[LTP] [PATCH v2] mem/hugetlb: shift an empty region to use in hugemmap02.c

[Li Wang]

Hi,

On Tue, Oct 13, 2015 at 2:29 AM, Cyril Hrubis <chrubis@suse.cz> wrote:

> Hi!
> Generall idea looks good, a few comments below.
>
> > +/* MMAP */
> > +int range_is_mapped(unsigned long low, unsigned long high)
> >  #endif
> > diff --git a/testcases/kernel/mem/lib/mem.c
> b/testcases/kernel/mem/lib/mem.c
> > index 118b6c0..e0e1bdf 100644
> > --- a/testcases/kernel/mem/lib/mem.c
> > +++ b/testcases/kernel/mem/lib/mem.c
> > @@ -1113,3 +1113,46 @@ void update_shm_size(size_t * shm_size)
> >               *shm_size = shmmax;
> >       }
> >  }
> > +
> > +int range_is_mapped(unsigned long low, unsigned long high)
> > +{
> > +     FILE *f;
> > +     int MAPS_BUF_SZ = 4096;
> > +     char line[MAPS_BUF_SZ];
> > +     char *tmp;
> > +
> > +     f = fopen("/proc/self/maps", "r");
> > +     if (!f) {
> > +             printf("Failed to open /proc/self/maps.\n");
>                 ^
>                 should rather be tst_resm(TWARN, );
>

ok. looks like using
    FILE * f = SAFE_FOPEN(NULL, "/proc/self/maps", "r");
is better than above.


> > +             return -1;
> > +     }
> > +
> > +     while (1) {
> > +             unsigned long start, end;
> > +             int ret;
> > +
> > +             tmp = fgets(line, MAPS_BUF_SZ, f);
> > +             if (!tmp)
> > +                     break;
> > +
> > +             ret = sscanf(line, "%lx-%lx", &start, &end);
> > +             if (ret != 2) {
> > +                     printf("Couldn't parse /proc/self/maps line: %s\n",
> > +                                     line);
>                         ^
>                         here as well
>

ok.


> > +                     fclose(f);
> > +                     return -1;
> > +             }
>
> Why don't you just use fscanf()? It doesn't make sense to read the line
> into the buffer and then sscanf() the values.
>

hmm, we need to read the '/proc/self/maps' line by line, It easy to use fgets()
to get each line in and then sscanf() that.

fscanf() will never read the newline at the end of the first line. So when
it is called the second time, it will fail (returning 0, not EOF) and read
nothing, leaving the [start, end] unchanged.
maybe I don't know if fscanf() could achieve that also?

so what about something like:
--------------------------------------
int range_is_mapped(unsigned long low, unsigned long high)
{
    FILE *f = SAFE_FOPEN(NULL, "/proc/self/maps", "r");

    int MAPS_BUF_SZ = 4096;
    char line[MAPS_BUF_SZ];

    while (fgets(line, MAPS_BUF_SZ, f)) {
        unsigned long start, end;
        int ret;

        ret = sscanf(line, "%lx-%lx", &start, &end);
        if (ret != 2) {
            tst_resm(TWARN | TERRNO, "Couldn't parse /proc/self/maps
line.");
            SAFE_FCLOSE(NULL, f);
        }

        if ((start >= low) && (start < high)) {
            SAFE_FCLOSE(NULL, f);
            return 1;
        }
        if ((end >= low) && (end < high)) {
            SAFE_FCLOSE(NULL, f);
            return 1;
        }
    }

    SAFE_FCLOSE(NULL, f);
    return 0;
}



> > +             if ((start >= low) && (start < high)) {
> > +                     fclose(f);
> > +                     return 1;
> > +             }
> > +             if ((end >= low) && (end < high)) {
> > +                     fclose(f);
> > +                     return 1;
> > +             }
> > +     }
> > +
> > +     fclose(f);
> > +     return 0;
> > +}
>
> --
> Cyril Hrubis
> chrubis@suse.cz
>



-- 
Regards,
Li Wang
Email: liwang@redhat.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.linux.it/pipermail/ltp/attachments/20151013/95af04a5/attachment-0001.html>