* [PATCH] of: fix phandle cache creation for DTs with no phandles
@ 2018-09-11 14:56 Rob Herring
2018-09-11 16:02 ` Frank Rowand
0 siblings, 1 reply; 2+ messages in thread
From: Rob Herring @ 2018-09-11 14:56 UTC (permalink / raw)
To: Finn Thain, Stan Johnson, Frank Rowand, Benjamin Herrenschmidt
Cc: devicetree, linux-kernel, linuxppc-dev, stable
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>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Rob Herring <robh@kernel.org>
---
Here's a formal patch of what Stan tested. Will send to Linus this week.
Rob
drivers/of/base.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index a055cd1ef96d..17ae594b7014 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;
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] of: fix phandle cache creation for DTs with no phandles
2018-09-11 14:56 [PATCH] of: fix phandle cache creation for DTs with no phandles Rob Herring
@ 2018-09-11 16:02 ` Frank Rowand
0 siblings, 0 replies; 2+ messages in thread
From: Frank Rowand @ 2018-09-11 16:02 UTC (permalink / raw)
To: Rob Herring, Finn Thain, Stan Johnson, Benjamin Herrenschmidt
Cc: devicetree, linux-kernel, linuxppc-dev, stable
On 09/11/18 07:56, Rob Herring wrote:
> 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>
> Cc: Frank Rowand <frowand.list@gmail.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Rob Herring <robh@kernel.org>
> ---
> Here's a formal patch of what Stan tested. Will send to Linus this week.
>
> Rob
>
> drivers/of/base.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index a055cd1ef96d..17ae594b7014 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;
>
>
Reviewed-by: Frank Rowand <frank.rowand@sony.com>
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