Re: [PATCH] input: twl4030-vibra: Fix ERROR: Bad of_node_put() warning

Hi all,

Am 29.07.2015 um 05:13 schrieb Rob Herring [off-list ref]:

On Tue, Jul 28, 2015 at 3:23 PM, Belisko Marek [off-list ref] wrote:

quoted

Hi Dmitry,

On Thu, Jul 23, 2015 at 10:53 PM, Dmitry Torokhov
[off-list ref] wrote:

quoted

On Thu, Jul 23, 2015 at 10:38:34PM +0200, Marek Belisko wrote:

quoted

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

quoted

quoted

Thanks.

quoted

Signed-off-by: Marek Belisko <redacted>
---
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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