Re: [PATCH] input: twl4030-vibra: Fix ERROR: Bad of_node_put() warning
From: Dr. H. Nikolaus Schaller
Date: Wed Jul 29 2015 - 01:48:05 EST
Hi all,
Am 29.07.2015 um 05:13 schrieb Rob Herring <robherring2@xxxxxxxxx>:
> On Tue, Jul 28, 2015 at 3:23 PM, Belisko Marek <marek.belisko@xxxxxxxxx> wrote:
>> Hi Dmitry,
>>
>> On Thu, Jul 23, 2015 at 10:53 PM, Dmitry Torokhov
>> <dmitry.torokhov@xxxxxxxxx> 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@48070000/twl@48/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.
Fine!
We have a similar error on OMAP5 here:
[ 11.027144] CPU: 1 PID: 6 Comm: kworker/u4:0 Not tainted 4.2.0-rc4-letux+ #1187
[ 11.034790] Hardware name: Generic OMAP5 (Flattened Device Tree)
[ 11.041077] Workqueue: deferwq deferred_probe_work_func
[ 11.046557] [<c0015a00>] (unwind_backtrace) from [<c00124a0>] (show_stack+0x10/0x14)
[ 11.054663] [<c00124a0>] (show_stack) from [<c05cb694>] (dump_stack+0x78/0x94)
[ 11.062224] [<c05cb694>] (dump_stack) from [<c02cfd5c>] (kobject_release+0x68/0x7c)
[ 11.070234] [<c02cfd5c>] (kobject_release) from [<c03291d8>] (omapdss_of_find_source_for_first_ep+0x58/0x74)
[ 11.080510] [<c03291d8>] (omapdss_of_find_source_for_first_ep) from [<bf089290>] (hdmic_probe+0xb4/0x22c [connector_hdmi])
[ 11.092080] [<bf089290>] (hdmic_probe [connector_hdmi]) from [<c0381490>] (platform_drv_probe+0x48/0x90)
[ 11.101997] [<c0381490>] (platform_drv_probe) from [<c037fc98>] (really_probe+0xd4/0x238)
[ 11.110556] [<c037fc98>] (really_probe) from [<c037ff44>] (driver_probe_device+0x30/0x48)
[ 11.119108] [<c037ff44>] (driver_probe_device) from [<c037e7bc>] (bus_for_each_drv+0x4c/0x84)
[ 11.128023] [<c037e7bc>] (bus_for_each_drv) from [<c037fe90>] (__device_attach+0x70/0xd0)
[ 11.136579] [<c037fe90>] (__device_attach) from [<c037f3f8>] (bus_probe_device+0x28/0x84)
[ 11.145135] [<c037f3f8>] (bus_probe_device) from [<c037f808>] (deferred_probe_work_func+0x58/0x88)
[ 11.154518] [<c037f808>] (deferred_probe_work_func) from [<c0054ff0>] (process_one_work+0x294/0x4a0)
[ 11.164083] [<c0054ff0>] (process_one_work) from [<c0055414>] (worker_thread+0x1ec/0x2fc)
[ 11.172641] [<c0055414>] (worker_thread) from [<c005a3b4>] (kthread+0xd4/0xe8)
[ 11.180200] [<c005a3b4>] (kthread) from [<c000edf8>] (ret_from_fork+0x14/0x3c)
So it looks as if there are more get/put mismatches in the drivers which are usually not visible.
>
> 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.
Further analysis turns out that we recently have enabled DRM_TILCDC_SLAVE_COMPAT=y
which we need to make our uImage additionally support the BeagleBone Black with LDC panel
(as mandated by arch/arm/boot/dts/am335x-boneblack.dts using “ti,tilcdc,slave”).
This automatically enables OF_OVERLAY which enables OF_DYNAMIC.
Obviously this now has unexpected side-effects on other systems with universal kernels configured
to support both, beaglebone and non-beaglebone devices.
So what is wrong? The sequence DRM_TILCDC_SLAVE_COMPAT => set OF_OVERLAY => set OF_DYNAMIC?
Or of_node_get/put() bugs in some drivers revealed by running the unit tests?
I have added Tomi to the discussion and we will try to understand/fix omapdss_of_find_source_for_first_ep().
BR,
Nikolaus
>
> Rob
>
>>>
>>> Thanks.
>>>
>>>>
>>>> Signed-off-by: Marek Belisko <marek@xxxxxxxxxxxxx>
>>>> ---
>>>> 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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