From: Rob Herring <robh@kernel.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Finn Thain <fthain@telegraphics.com.au>,
Stan Johnson <userm57@yahoo.com>
Cc: Frank Rowand <frowand.list@gmail.com>,
Chintan Pandya <cpandya@codeaurora.org>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: v4.17 regression: PowerMac G3 won't boot, was Re: [PATCH v5 1/3] of: cache phandle nodes to reduce cost of of_find_node_by_phandle()
Date: Mon, 10 Sep 2018 07:53:20 -0500 [thread overview]
Message-ID: <20180910125320.GA17028@bogus> (raw)
In-Reply-To: <7427daf6570d519e6793eb96d2fbaa52714b0cd7.camel@kernel.crashing.org>
On Sun, Sep 09, 2018 at 07:04:25PM +0200, Benjamin Herrenschmidt wrote:
> On Fri, 2018-08-31 at 14:58 +1000, Benjamin Herrenschmidt wrote:
> >
> > > A long shot, but something to consider, is that I failed to cover the
> > > cases of dynamic devicetree updates (removing nodes that contain a
> > > phandle) in ways other than overlays. Michael Ellerman has reported
> > > such a problem for powerpc/mobility with of_detach_node(). A patch to
> > > fix that is one of the tasks I need to complete.
> >
> > The only thing I can think of is booting via the BootX bootloader on
> > those ancient macs results in a DT with no phandles. I didn't see an
> > obvious reason why that would cause that patch to break though.
>
> Guys, we still don't have a fix for this one on its way upstream...
>
> My test patch just creates phandle properties for all nodes, that was
> not intended as a fix, more a way to check if the problem was related
> to the lack of phandles.
>
> I don't actually know why the new code causes things to fail when
> phandles are absent. This needs to be looked at.
>
> I'm travelling at the moment and generally caught up with other things,
> I haven't had a chance to dig, so just a heads up. I don't intend to
> submit my patch since it's just a band aid. We need to figure out what
> the actual problem is.
Can you try this patch (w/o Ben's patch). I think the problem is if
there are no phandles, then roundup_pow_of_two is passed 0 which is
documented as undefined result.
Though, if a DT has no properties with phandles, then why are we doing a
lookup in the first place?
8<----------------------------------------------------------------------
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 9095b8290150..74eaedd5b860 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -140,6 +140,9 @@ void of_populate_phandle_cache(void)
if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL)
phandles++;
+ if (!phandles)
+ goto out;
+
cache_entries = roundup_pow_of_two(phandles);
phandle_cache_mask = cache_entries - 1;
next prev parent reply other threads:[~2018-09-10 12:53 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-05 0:14 [PATCH v5 0/3] of: cache phandle nodes to reduce cost of of_find_node_by_phandle() frowand.list
2018-03-05 0:14 ` [PATCH v5 1/3] " frowand.list
2018-03-09 23:03 ` Rob Herring
2018-03-10 1:20 ` Frank Rowand
2018-06-12 18:16 ` Alan Tull
2018-06-13 14:42 ` Alan Tull
2018-06-13 21:47 ` Frank Rowand
2018-06-14 20:59 ` Alan Tull
2018-08-30 0:44 ` v4.17 regression: PowerMac G3 won't boot, was " Finn Thain
2018-08-30 1:05 ` Rob Herring
[not found] ` <569e4bc3-2149-4b2d-562f-e400dd05a8a8@yahoo.com>
2018-08-31 4:35 ` Benjamin Herrenschmidt
2018-08-31 4:49 ` Benjamin Herrenschmidt
2018-08-31 4:49 ` Benjamin Herrenschmidt
2018-08-31 4:36 ` Frank Rowand
2018-08-31 4:58 ` Benjamin Herrenschmidt
2018-09-09 17:04 ` Benjamin Herrenschmidt
2018-09-09 23:52 ` Frank Rowand
2018-09-10 12:53 ` Rob Herring [this message]
2018-09-11 15:53 ` Frank Rowand
[not found] ` <abb0dec2-da3a-2c04-0e9f-28851b22cf75@yahoo.com>
2018-09-12 0:15 ` Finn Thain
2018-03-05 0:14 ` [PATCH v5 2/3] memblock: add memblock_free() alloc when CONFIG_HAVE_MEMBLOCK is not set frowand.list
2018-03-06 0:00 ` Andrew Morton
2018-03-05 0:14 ` [PATCH v5 3/3] of: add early boot allocation of of_find_node_by_phandle() cache frowand.list
2018-03-05 20:26 ` Rob Herring
2018-03-06 3:12 ` Frank Rowand
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