 +-
> >  .../testing/selftests/resctrl/resctrl_tests.c |  8 ++++----
> >  tools/testing/selftests/resctrl/resctrlfs.c   | 20 +++++--------------
> >  3 files changed, 10 insertions(+), 20 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
> > index f455f0b7e314..23af3fb73cb4 100644
> > --- a/tools/testing/selftests/resctrl/resctrl.h
> > +++ b/tools/testing/selftests/resctrl/resctrl.h
> > @@ -85,8 +85,8 @@ extern char llc_occup_path[1024];
> >  int get_vendor(void);
> >  bool check_resctrlfs_support(void);
> >  int filter_dmesg(void);
> > -int remount_resctrlfs(bool mum_resctrlfs);
> >  int get_resource_id(int cpu_no, int *resource_id);
> > +int mount_resctrlfs(void);
> >  int umount_resctrlfs(void);
> >  int validate_bw_report_request(char *bw_report);
> >  bool validate_resctrl_feature_request(const char *resctrl_val);
> > diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
> > index a421d045de08..3f26d2279f75 100644
> > --- a/tools/testing/selftests/resctrl/resctrl_tests.c
> > +++ b/tools/testing/selftests/resctrl/resctrl_tests.c
> > @@ -77,7 +77,7 @@ static void run_mbm_test(bool has_ben, char **benchmark_cmd, int span,
> >  
> >  	ksft_print_msg("Starting MBM BW change ...\n");
> >  
> > -	res = remount_resctrlfs(true);
> > +	res = mount_resctrlfs();
> >  	if (res) {
> >  		ksft_exit_fail_msg("Failed to mount resctrl FS\n");
> >  		return;
> > @@ -106,7 +106,7 @@ static void run_mba_test(bool has_ben, char **benchmark_cmd, int span,
> >  
> >  	ksft_print_msg("Starting MBA Schemata change ...\n");
> >  
> > -	res = remount_resctrlfs(true);
> > +	res = mount_resctrlfs();
> >  	if (res) {
> >  		ksft_exit_fail_msg("Failed to mount resctrl FS\n");
> >  		return;
> > @@ -132,7 +132,7 @@ static void run_cmt_test(bool has_ben, char **benchmark_cmd, int cpu_no)
> >  
> >  	ksft_print_msg("Starting CMT test ...\n");
> >  
> > -	res = remount_resctrlfs(true);
> > +	res = mount_resctrlfs();
> >  	if (res) {
> >  		ksft_exit_fail_msg("Failed to mount resctrl FS\n");
> >  		return;
> > @@ -160,7 +160,7 @@ static void run_cat_test(int cpu_no, int no_of_bits)
> >  
> >  	ksft_print_msg("Starting CAT test ...\n");
> >  
> > -	res = remount_resctrlfs(true);
> > +	res = mount_resctrlfs();
> >  	if (res) {
> >  		ksft_exit_fail_msg("Failed to mount resctrl FS\n");
> >  		return;
> > diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
> > index b3a05488d360..f622245adafe 100644
> > --- a/tools/testing/selftests/resctrl/resctrlfs.c
> > +++ b/tools/testing/selftests/resctrl/resctrlfs.c
> > @@ -48,29 +48,19 @@ static int find_resctrl_mount(char *buffer)
> >  }
> >  
> >  /*
> > - * remount_resctrlfs - Remount resctrl FS at /sys/fs/resctrl
> > - * @mum_resctrlfs:	Should the resctrl FS be remounted?
> > + * mount_resctrlfs - Mount resctrl FS at /sys/fs/resctrl
> >   *
> >   * If not mounted, mount it.
> > - * If mounted and mum_resctrlfs then remount resctrl FS.
> > - * If mounted and !mum_resctrlfs then noop
> >   *
> >   * Return: 0 on success, non-zero on failure
> >   */
> 
> Since it is not obviously a "failure" I do think it will help to
> add to the comments that resctrl already being mounted is treated as
> a failure.
> 
> > -int remount_resctrlfs(bool mum_resctrlfs)
> > +int mount_resctrlfs(void)
> >  {
> > -	char mountpoint[256];
> >  	int ret;
> >  
> > -	ret = find_resctrl_mount(mountpoint);
> > -	if (ret)
> > -		strcpy(mountpoint, RESCTRL_PATH);
> > -
> > -	if (!ret && mum_resctrlfs && umount(mountpoint))
> > -		ksft_print_msg("Fail: unmounting \"%s\"\n", mountpoint);
> > -
> > -	if (!ret && !mum_resctrlfs)
> > -		return 0;
> > +	ret = find_resctrl_mount(NULL);
> > +	if (!ret)
> > +		return -1;
> 
> This treats "ret == 0" as a failure. What about -ENXIO? It seems to
> me that only "ret == -ENOENT" is "success".

Yes, it's a good catch.

-- 
 i.