From: Laurentiu Tudor <[email protected]>
software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
software nodes, thus leading to underflow errors. Balance the refcount by
bumping it in the device_create_managed_software_node() function.
The error [1] was encountered after adding a .shutdown() op to our
fsl-mc-bus driver.
[1]
pc : refcount_warn_saturate+0xf8/0x150
lr : refcount_warn_saturate+0xf8/0x150
sp : ffff80001009b920
x29: ffff80001009b920 x28: ffff1a2420318000 x27: 0000000000000000
x26: ffffccac15e7a038 x25: 0000000000000008 x24: ffffccac168e0030
x23: ffff1a2428a82000 x22: 0000000000080000 x21: ffff1a24287b5000
x20: 0000000000000001 x19: ffff1a24261f4400 x18: ffffffffffffffff
x17: 6f72645f726f7272 x16: 0000000000000000 x15: ffff80009009b607
x14: 0000000000000000 x13: ffffccac16602670 x12: 0000000000000a17
x11: 000000000000035d x10: ffffccac16602670 x9 : ffffccac16602670
x8 : 00000000ffffefff x7 : ffffccac1665a670 x6 : ffffccac1665a670
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 00000000ffffffff
x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff1a2420318000
Call trace:
refcount_warn_saturate+0xf8/0x150
kobject_put+0x10c/0x120
software_node_notify+0xd8/0x140
device_platform_notify+0x4c/0xb4
device_del+0x188/0x424
fsl_mc_device_remove+0x2c/0x4c
rebofind sp.c__fsl_mc_device_remove+0x14/0x2c
device_for_each_child+0x5c/0xac
dprc_remove+0x9c/0xc0
fsl_mc_driver_remove+0x28/0x64
__device_release_driver+0x188/0x22c
device_release_driver+0x30/0x50
bus_remove_device+0x128/0x134
device_del+0x16c/0x424
fsl_mc_bus_remove+0x8c/0x114
fsl_mc_bus_shutdown+0x14/0x20
platform_shutdown+0x28/0x40
device_shutdown+0x15c/0x330
__do_sys_reboot+0x218/0x2a0
__arm64_sys_reboot+0x28/0x34
invoke_syscall+0x48/0x114
el0_svc_common+0x40/0xdc
do_el0_svc+0x2c/0x94
el0_svc+0x2c/0x54
el0t_64_sync_handler+0xa8/0x12c
el0t_64_sync+0x198/0x19c
---[ end trace 32eb1c71c7d86821 ]---
Reported-by: Jon Nettleton <[email protected]>
Suggested-by: Heikki Krogerus <[email protected]>
Signed-off-by: Laurentiu Tudor <[email protected]>
---
Changes since RFC:
- use software_node_notify(KOBJ_ADD) instead of directly bumping
refcount (Heikki)
drivers/base/swnode.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
index d1f1a8240120..bdb50a06c82a 100644
--- a/drivers/base/swnode.c
+++ b/drivers/base/swnode.c
@@ -1113,6 +1113,9 @@ int device_create_managed_software_node(struct device *dev,
to_swnode(fwnode)->managed = true;
set_secondary_fwnode(dev, fwnode);
+ if (device_is_registered(dev))
+ software_node_notify(dev, KOBJ_ADD);
+
return 0;
}
EXPORT_SYMBOL_GPL(device_create_managed_software_node);
--
2.17.1
Didn't notice in the first place, sorry about that. I now get this:
sysfs: cannot create duplicate filename
'/devices/platform/808622B7:00/xhci-hcd.1.auto/software_node'
CPU: 3 PID: 1 Comm: swapper/0 Not tainted
5.13.0-next-20210701-g5859a372a858-dirty #62
Hardware name: NXP NXP LX2160ARDB Platform, BIOS EDK II Apr 16 2021
Call trace:
dump_backtrace+0x0/0x1c0
show_stack+0x18/0x28
dump_stack_lvl+0x68/0x84
dump_stack+0x18/0x34
sysfs_warn_dup+0x60/0x80
sysfs_do_create_link_sd.isra.2+0x104/0x108
sysfs_create_link+0x24/0x48
software_node_notify+0xf0/0x148
device_create_managed_software_node+0x90/0xc8
iort_named_component_init+0x90/0xd0
iort_iommu_configure_id+0x94/0x190
acpi_dma_configure_id+0xc8/0x140
platform_dma_configure+0x94/0xb0
really_probe+0x70/0x2f8
__driver_probe_device+0x7c/0xe8
driver_probe_device+0x8c/0x130
__driver_attach+0x98/0xf8
bus_for_each_dev+0x7c/0xd8
driver_attach+0x24/0x30
bus_add_driver+0x154/0x200
driver_register+0x64/0x120
__platform_driver_register+0x28/0x38
xhci_plat_init+0x30/0x3c
do_one_initcall+0x60/0x1d8
kernel_init_freeable+0x238/0x2ac
kernel_init+0x24/0x128
ret_from_fork+0x10/0x18
---
Best Regards, Laurentiu
On 7/16/2021 1:16 PM, [email protected] wrote:
> From: Laurentiu Tudor <[email protected]>
>
> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
> software nodes, thus leading to underflow errors. Balance the refcount by
> bumping it in the device_create_managed_software_node() function.
