[PATCH] of: Fix uninitialized child warning in for_each_child_of_node() if !OF

[PATCH] of: Fix uninitialized child warning in for_each_child_of_node() if !OF

[Geert Uytterhoeven]

If CONFIG_OF=n:

drivers/i2c/i2c-mux.c: In function ‘i2c_add_mux_adapter’:
drivers/i2c/i2c-mux.c:158: warning: ‘child’ is used uninitialized in this function
drivers/leds/leds-lp55xx-common.c: In function ‘lp55xx_of_populate_pdata’:
drivers/leds/leds-lp55xx-common.c:560: warning: ‘child’ is used uninitialized in this function
drivers/leds/leds-pwm.c: In function ‘led_pwm_probe’:
drivers/leds/leds-pwm.c:89: warning: ‘child’ is used uninitialized in this function
drivers/mfd/stmpe.c: In function ‘stmpe_of_probe’:
drivers/mfd/stmpe.c:1112: warning: ‘child’ is used uninitialized in this function
drivers/mfd/tc3589x.c: In function ‘tc3589x_probe’:
drivers/mfd/tc3589x.c:324: warning: ‘child’ is used uninitialized in this function
drivers/power/charger-manager.c: In function ‘of_cm_parse_desc’:
drivers/power/charger-manager.c:1606: warning: ‘child’ is used uninitialized in this function

Introduced by commit 00b2c76a6abbe082bb5afb89ee49ec325e9cd4d2
("include/linux/of.h: make for_each_child_of_node() reference its args when
CONFIG_OF=n").

Instead of dropping the "__of_use_dn(child)" again, explicitly set child
to NULL, to protect against code using child after the loop (child == NULL
is the loop termination condition if CONFIG_OF=y).

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 include/linux/of.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/of.h b/include/linux/of.h
index 70c64ba17fa5..0bf44f2fe092 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -383,7 +383,7 @@ static inline void __of_use_dn(const struct device_node *np)
 }
 
 #define for_each_child_of_node(parent, child) \
-	while (__of_use_dn(parent), __of_use_dn(child), 0)
+	while (__of_use_dn(parent), child = NULL, 0)
 
 #define for_each_available_child_of_node(parent, child) \
 	while (0)
-- 
1.7.9.5

Re: [PATCH] of: Fix uninitialized child warning in for_each_child_of_node() if !OF

[Rob Herring]

On Sun, Jan 26, 2014 at 4:21 AM, Geert Uytterhoeven
<geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org> wrote:
> If CONFIG_OF=n:
>
> drivers/i2c/i2c-mux.c: In function ‘i2c_add_mux_adapter’:
> drivers/i2c/i2c-mux.c:158: warning: ‘child’ is used uninitialized in this function
> drivers/leds/leds-lp55xx-common.c: In function ‘lp55xx_of_populate_pdata’:
> drivers/leds/leds-lp55xx-common.c:560: warning: ‘child’ is used uninitialized in this function
> drivers/leds/leds-pwm.c: In function ‘led_pwm_probe’:
> drivers/leds/leds-pwm.c:89: warning: ‘child’ is used uninitialized in this function
> drivers/mfd/stmpe.c: In function ‘stmpe_of_probe’:
> drivers/mfd/stmpe.c:1112: warning: ‘child’ is used uninitialized in this function
> drivers/mfd/tc3589x.c: In function ‘tc3589x_probe’:
> drivers/mfd/tc3589x.c:324: warning: ‘child’ is used uninitialized in this function
> drivers/power/charger-manager.c: In function ‘of_cm_parse_desc’:
> drivers/power/charger-manager.c:1606: warning: ‘child’ is used uninitialized in this function
>
> Introduced by commit 00b2c76a6abbe082bb5afb89ee49ec325e9cd4d2
> ("include/linux/of.h: make for_each_child_of_node() reference its args when
> CONFIG_OF=n").
>
> Instead of dropping the "__of_use_dn(child)" again, explicitly set child
> to NULL, to protect against code using child after the loop (child == NULL
> is the loop termination condition if CONFIG_OF=y).
>
> Signed-off-by: Geert Uytterhoeven <geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>

Just got fixed in mainline:

commit 00b2c76a6abbe082bb5afb89ee49ec325e9cd4d2
Author: David Howells <dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Date:   Thu Jan 23 15:54:02 2014 -0800

    include/linux/of.h: make for_each_child_of_node() reference its
args when CONFIG_OF=n

    Make for_each_child_of_node() reference its args when CONFIG_OF=n to
    avoid warnings like:

        drivers/leds/leds-pwm.c:88:22: warning: unused variable 'node'
[-Wunused-variable]
          struct device_node *node = pdev->dev.of_node;
                              ^

