From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Reinette Chatre <reinette.chatre@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Fenghua Yu <fenghua.yu@intel.com>, Borislav Petkov <bp@alien8.de>,
Tony Luck <tony.luck@intel.com>,
kuo-lang.tseng@intel.com, ravi.v.shankar@intel.com,
Ingo Molnar <mingo@redhat.com>, Babu Moger <babu.moger@amd.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH V5 4/4] x86/resctrl: Use appropriate API for strings terminated by newline
Date: Tue, 19 May 2020 19:07:10 +0300 [thread overview]
Message-ID: <20200519160710.GK1634618@smile.fi.intel.com> (raw)
In-Reply-To: <4a9603b8-32fb-024a-e2f5-14e95b4e3763@intel.com>
On Tue, May 19, 2020 at 08:50:22AM -0700, Reinette Chatre wrote:
> On 5/19/2020 1:28 AM, Andy Shevchenko wrote:
> > On Tue, May 19, 2020 at 2:50 AM Reinette Chatre
> > <reinette.chatre@intel.com> wrote:
...
> >> + ret = sysfs_match_string(rdt_mode_str, buf);
> >> + if (ret < 0) {
> >> + rdt_last_cmd_puts("Unknown or unsupported mode\n");
> >> + ret = -EINVAL;
> >> + goto out;
> >> + }
>
> From your previous email ...
>
> >> + ret = sysfs_match_string(rdt_mode_str, buf);
> >> + if (ret < 0) {
> >> + rdt_last_cmd_puts("Unknown or unsupported mode\n");
> >
> >> + ret = -EINVAL;
> >
> > This is redundant.
>
> I understand that shadowing an error code is generally of concern. In
> this case the error code is set to -EINVAL to ensure that it is the same
> error code that was returned to user space originally and will continue
> to be so no matter what changes may come to sysfs_match_string().
It returns -EINVAL and if that will be ever changed this driver would be one of
hundreds who suffers.
...
> > Can't we unify latter with a former like ...
> This would have been ideal if done from the start but currently "0" is
> returned if the current mode is pseudo-locked and user attempts to
> change the mode to pseudo-locked. Thus, to maintain the current user
> interface the check if user wants to set pseudo-locked mode is moved
> after the check if new mode is same as existing mode and thus not
> unified because that will result in an error returned always when user
> requests pseudo-locked mode.
Ah, I see now.
But we can then drop the check from sysfs_match_string() returned value, like
user_m = sysfs_match_string();
if (...) {
...
} else { // w/o even checking for the PSEUDO_LOCKED
...
goto out;
}
Can we?
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2020-05-19 16:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-18 23:46 [PATCH V5 0/4] x86/resctrl: Enable user to view and select thread throttling mode Reinette Chatre
2020-05-18 23:46 ` [PATCH V5 1/4] " Reinette Chatre
2020-05-18 23:46 ` [PATCH V5 2/4] x86/resctrl: Enumerate per-thread MBA Reinette Chatre
2020-05-18 23:46 ` [PATCH V5 3/4] x86/resctrl: Enable " Reinette Chatre
2020-05-18 23:46 ` [PATCH V5 4/4] x86/resctrl: Use appropriate API for strings terminated by newline Reinette Chatre
2020-05-19 8:19 ` Andy Shevchenko
2020-05-19 8:28 ` Andy Shevchenko
2020-05-19 15:50 ` Reinette Chatre
2020-05-19 16:07 ` Andy Shevchenko [this message]
2020-05-19 16:08 ` Andy Shevchenko
2020-05-19 17:54 ` Reinette Chatre
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