[LTP] [PATCH v1] libswap.c: Improve caculate swap dev number

[Wei Gao]

On Mon, Mar 04, 2024 at 06:04:08PM +0800, Li Wang wrote:
> On Mon, Mar 4, 2024 at 5:19 PM Yang Xu (Fujitsu) <xuyang2018.jy@fujitsu.com>
> wrote:
> 
> > Hi  Li，
> >
> > >
> > >
> > > On Sun, Mar 3, 2024 at 9:14 PM Petr Vorel <pvorel@suse.cz
> > > <mailto:pvorel@suse.cz>> wrote:
> > >
> > >     Hi Wei, Xu,
> > >
> > >      > Hi  Wei
> > >
> > >      > > I encounter a dead loop on following code in our test on ppc64
> > >     machine:
> > >      > > while ((c = fgetc(fp)) != EOF)
> > >
> > >      > > I think "/proc/swaps" is not normal file and can not get EOF in
> > >     some situation,
> > >      > > so i use fgets a line and caculate swap dev number.
> > >
> > >     I guess the problem has been fixed by another patch [1], thus
> > >     closing it in
> > >     patchwork. Please let me know if not.
> > >
> > >
> > > Seems not, the patch [1] below is mainly to count the free disk size.
> > >
> > > But Wei's work here is to calculate swap-dev numbers correctly
> > > (especially get rid of EOF affection to some degree).
> > >
> > > Xu Yang, what do you think? or did I miss anything here?
> > >
> > >
> >
> > I still think we can use the same way in ipc libs to get rid of the EOF
> > problem instead of
> > searching "dev" keyword. We just don't need to  calcualte "/proc/swaps"
> > header.
> >
> 
> Sounds good to me. At least it counts right lines.
> 
> It'd be great to have a patch by that way.
> 
> 
> 
> >
> > int get_used_sysvipc(const char *file, const int lineno, const char
> > *sysvipc_file)
> > {
> >         FILE *fp;
> >         int used = -1;
> >         char buf[BUFSIZE];
> >
> >         fp = safe_fopen(file, lineno, NULL, sysvipc_file, "r");
> >
> >         while (fgets(buf, BUFSIZE, fp) != NULL)
> >                 used++;
> >
> >         fclose(fp);
> >
> >         if (used < 0) {
> >                 tst_brk(TBROK, "can't read %s to get used sysvipc resource
> > total at "
> >                         "%s:%d", sysvipc_file, file, lineno);
> >         }
> >
> >         return used;
> > }
> >
> > But we don't get the actual reason, I still wonder why this deadloop
> > exists o ppcc64 instead of
> > other architecture(ie x86_64).
> >
> 
> Ok, I think we can just apply your suggested method to see if that deadloop
> disappears.
> 
Hi Petr, Xu, Li 
Deadloop will disappear if you use fgets, fgetc can not get EOF on ppc64.(Suspect an bug)
So either use my patch or Xu's suggestion both can work.

> 
> 
> -- 
> Regards,
> Li Wang
> 
> -- 
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