>
> The error [1] was encountered after adding a .shutdown() op to our
> fsl-mc-bus driver.
>
> [1]
> pc : refcount_warn_saturate+0xf8/0x150
> lr : refcount_warn_saturate+0xf8/0x150
> sp : ffff80001009b920
> x29: ffff80001009b920 x28: ffff1a2420318000 x27: 0000000000000000
> x26: ffffccac15e7a038 x25: 0000000000000008 x24: ffffccac168e0030
> x23: ffff1a2428a82000 x22: 0000000000080000 x21: ffff1a24287b5000
> x20: 0000000000000001 x19: ffff1a24261f4400 x18: ffffffffffffffff
> x17: 6f72645f726f7272 x16: 0000000000000000 x15: ffff80009009b607
> x14: 0000000000000000 x13: ffffccac16602670 x12: 0000000000000a17
> x11: 000000000000035d x10: ffffccac16602670 x9 : ffffccac16602670
> x8 : 00000000ffffefff x7 : ffffccac1665a670 x6 : ffffccac1665a670
> x5 : 0000000000000000 x4 : 0000000000000000 x3 : 00000000ffffffff
> x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff1a2420318000
> Call trace:
> refcount_warn_saturate+0xf8/0x150
> kobject_put+0x10c/0x120
> software_node_notify+0xd8/0x140
> device_platform_notify+0x4c/0xb4
> device_del+0x188/0x424
> fsl_mc_device_remove+0x2c/0x4c
> rebofind sp.c__fsl_mc_device_remove+0x14/0x2c
> device_for_each_child+0x5c/0xac
> dprc_remove+0x9c/0xc0
> fsl_mc_driver_remove+0x28/0x64
> __device_release_driver+0x188/0x22c
> device_release_driver+0x30/0x50
> bus_remove_device+0x128/0x134
> device_del+0x16c/0x424
> fsl_mc_bus_remove+0x8c/0x114
> fsl_mc_bus_shutdown+0x14/0x20
> platform_shutdown+0x28/0x40
> device_shutdown+0x15c/0x330
> __do_sys_reboot+0x218/0x2a0
> __arm64_sys_reboot+0x28/0x34
> invoke_syscall+0x48/0x114
> el0_svc_common+0x40/0xdc
> do_el0_svc+0x2c/0x94
> el0_svc+0x2c/0x54
> el0t_64_sync_handler+0xa8/0x12c
> el0t_64_sync+0x198/0x19c
> ---[ end trace 32eb1c71c7d86821 ]---
>
> Reported-by: Jon Nettleton <[email protected]>
> Suggested-by: Heikki Krogerus <[email protected]>
> Signed-off-by: Laurentiu Tudor <[email protected]>
> ---
> Changes since RFC:
> - use software_node_notify(KOBJ_ADD) instead of directly bumping
> refcount (Heikki)
>
> drivers/base/swnode.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
> index d1f1a8240120..bdb50a06c82a 100644
> --- a/drivers/base/swnode.c
> +++ b/drivers/base/swnode.c
> @@ -1113,6 +1113,9 @@ int device_create_managed_software_node(struct device *dev,
> to_swnode(fwnode)->managed = true;
> set_secondary_fwnode(dev, fwnode);
>
> + if (device_is_registered(dev))
> + software_node_notify(dev, KOBJ_ADD);
> +
> return 0;
> }
> EXPORT_SYMBOL_GPL(device_create_managed_software_node);
>
On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
> From: Laurentiu Tudor <[email protected]>
>
> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
> software nodes, thus leading to underflow errors. Balance the refcount by
> bumping it in the device_create_managed_software_node() function.
