linux-kernel - Re: Fwd: [PATCH v2 2/8] selftests/resctrl: Add basic resctrl file system operations and data

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Date:   Tue, 30 Oct 2018 11:35:45 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     Babu Moger <babu.moger@....com>, Fenghua Yu <fenghua.yu@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, H Peter Anvin <hpa@...or.com>,
        Tony Luck <tony.luck@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Reinette Chatre <reinette.chatre@...el.com>,
        James Morse <james.morse@....com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>,
        Arshiya Hayatkhan Pathan <arshiya.hayatkhan.pathan@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: Fwd: [PATCH v2 2/8] selftests/resctrl: Add basic resctrl file
 system operations and data

> From: Moger, Babu <Babu.Moger@....com>
> > From: Fenghua Yu <fenghua.yu@...el.com>
> > From: Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>
> >
> > The basic resctrl file system operations and data are added for future
> > usage by resctrl selftest tool.
> >
> > +     return 0;
> > +}
> > +
> > +char get_sock_num(int cpu_no)
> > +{
> > +     char sock_num, phys_pkg_path[1024];
> > +     FILE *fp;
> > +
> > +     sprintf(phys_pkg_path, "%s%d/topology/physical_package_id",
> > +             PHYS_ID_PATH, cpu_no);
> > +     fp = fopen(phys_pkg_path, "r");
> 
> There should corresponding fclose for this. In general, I would check all the
> fopens in this series. I found few of the files not closed while returning.
> More comments below.
> 
> > +     if (!fp || fscanf(fp, "%c", &sock_num) <= 0 || fclose(fp) == EOF) {

fclose is here.

> > +             perror("Could not get socket number");
> > +
> > +             return -1;
> > +     }
> > +
> > +      */
> > +     if (!freopen("/dev/null", "w", stdout))
> > +             PARENT_EXIT("Unable to direct BM op to /dev/null");
> 
> Do you need fclose for this before returning from this function?

This fclose is missing. I will add it.

> > +     /* Write child pid to con_mon grp */
> > +     fp = fopen(controlgroup, "w");
> 
> I don't see corresponding fclose.
> 
> > +     if (!fp || fprintf(fp, "%d\n", bm_pid) <= 0 || fclose(fp) == EOF) {

fclose is here:)

> > +             perror("Failed to write child to con_mon grp");
> > +
> > +             return errno;
> > +     }
> > +
> > +     /* Write child pid to mon grp, only for "mbm" */
> > +     if ((strcmp(resctrl_val, "mbm") == 0)) {
> > +             if (mongrp) {
> > +                     fp = fopen(monitorgroup, "w");
> > +                     if (!fp || fprintf(fp, "%d\n", bm_pid) <= 0 ||
> > +                         fclose(fp) == EOF) {
> 
> 
> I feel too many checks at one place.  If fprintf fails,  will it fclose the
> file? I suggest to separate these checks.

You are right. I will separate the checks in multiple lines.

> 
> > +
> > +             fp = fopen(controlgroup, "w");
> > +             if (!fp || fprintf(fp, "%s\n", schema) <= 0 ||
> > +                 fclose(fp) == EOF) {
> 
> Same comment as above.. If fprintf fails,  will it fclose the file? I suggest
> to separate these checks.

Sure.

I will change code based on your comments.

Thanks.

-Fenghua