linux-kernel - Re: [PATCH] input: twl4030-vibra: Fix ERROR: Bad of_node

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Date:	Tue, 28 Jul 2015 22:13:54 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Belisko Marek <marek.belisko@...il.com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Dr. H. Nikolaus Schaller" <hns@...delico.com>,
	Rob Herring <robh+dt@...nel.org>,
	Grant Likely <grant.likely@...aro.org>
Subject: Re: [PATCH] input: twl4030-vibra: Fix ERROR: Bad of_node_put() warning

On Tue, Jul 28, 2015 at 3:23 PM, Belisko Marek <marek.belisko@...il.com> wrote:
> Hi Dmitry,
>
> On Thu, Jul 23, 2015 at 10:53 PM, Dmitry Torokhov
> <dmitry.torokhov@...il.com> wrote:
>> On Thu, Jul 23, 2015 at 10:38:34PM +0200, Marek Belisko wrote:
>>> Fix following:
>>> [    8.862274] ERROR: Bad of_node_put() on /ocp/i2c@...70000/twl@...audio
>>> [    8.869293] CPU: 0 PID: 1003 Comm: modprobe Not tainted 4.2.0-rc2-letux+ #1175
>>> [    8.876922] Hardware name: Generic OMAP36xx (Flattened Device Tree)
>>> [    8.883514] [<c00159e0>] (unwind_backtrace) from [<c0012488>] (show_stack+0x10/0x14)
>>> [    8.891693] [<c0012488>] (show_stack) from [<c05cb810>] (dump_stack+0x78/0x94)
>>> [    8.899322] [<c05cb810>] (dump_stack) from [<c02cfd5c>] (kobject_release+0x68/0x7c)
>>> [    8.907409] [<c02cfd5c>] (kobject_release) from [<bf0040c4>] (twl4030_vibra_probe+0x74/0x188 [twl4030_vibra])
>>> [    8.917877] [<bf0040c4>] (twl4030_vibra_probe [twl4030_vibra]) from [<c03816ac>] (platform_drv_probe+0x48/0x90)
>>> [    8.928497] [<c03816ac>] (platform_drv_probe) from [<c037feb4>] (really_probe+0xd4/0x238)
>>> [    8.937103] [<c037feb4>] (really_probe) from [<c0380160>] (driver_probe_device+0x30/0x48)
>>> [    8.945678] [<c0380160>] (driver_probe_device) from [<c03801e0>] (__driver_attach+0x68/0x8c)
>>> [    8.954589] [<c03801e0>] (__driver_attach) from [<c037ea60>] (bus_for_each_dev+0x50/0x84)
>>> [    8.963226] [<c037ea60>] (bus_for_each_dev) from [<c037f828>] (bus_add_driver+0xcc/0x1e4)
>>> [    8.971832] [<c037f828>] (bus_add_driver) from [<c0380b60>] (driver_register+0x9c/0xe0)
>>> [    8.980255] [<c0380b60>] (driver_register) from [<c00097e0>] (do_one_initcall+0x100/0x1b8)
>>> [    8.988983] [<c00097e0>] (do_one_initcall) from [<c00b8008>] (do_init_module+0x58/0x1c0)
>>> [    8.997497] [<c00b8008>] (do_init_module) from [<c00b8cac>] (SyS_init_module+0x54/0x64)
>>> [    9.005950] [<c00b8cac>] (SyS_init_module) from [<c000ed20>] (ret_fast_syscall+0x0/0x54)
>>> [    9.015838] input: twl4030:vibrator as /devices/platform/68000000.ocp/48070000.i2c/i2c-0/0-0048/48070000.i2c:twl@48:audio/input/input2
>>>
>>> node passed to of_find_node_by_name is put inside that function and new node
>>> is returned if found. Free returned node not already freed node.
>>
>> Hmm, if of_find_node_by_name() "puts" passed in node should we not "get"
>> it before calling of_find_node_by_name()? The node pointer in question
>> is simply copied from parent device.
> I'm not sure. what I can say is that I cannot see such error in 4.1
> but only in 4.2-rcx.
> Adding Grant and Rob to CC, maybe they know what should be done and
> why I see such error in 4.2-rcx.

The problem was that node passed into of_find_node_by_name is the the
starting point to search, but you should be doing the put on the
returned node. So the patch below is correct.

As far as why in 4.2, it seems you have OF_DYNAMIC enabled in your
config either because you have DT unit test or overlays enabled.
Overlays are now user enable-able in 4.2.

Rob

>>
>> Thanks.
>>
>>>
>>> Signed-off-by: Marek Belisko <marek@...delico.com>
>>> ---
>>>  drivers/input/misc/twl4030-vibra.c | 3 ++-
>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/input/misc/twl4030-vibra.c b/drivers/input/misc/twl4030-vibra.c
>>> index fc17b95..10c4e3d 100644
>>> --- a/drivers/input/misc/twl4030-vibra.c
>>> +++ b/drivers/input/misc/twl4030-vibra.c
>>> @@ -183,7 +183,8 @@ static bool twl4030_vibra_check_coexist(struct twl4030_vibra_data *pdata,
>>>       if (pdata && pdata->coexist)
>>>               return true;
>>>
>>> -     if (of_find_node_by_name(node, "codec")) {
>>> +     node = of_find_node_by_name(node, "codec");
>>> +     if (node) {
>>>               of_node_put(node);
>>>               return true;
>>>       }
>>> --
>>> 1.9.1
>>>
>>
>> --
>> Dmitry
>
> BR,
>
> marek
>
> --
> as simple and primitive as possible
> -------------------------------------------------
> Marek Belisko - OPEN-NANDRA
> Freelance Developer
>
> Ruska Nova Ves 219 | Presov, 08005 Slovak Republic
> Tel: +421 915 052 184
> skype: marekwhite
> twitter: #opennandra
> web: http://open-nandra.com
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