>
> The error [1] was encountered after adding a .shutdown() op to our
> fsl-mc-bus driver.
Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
later on), I can tell that probably something is wrong in the ->shutdown()
method itself.
--
With Best Regards,
Andy Shevchenko
On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
<[email protected]> wrote:
>
> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
> > From: Laurentiu Tudor <[email protected]>
> >
> > software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
> > software nodes, thus leading to underflow errors. Balance the refcount by
> > bumping it in the device_create_managed_software_node() function.
> >
> > The error [1] was encountered after adding a .shutdown() op to our
> > fsl-mc-bus driver.
>
> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
> later on), I can tell that probably something is wrong in the ->shutdown()
> method itself.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
Isn't the other alternative to just remove the second kobject_put from
KOBJ_REMOVE ?
@@ -1149,7 +1147,6 @@ int software_node_notify(struct device *dev,
unsigned long action)
if (swnode->managed) {
set_secondary_fwnode(dev, NULL);
- kobject_put(&swnode->kobj);
}
break;
default:
If we aren't being incremented in device_create_managed_software_node() then
should we be decremented here?
-Jon
On 7/16/2021 8:21 PM, Jon Nettleton wrote:
> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
> <[email protected]> wrote:
>>
>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
>>> From: Laurentiu Tudor <[email protected]>
>>>
>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
>>> software nodes, thus leading to underflow errors. Balance the refcount by
>>> bumping it in the device_create_managed_software_node() function.
>>>
>>> The error [1] was encountered after adding a .shutdown() op to our
>>> fsl-mc-bus driver.
>>
>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
>> later on), I can tell that probably something is wrong in the ->shutdown()
>> method itself.
>>
>> --
>> With Best Regards,
>> Andy Shevchenko
>>
>>
>
> Isn't the other alternative to just remove the second kobject_put from
> KOBJ_REMOVE ?
>
Or maybe on top of Heikki's suggestion, replace the calls to
sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
---
Best Regards, Laurentiu
On Mon, Jul 19, 2021 at 03:00:17PM +0300, Laurentiu Tudor wrote:
> On 7/16/2021 8:21 PM, Jon Nettleton wrote:
> > On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
> > <[email protected]> wrote:
> >>
> >> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
> >>> From: Laurentiu Tudor <[email protected]>
> >>>
> >>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
> >>> software nodes, thus leading to underflow errors. Balance the refcount by
> >>> bumping it in the device_create_managed_software_node() function.
> >>>
> >>> The error [1] was encountered after adding a .shutdown() op to our
> >>> fsl-mc-bus driver.
> >>
> >> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
> >> later on), I can tell that probably something is wrong in the ->shutdown()
> >> method itself.
> >
> > Isn't the other alternative to just remove the second kobject_put from
> > KOBJ_REMOVE ?
> >
>
> Or maybe on top of Heikki's suggestion, replace the calls to
> sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
_noearn will hide the problem. It was there, it was removed from there.
Perhaps we have to understand the root cause better (some specific flow?).
Any insight from you on the flow when the issue appears? I.o.w. what happened
on the big picture that we got into the warning you see?
--
With Best Regards,
Andy Shevchenko
On 7/19/2021 3:22 PM, Andy Shevchenko wrote:
> On Mon, Jul 19, 2021 at 03:00:17PM +0300, Laurentiu Tudor wrote:
>> On 7/16/2021 8:21 PM, Jon Nettleton wrote:
>>> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
>>> <[email protected]> wrote:
>>>>
>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
>>>>> From: Laurentiu Tudor <[email protected]>
>>>>>
>>>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
>>>>> software nodes, thus leading to underflow errors. Balance the refcount by
>>>>> bumping it in the device_create_managed_software_node() function.