    Signed-off-by: David Howells <dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
    Cc: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
    Cc: Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
    Signed-off-by: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
    Signed-off-by: Linus Torvalds <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>


> ---
>  include/linux/of.h |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 70c64ba17fa5..0bf44f2fe092 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -383,7 +383,7 @@ static inline void __of_use_dn(const struct device_node *np)
>  }
>
>  #define for_each_child_of_node(parent, child) \
> -       while (__of_use_dn(parent), __of_use_dn(child), 0)
> +       while (__of_use_dn(parent), child = NULL, 0)
>
>  #define for_each_available_child_of_node(parent, child) \
>         while (0)
> --
> 1.7.9.5
>
> --
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Re: [PATCH] of: Fix uninitialized child warning in for_each_child_of_node() if !OF

[Geert Uytterhoeven]

On Mon, Jan 27, 2014 at 3:16 PM, Rob Herring <robherring2@gmail.com> wrote:
> On Sun, Jan 26, 2014 at 4:21 AM, Geert Uytterhoeven
> <geert@linux-m68k.org> wrote:
>> If CONFIG_OF=n:
>>
>> drivers/i2c/i2c-mux.c: In function ‘i2c_add_mux_adapter’:
>> drivers/i2c/i2c-mux.c:158: warning: ‘child’ is used uninitialized in this function
>> drivers/leds/leds-lp55xx-common.c: In function ‘lp55xx_of_populate_pdata’:
>> drivers/leds/leds-lp55xx-common.c:560: warning: ‘child’ is used uninitialized in this function
>> drivers/leds/leds-pwm.c: In function ‘led_pwm_probe’:
>> drivers/leds/leds-pwm.c:89: warning: ‘child’ is used uninitialized in this function
>> drivers/mfd/stmpe.c: In function ‘stmpe_of_probe’:
>> drivers/mfd/stmpe.c:1112: warning: ‘child’ is used uninitialized in this function
>> drivers/mfd/tc3589x.c: In function ‘tc3589x_probe’:
>> drivers/mfd/tc3589x.c:324: warning: ‘child’ is used uninitialized in this function
>> drivers/power/charger-manager.c: In function ‘of_cm_parse_desc’:
>> drivers/power/charger-manager.c:1606: warning: ‘child’ is used uninitialized in this function
>>
>> Introduced by commit 00b2c76a6abbe082bb5afb89ee49ec325e9cd4d2
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> ("include/linux/of.h: make for_each_child_of_node() reference its args when
>> CONFIG_OF=n").
>>
>> Instead of dropping the "__of_use_dn(child)" again, explicitly set child
>> to NULL, to protect against code using child after the loop (child == NULL
>> is the loop termination condition if CONFIG_OF=y).
>>
>> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
>
> Just got fixed in mainline:
>
> commit 00b2c76a6abbe082bb5afb89ee49ec325e9cd4d2

Nope, this is the one that introduced new warnings.

> Author: David Howells <dhowells@redhat.com>
> Date:   Thu Jan 23 15:54:02 2014 -0800
>
>     include/linux/of.h: make for_each_child_of_node() reference its
> args when CONFIG_OF=n
>
>     Make for_each_child_of_node() reference its args when CONFIG_OF=n to
>     avoid warnings like:
>
>         drivers/leds/leds-pwm.c:88:22: warning: unused variable 'node'
> [-Wunused-variable]
>           struct device_node *node = pdev->dev.of_node;
>                               ^
>
>     Signed-off-by: David Howells <dhowells@redhat.com>
>     Cc: Grant Likely <grant.likely@linaro.org>
>     Cc: Rob Herring <robh+dt@kernel.org>
>     Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
>     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>




-- 
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

Re: [PATCH] of: Fix uninitialized child warning in for_each_child_of_node() if !OF

[Rob Herring]

