commit e54192b48da75f025ae4b277925eaf6aca1d13bd
author Rob Herring <robh@kernel.org> Tue Sep 11 09:28:14 2018 -0500
committer Rob Herring <robh@kernel.org> Tue Sep 11 11:28:40 2018 -0500
tree f31ac5662c779ae66b72c91dcaf3be22087daeca
parent 0413bedabc886c3a56804d1c80a58e99077b1d91

of: fix phandle cache creation for DTs with no phandles

With commit 0b3ce78e90fc ("of: cache phandle nodes to reduce cost of
of_find_node_by_phandle()"), a G3 PowerMac fails to boot. The root cause
is the DT for this system has no phandle properties when booted with
BootX. of_populate_phandle_cache() does not handle the case of no
phandles correctly. The problem is roundup_pow_of_two() for 0 is
undefined. The implementation subtracts 1 underflowing and then things
are in the weeds.

Fixes: 0b3ce78e90fc ("of: cache phandle nodes to reduce cost of of_find_node_by_phandle()")
Cc: stable@vger.kernel.org # 4.17+
Reported-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Reviewed-by: Frank Rowand <frank.rowand@sony.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Rob Herring <robh@kernel.org>