>>>>>
>>>>> The error [1] was encountered after adding a .shutdown() op to our
>>>>> fsl-mc-bus driver.
>>>>
>>>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
>>>> later on), I can tell that probably something is wrong in the ->shutdown()
>>>> method itself.
>>>
>>> Isn't the other alternative to just remove the second kobject_put from
>>> KOBJ_REMOVE ?
>>>
>>
>> Or maybe on top of Heikki's suggestion, replace the calls to
>> sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
>
> _noearn will hide the problem. It was there, it was removed from there.
> Perhaps we have to understand the root cause better (some specific flow?).
>
> Any insight from you on the flow when the issue appears? I.o.w. what happened
> on the big picture that we got into the warning you see?
>
I encountered the initial issue when trying to shut down a system booted
with ACPI but only after adding a .shutdown() callback to our bus driver
so that the devices are properly taken down. The problem was that
software_node_notify(), on KOBJ_REMOVE was dropping the reference count
twice leading to an underflow error. My initial proposal was to just
bump the refcount in device_create_managed_software_node(). The device
properties that triggered the problem are created here [1].
Heikko suggested that instead of manually incrementing the refcount to
use software_node_notify(KOBJ_ADD). This triggered the second issue, a
duplicated sysfs entry warning originating in the usb subsystem:
device_create_managed_software_node() ends up being called twice, once
here [2] and secondly, the place I previous mentioned [1].
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/acpi/arm64/iort.c#n952
[2]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/dwc3/host.c#n111
---
Best Regards, Laurentiu
On Tue, Jul 20, 2021 at 12:22 PM Laurentiu Tudor
<[email protected]> wrote:
> On 7/19/2021 3:22 PM, Andy Shevchenko wrote:
> > On Mon, Jul 19, 2021 at 03:00:17PM +0300, Laurentiu Tudor wrote:
> >> On 7/16/2021 8:21 PM, Jon Nettleton wrote:
> >>> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
> >>> <[email protected]> wrote:
> >>>>
> >>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
> >>>>> From: Laurentiu Tudor <[email protected]>
> >>>>>
> >>>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
> >>>>> software nodes, thus leading to underflow errors. Balance the refcount by
> >>>>> bumping it in the device_create_managed_software_node() function.
> >>>>>
> >>>>> The error [1] was encountered after adding a .shutdown() op to our
> >>>>> fsl-mc-bus driver.
> >>>>
> >>>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
> >>>> later on), I can tell that probably something is wrong in the ->shutdown()
> >>>> method itself.
> >>>
> >>> Isn't the other alternative to just remove the second kobject_put from
> >>> KOBJ_REMOVE ?
> >>
> >> Or maybe on top of Heikki's suggestion, replace the calls to
> >> sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
> >
> > _noearn will hide the problem. It was there, it was removed from there.
> > Perhaps we have to understand the root cause better (some specific flow?).
> >
> > Any insight from you on the flow when the issue appears? I.o.w. what happened
> > on the big picture that we got into the warning you see?
>
> I encountered the initial issue when trying to shut down a system booted
> with ACPI but only after adding a .shutdown() callback to our bus driver
> so that the devices are properly taken down. The problem was that
> software_node_notify(), on KOBJ_REMOVE was dropping the reference count
> twice leading to an underflow error. My initial proposal was to just
> bump the refcount in device_create_managed_software_node(). The device
> properties that triggered the problem are created here [1].
>
> Heikko suggested that instead of manually incrementing the refcount to
> use software_node_notify(KOBJ_ADD). This triggered the second issue, a
> duplicated sysfs entry warning originating in the usb subsystem:
> device_create_managed_software_node() ends up being called twice, once
> here [2] and secondly, the place I previous mentioned [1].
This [3] is what I have reported against DWC3 when ->shutdown() has
been added there. And here [4] is another thread about the issue with
that callback. The ->release() callback is called at put_device() [5]
and ->shutdown() is called before that [6]. That said, can you inspect
your ->shutdown() implementation once more time and perhaps see if
there is anything that can be amended?