On Mon, Jan 27, 2014 at 8:52 AM, Geert Uytterhoeven
<geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org> wrote:
> On Mon, Jan 27, 2014 at 3:16 PM, Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> On Sun, Jan 26, 2014 at 4:21 AM, Geert Uytterhoeven
>> <geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org> wrote:
>>> If CONFIG_OF=n:
>>>
>>> drivers/i2c/i2c-mux.c: In function ‘i2c_add_mux_adapter’:
>>> drivers/i2c/i2c-mux.c:158: warning: ‘child’ is used uninitialized in this function
>>> drivers/leds/leds-lp55xx-common.c: In function ‘lp55xx_of_populate_pdata’:
>>> drivers/leds/leds-lp55xx-common.c:560: warning: ‘child’ is used uninitialized in this function
>>> drivers/leds/leds-pwm.c: In function ‘led_pwm_probe’:
>>> drivers/leds/leds-pwm.c:89: warning: ‘child’ is used uninitialized in this function
>>> drivers/mfd/stmpe.c: In function ‘stmpe_of_probe’:
>>> drivers/mfd/stmpe.c:1112: warning: ‘child’ is used uninitialized in this function
>>> drivers/mfd/tc3589x.c: In function ‘tc3589x_probe’:
>>> drivers/mfd/tc3589x.c:324: warning: ‘child’ is used uninitialized in this function
>>> drivers/power/charger-manager.c: In function ‘of_cm_parse_desc’:
>>> drivers/power/charger-manager.c:1606: warning: ‘child’ is used uninitialized in this function
>>>
>>> Introduced by commit 00b2c76a6abbe082bb5afb89ee49ec325e9cd4d2
>    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>> ("include/linux/of.h: make for_each_child_of_node() reference its args when
>>> CONFIG_OF=n").
>>>
>>> Instead of dropping the "__of_use_dn(child)" again, explicitly set child
>>> to NULL, to protect against code using child after the loop (child == NULL
>>> is the loop termination condition if CONFIG_OF=y).
>>>
>>> Signed-off-by: Geert Uytterhoeven <geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>
>>
>> Just got fixed in mainline:
>>
>> commit 00b2c76a6abbe082bb5afb89ee49ec325e9cd4d2
>
> Nope, this is the one that introduced new warnings.

Oh right, sorry. Read that too fast.

Won't your change trigger warnings from -Wunused-but-set-variable in
cases where child is not used? That would only be enabled for "W=1"
though.

I think the right fix here is all the for_each_X macros should not be
conditional on CONFIG_OF and we should rely on the functions they call
like of_get_next_child to do the right thing for !OF.

Rob
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Re: [PATCH] of: Fix uninitialized child warning in for_each_child_of_node() if !OF

[Geert Uytterhoeven]

On Mon, Jan 27, 2014 at 5:21 PM, Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> On Mon, Jan 27, 2014 at 8:52 AM, Geert Uytterhoeven
> <geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org> wrote:
>> On Mon, Jan 27, 2014 at 3:16 PM, Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>> On Sun, Jan 26, 2014 at 4:21 AM, Geert Uytterhoeven
>>> <geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org> wrote:
>>>> If CONFIG_OF=n:
>>>>
>>>> drivers/i2c/i2c-mux.c: In function ‘i2c_add_mux_adapter’:
>>>> drivers/i2c/i2c-mux.c:158: warning: ‘child’ is used uninitialized in this function
>>>> drivers/leds/leds-lp55xx-common.c: In function ‘lp55xx_of_populate_pdata’:
>>>> drivers/leds/leds-lp55xx-common.c:560: warning: ‘child’ is used uninitialized in this function
>>>> drivers/leds/leds-pwm.c: In function ‘led_pwm_probe’:
>>>> drivers/leds/leds-pwm.c:89: warning: ‘child’ is used uninitialized in this function
>>>> drivers/mfd/stmpe.c: In function ‘stmpe_of_probe’:
>>>> drivers/mfd/stmpe.c:1112: warning: ‘child’ is used uninitialized in this function
>>>> drivers/mfd/tc3589x.c: In function ‘tc3589x_probe’:
>>>> drivers/mfd/tc3589x.c:324: warning: ‘child’ is used uninitialized in this function
>>>> drivers/power/charger-manager.c: In function ‘of_cm_parse_desc’:
>>>> drivers/power/charger-manager.c:1606: warning: ‘child’ is used uninitialized in this function
>>>>
>>>> Introduced by commit 00b2c76a6abbe082bb5afb89ee49ec325e9cd4d2
>>    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>> ("include/linux/of.h: make for_each_child_of_node() reference its args when
>>>> CONFIG_OF=n").
>>>>
>>>> Instead of dropping the "__of_use_dn(child)" again, explicitly set child
>>>> to NULL, to protect against code using child after the loop (child == NULL
>>>> is the loop termination condition if CONFIG_OF=y).
>>>>
>>>> Signed-off-by: Geert Uytterhoeven <geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>
>>>
>>> Just got fixed in mainline:
>>>
>>> commit 00b2c76a6abbe082bb5afb89ee49ec325e9cd4d2
>>
>> Nope, this is the one that introduced new warnings.
>
> Oh right, sorry. Read that too fast.
>
> Won't your change trigger warnings from -Wunused-but-set-variable in
> cases where child is not used? That would only be enabled for "W=1"
> though.
>
> I think the right fix here is all the for_each_X macros should not be
> conditional on CONFIG_OF and we should rely on the functions they call
> like of_get_next_child to do the right thing for !OF.

That's indeed an alternative fix. As long as of_get_next_child() and
friends return NULL, that'll work fine.

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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