Messages in this thread | | | Date | Fri, 30 Jan 2015 10:00:23 +0100 | Subject | Re: [1/3] powerpc/pmac: Fix DT refcount imbalance in pmac_pic_probe_oldstyle | From | Geert Uytterhoeven <> |
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Hi Michael,
On Fri, Jan 30, 2015 at 5:09 AM, Michael Ellerman <mpe@ellerman.id.au> wrote: > On Wed, 2015-14-01 at 13:51:57 UTC, Geert Uytterhoeven wrote: >> of_find_node_by_name() calls of_node_put() on its "from" parameter, >> which must not be done on "master", as it's still in use, and will be >> released manually later. This may cause a zero kref refcount. >> Use of_get_child_by_name() instead to fix this. > > But of_find_node_by_name() searches *all* nodes, not just the children of the > parameter.
That's correct. However, I guess the second mac-io will just be a direct child.
> So this is a logic change AFAICS, and I have no idea what machines we'd need to > test on to check it.
Originally it comes from arch/ppc/platforms/pmac_pic.c, added in 2002 in full-history-linux commit 5ea3254844ae344a ("Import arch/ppc and include/asm-ppc changes from linuxppc_2_5 tree").
I've also checked my linuxppc mail archives from 1997-2002, but couldn't find the actual patch and a description.
So I don't know on which machines it's needed.
> So I think an of_node_get(master) would be safer and also fix the refcounting.
If no one can confirm the above, that may indeed be the best solution.
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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