> [1]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/acpi/arm64/iort.c#n952
> [2]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/dwc3/host.c#n111
[3]: https://lore.kernel.org/linux-usb/CAHp75Vd-5U5zgtDfM5C3Jsx51HVYB+rNcHYC2XP=G7dOd=cdTg@mail.gmail.com/
[4]: https://lore.kernel.org/linux-usb/[email protected]/T/#u
[5]: https://elixir.bootlin.com/linux/latest/source/drivers/base/core.c#L2216
[6]: https://elixir.bootlin.com/linux/latest/source/drivers/base/core.c#L4447
--
With Best Regards,
Andy Shevchenko
On 7/20/2021 1:27 PM, Andy Shevchenko wrote:
> On Tue, Jul 20, 2021 at 12:22 PM Laurentiu Tudor
> <[email protected]> wrote:
>> On 7/19/2021 3:22 PM, Andy Shevchenko wrote:
>>> On Mon, Jul 19, 2021 at 03:00:17PM +0300, Laurentiu Tudor wrote:
>>>> On 7/16/2021 8:21 PM, Jon Nettleton wrote:
>>>>> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
>>>>> <[email protected]> wrote:
>>>>>>
>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
>>>>>>> From: Laurentiu Tudor <[email protected]>
>>>>>>>
>>>>>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
>>>>>>> software nodes, thus leading to underflow errors. Balance the refcount by
>>>>>>> bumping it in the device_create_managed_software_node() function.
>>>>>>>
>>>>>>> The error [1] was encountered after adding a .shutdown() op to our
>>>>>>> fsl-mc-bus driver.
>>>>>>
>>>>>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
>>>>>> later on), I can tell that probably something is wrong in the ->shutdown()
>>>>>> method itself.
>>>>>
>>>>> Isn't the other alternative to just remove the second kobject_put from
>>>>> KOBJ_REMOVE ?
>>>>
>>>> Or maybe on top of Heikki's suggestion, replace the calls to
>>>> sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
>>>
>>> _noearn will hide the problem. It was there, it was removed from there.
>>> Perhaps we have to understand the root cause better (some specific flow?).
>>>
>>> Any insight from you on the flow when the issue appears? I.o.w. what happened
>>> on the big picture that we got into the warning you see?
>>
>> I encountered the initial issue when trying to shut down a system booted
>> with ACPI but only after adding a .shutdown() callback to our bus driver
>> so that the devices are properly taken down. The problem was that
>> software_node_notify(), on KOBJ_REMOVE was dropping the reference count
>> twice leading to an underflow error. My initial proposal was to just
>> bump the refcount in device_create_managed_software_node(). The device
>> properties that triggered the problem are created here [1].
>>
>> Heikko suggested that instead of manually incrementing the refcount to
>> use software_node_notify(KOBJ_ADD). This triggered the second issue, a
>> duplicated sysfs entry warning originating in the usb subsystem:
>> device_create_managed_software_node() ends up being called twice, once
>> here [2] and secondly, the place I previous mentioned [1].
>
> This [3] is what I have reported against DWC3 when ->shutdown() has
> been added there. And here [4] is another thread about the issue with
> that callback. The ->release() callback is called at put_device() [5]
> and ->shutdown() is called before that [6]. That said, can you inspect
> your ->shutdown() implementation once more time and perhaps see if
> there is anything that can be amended?
>
Will do, thanks for the pointers. It could be that we mess something out
in how we use the driver model.
---
Best Regards, Laurentiu
On 7/26/2021 10:59 AM, Laurentiu Tudor wrote:
>
>
> On 7/20/2021 1:27 PM, Andy Shevchenko wrote:
>> On Tue, Jul 20, 2021 at 12:22 PM Laurentiu Tudor
>> <[email protected]> wrote:
>>> On 7/19/2021 3:22 PM, Andy Shevchenko wrote:
>>>> On Mon, Jul 19, 2021 at 03:00:17PM +0300, Laurentiu Tudor wrote:
>>>>> On 7/16/2021 8:21 PM, Jon Nettleton wrote:
>>>>>> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
>>>>>> <[email protected]> wrote:
>>>>>>>
>>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
>>>>>>>> From: Laurentiu Tudor <[email protected]>
>>>>>>>>
>>>>>>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
>>>>>>>> software nodes, thus leading to underflow errors. Balance the refcount by
>>>>>>>> bumping it in the device_create_managed_software_node() function.
>>>>>>>>
>>>>>>>> The error [1] was encountered after adding a .shutdown() op to our
>>>>>>>> fsl-mc-bus driver.
>>>>>>>
>>>>>>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
>>>>>>> later on), I can tell that probably something is wrong in the ->shutdown()
>>>>>>> method itself.
>>>>>>
>>>>>> Isn't the other alternative to just remove the second kobject_put from
>>>>>> KOBJ_REMOVE ?
>>>>>
>>>>> Or maybe on top of Heikki's suggestion, replace the calls to
>>>>> sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
>>>>
>>>> _noearn will hide the problem. It was there, it was removed from there.
>>>> Perhaps we have to understand the root cause better (some specific flow?).
>>>>
>>>> Any insight from you on the flow when the issue appears? I.o.w. what happened
>>>> on the big picture that we got into the warning you see?
>>>
>>> I encountered the initial issue when trying to shut down a system booted
>>> with ACPI but only after adding a .shutdown() callback to our bus driver
>>> so that the devices are properly taken down. The problem was that
>>> software_node_notify(), on KOBJ_REMOVE was dropping the reference count
>>> twice leading to an underflow error. My initial proposal was to just
>>> bump the refcount in device_create_managed_software_node(). The device
>>> properties that triggered the problem are created here [1].
>>>
>>> Heikko suggested that instead of manually incrementing the refcount to
>>> use software_node_notify(KOBJ_ADD). This triggered the second issue, a
>>> duplicated sysfs entry warning originating in the usb subsystem:
>>> device_create_managed_software_node() ends up being called twice, once
>>> here [2] and secondly, the place I previous mentioned [1].
>>
>> This [3] is what I have reported against DWC3 when ->shutdown() has
>> been added there. And here [4] is another thread about the issue with
>> that callback. The ->release() callback is called at put_device() [5]
>> and ->shutdown() is called before that [6]. That said, can you inspect
>> your ->shutdown() implementation once more time and perhaps see if
>> there is anything that can be amended?
>>
>
> Will do, thanks for the pointers. It could be that we mess something out
> in how we use the driver model.
>
Quick (and late, sorry) update from my side. I've spent time on
debugging our bus, did found some issues but, at least for now, none are
related to sw node.
In the mean time, I noticed in the swnode code that
device_add_software_node() calls software_node_notify(KOBJ_ADD) while
device_create_managed_software_node() doesn't. Updating [1] the later
with the call to software_node_notify(KOBJ_ADD) does seem to fix the
issue I'm seeing.
Could this be a problem? Any comments appreciated.
One more thing perhaps worth mentioning is that, at least for now, there
are few uses for this device_create_managed_software_node() api,
mentioning here a couple of them:
- arm64 iort code - this seems to be triggering the issue i'm getting
- dwc3 usb - Andy reported similar issues here, maybe the issue is common?
[1]
@@ -1113,6 +1125,15 @@ int device_create_managed_software_node(struct
device *dev,
to_swnode(fwnode)->managed = true;
set_secondary_fwnode(dev, fwnode);
+ /*
+ * If the device has been fully registered by the time this
function is
+ * called, software_node_notify() must be called separately so
that the
+ * symlinks get created and the reference count of the node is
kept in
+ * balance.
+ */
+ if (device_is_registered(dev))
+ software_node_notify(dev, KOBJ_ADD);
+
return 0;
}
---
Thanks & Best Regards, Laurentiu
On Tue, Sep 07, 2021 at 06:59:18PM +0300, Laurentiu Tudor wrote:
>
>
> On 7/26/2021 10:59 AM, Laurentiu Tudor wrote:
> >
> >
> > On 7/20/2021 1:27 PM, Andy Shevchenko wrote:
> >> On Tue, Jul 20, 2021 at 12:22 PM Laurentiu Tudor
> >> <[email protected]> wrote:
> >>> On 7/19/2021 3:22 PM, Andy Shevchenko wrote:
> >>>> On Mon, Jul 19, 2021 at 03:00:17PM +0300, Laurentiu Tudor wrote:
> >>>>> On 7/16/2021 8:21 PM, Jon Nettleton wrote:
> >>>>>> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
> >>>>>> <[email protected]> wrote:
> >>>>>>>
> >>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
> >>>>>>>> From: Laurentiu Tudor <[email protected]>
> >>>>>>>>
> >>>>>>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
> >>>>>>>> software nodes, thus leading to underflow errors. Balance the refcount by
> >>>>>>>> bumping it in the device_create_managed_software_node() function.
> >>>>>>>>
> >>>>>>>> The error [1] was encountered after adding a .shutdown() op to our
> >>>>>>>> fsl-mc-bus driver.
> >>>>>>>
> >>>>>>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
> >>>>>>> later on), I can tell that probably something is wrong in the ->shutdown()
> >>>>>>> method itself.
> >>>>>>
> >>>>>> Isn't the other alternative to just remove the second kobject_put from
> >>>>>> KOBJ_REMOVE ?
> >>>>>
> >>>>> Or maybe on top of Heikki's suggestion, replace the calls to
> >>>>> sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
> >>>>
> >>>> _noearn will hide the problem. It was there, it was removed from there.
> >>>> Perhaps we have to understand the root cause better (some specific flow?).
> >>>>
> >>>> Any insight from you on the flow when the issue appears? I.o.w. what happened
> >>>> on the big picture that we got into the warning you see?
> >>>
> >>> I encountered the initial issue when trying to shut down a system booted
> >>> with ACPI but only after adding a .shutdown() callback to our bus driver
> >>> so that the devices are properly taken down. The problem was that
> >>> software_node_notify(), on KOBJ_REMOVE was dropping the reference count
> >>> twice leading to an underflow error. My initial proposal was to just
> >>> bump the refcount in device_create_managed_software_node(). The device
> >>> properties that triggered the problem are created here [1].
> >>>
> >>> Heikko suggested that instead of manually incrementing the refcount to
> >>> use software_node_notify(KOBJ_ADD). This triggered the second issue, a
> >>> duplicated sysfs entry warning originating in the usb subsystem:
> >>> device_create_managed_software_node() ends up being called twice, once
> >>> here [2] and secondly, the place I previous mentioned [1].
> >>
> >> This [3] is what I have reported against DWC3 when ->shutdown() has
> >> been added there. And here [4] is another thread about the issue with
> >> that callback. The ->release() callback is called at put_device() [5]
> >> and ->shutdown() is called before that [6]. That said, can you inspect
> >> your ->shutdown() implementation once more time and perhaps see if
> >> there is anything that can be amended?
> >>
> >
> > Will do, thanks for the pointers. It could be that we mess something out
> > in how we use the driver model.
> >
>
> Quick (and late, sorry) update from my side. I've spent time on
> debugging our bus, did found some issues but, at least for now, none are
> related to sw node.
> In the mean time, I noticed in the swnode code that
> device_add_software_node() calls software_node_notify(KOBJ_ADD) while
> device_create_managed_software_node() doesn't. Updating [1] the later
> with the call to software_node_notify(KOBJ_ADD) does seem to fix the
> issue I'm seeing.
>
> Could this be a problem? Any comments appreciated.
>
> One more thing perhaps worth mentioning is that, at least for now, there
> are few uses for this device_create_managed_software_node() api,
> mentioning here a couple of them:
> - arm64 iort code - this seems to be triggering the issue i'm getting
> - dwc3 usb - Andy reported similar issues here, maybe the issue is common?
>
> [1]
> @@ -1113,6 +1125,15 @@ int device_create_managed_software_node(struct
> device *dev,
> to_swnode(fwnode)->managed = true;
> set_secondary_fwnode(dev, fwnode);
>
> + /*
> + * If the device has been fully registered by the time this
> function is
> + * called, software_node_notify() must be called separately so
> that the
> + * symlinks get created and the reference count of the node is
> kept in
> + * balance.
> + */
> + if (device_is_registered(dev))
> + software_node_notify(dev, KOBJ_ADD);
> +
> return 0;
> }
That should be fixed indeed. Please send that after -rc1 is out.
thanks,
--
heikki
On Thu, Sep 09, 2021 at 03:13:47PM +0300, Heikki Krogerus wrote:
> On Tue, Sep 07, 2021 at 06:59:18PM +0300, Laurentiu Tudor wrote:
> >
> >
> > On 7/26/2021 10:59 AM, Laurentiu Tudor wrote:
> > >
> > >
> > > On 7/20/2021 1:27 PM, Andy Shevchenko wrote:
> > >> On Tue, Jul 20, 2021 at 12:22 PM Laurentiu Tudor
> > >> <[email protected]> wrote:
> > >>> On 7/19/2021 3:22 PM, Andy Shevchenko wrote:
> > >>>> On Mon, Jul 19, 2021 at 03:00:17PM +0300, Laurentiu Tudor wrote:
> > >>>>> On 7/16/2021 8:21 PM, Jon Nettleton wrote:
> > >>>>>> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
> > >>>>>> <[email protected]> wrote:
> > >>>>>>>
> > >>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
> > >>>>>>>> From: Laurentiu Tudor <[email protected]>
> > >>>>>>>>
> > >>>>>>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
> > >>>>>>>> software nodes, thus leading to underflow errors. Balance the refcount by
> > >>>>>>>> bumping it in the device_create_managed_software_node() function.
> > >>>>>>>>
> > >>>>>>>> The error [1] was encountered after adding a .shutdown() op to our
> > >>>>>>>> fsl-mc-bus driver.
> > >>>>>>>
> > >>>>>>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
> > >>>>>>> later on), I can tell that probably something is wrong in the ->shutdown()
> > >>>>>>> method itself.
> > >>>>>>
> > >>>>>> Isn't the other alternative to just remove the second kobject_put from
> > >>>>>> KOBJ_REMOVE ?
> > >>>>>
> > >>>>> Or maybe on top of Heikki's suggestion, replace the calls to
> > >>>>> sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
> > >>>>
> > >>>> _noearn will hide the problem. It was there, it was removed from there.
> > >>>> Perhaps we have to understand the root cause better (some specific flow?).
> > >>>>
> > >>>> Any insight from you on the flow when the issue appears? I.o.w. what happened
> > >>>> on the big picture that we got into the warning you see?
> > >>>
> > >>> I encountered the initial issue when trying to shut down a system booted
> > >>> with ACPI but only after adding a .shutdown() callback to our bus driver
> > >>> so that the devices are properly taken down. The problem was that
> > >>> software_node_notify(), on KOBJ_REMOVE was dropping the reference count
> > >>> twice leading to an underflow error. My initial proposal was to just
> > >>> bump the refcount in device_create_managed_software_node(). The device
> > >>> properties that triggered the problem are created here [1].
> > >>>
> > >>> Heikko suggested that instead of manually incrementing the refcount to
> > >>> use software_node_notify(KOBJ_ADD). This triggered the second issue, a
> > >>> duplicated sysfs entry warning originating in the usb subsystem:
> > >>> device_create_managed_software_node() ends up being called twice, once
> > >>> here [2] and secondly, the place I previous mentioned [1].
> > >>
> > >> This [3] is what I have reported against DWC3 when ->shutdown() has
> > >> been added there. And here [4] is another thread about the issue with
> > >> that callback. The ->release() callback is called at put_device() [5]
> > >> and ->shutdown() is called before that [6]. That said, can you inspect
> > >> your ->shutdown() implementation once more time and perhaps see if
> > >> there is anything that can be amended?
> > >>
> > >
> > > Will do, thanks for the pointers. It could be that we mess something out
> > > in how we use the driver model.
> > >
> >
> > Quick (and late, sorry) update from my side. I've spent time on
> > debugging our bus, did found some issues but, at least for now, none are
> > related to sw node.
> > In the mean time, I noticed in the swnode code that
> > device_add_software_node() calls software_node_notify(KOBJ_ADD) while
> > device_create_managed_software_node() doesn't. Updating [1] the later
> > with the call to software_node_notify(KOBJ_ADD) does seem to fix the
> > issue I'm seeing.
> >
> > