Messages in this thread Patch in this message | | | From | Geert Uytterhoeven <> | Date | Thu, 26 Mar 2020 09:21:55 +0100 | Subject | Re: [PATCH 2/2] of: some unittest overlays not untracked |
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Hi Frank,
On Thu, Mar 26, 2020 at 2:47 AM <frowand.list@gmail.com> wrote: > From: Frank Rowand <frank.rowand@sony.com> > > kernel test robot reported "WARNING: held lock freed!" triggered by > unittest_gpio_remove(), which should not have been called because > the related gpio overlay was not tracked. Another overlay that > was tracked had previously used the same id as the gpio overlay > but had not been untracked when the overlay was removed. Thus the > clean up function of_unittest_destroy_tracked_overlays() incorrectly > attempted to remove the reused overlay id. > > Patch contents: > > - Create tracking related helper functions > - Change BUG() to WARN_ON() for overlay id related issues > - Add some additional error checking for valid overlay id values > - Add the missing overlay untrack > - update comment on expectation that overlay ids are assigned in > sequence > > Fixes: 492a22aceb75 ("of: unittest: overlay: Keep track of created overlays") > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Looks good to me, so: Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Still, a few suggestions for future improvement below...
> --- a/drivers/of/unittest.c > +++ b/drivers/of/unittest.c > @@ -1689,19 +1689,27 @@ static const char *overlay_name_from_nr(int nr) > > static const char *bus_path = "/testcase-data/overlay-node/test-bus"; > > -/* it is guaranteed that overlay ids are assigned in sequence */ > +/* FIXME: it is NOT guaranteed that overlay ids are assigned in sequence */ > + > #define MAX_UNITTEST_OVERLAYS 256 > static unsigned long overlay_id_bits[BITS_TO_LONGS(MAX_UNITTEST_OVERLAYS)];
Obviously this should have used DECLARE_BITMAP() ;-)
> static int overlay_first_id = -1; > > +static long of_unittest_overlay_tracked(int id) > +{ > + if (WARN_ON(id >= MAX_UNITTEST_OVERLAYS)) > + return 0;
Do we need all these checks on id? Can this really happen? I guess doing it once in of_unittest_track_overlay(), and aborting all of_unittests if it triggers should be sufficient?
> + return overlay_id_bits[BIT_WORD(id)] & BIT_MASK(id);
No need for BIT_{WORD,MASK}() calculations if you would use test_bit().
> +} > + > static void of_unittest_track_overlay(int id) > { > if (overlay_first_id < 0) > overlay_first_id = id; > id -= overlay_first_id; > > - /* we shouldn't need that many */ > - BUG_ON(id >= MAX_UNITTEST_OVERLAYS); > + if (WARN_ON(id >= MAX_UNITTEST_OVERLAYS)) > + return; > overlay_id_bits[BIT_WORD(id)] |= BIT_MASK(id);
set_bit()
> } > > @@ -1710,7 +1718,8 @@ static void of_unittest_untrack_overlay(int id) > if (overlay_first_id < 0) > return; > id -= overlay_first_id; > - BUG_ON(id >= MAX_UNITTEST_OVERLAYS); > + if (WARN_ON(id >= MAX_UNITTEST_OVERLAYS)) > + return; > overlay_id_bits[BIT_WORD(id)] &= ~BIT_MASK(id);
clear_bit()
> } > > @@ -1726,7 +1735,7 @@ static void of_unittest_destroy_tracked_overlays(void) > defers = 0; > /* remove in reverse order */
If it is not guaranteed that overlay ids are assigned in sequence, the reverse order is not really needed, so you could replace the bitmap and your own tracking mechanism by DEFINE_IDR() and idr_for_each()? And as IDRs are flexible, MAX_UNITTEST_OVERLAYS and all checks could be removed, too.
> for (id = MAX_UNITTEST_OVERLAYS - 1; id >= 0; id--) { > - if (!(overlay_id_bits[BIT_WORD(id)] & BIT_MASK(id))) > + if (!of_unittest_overlay_tracked(id)) > continue; > > ovcs_id = id + overlay_first_id; > @@ -1743,7 +1752,7 @@ static void of_unittest_destroy_tracked_overlays(void) > continue; > } > > - overlay_id_bits[BIT_WORD(id)] &= ~BIT_MASK(id); > + of_unittest_untrack_overlay(id); > } > } while (defers > 0); > }
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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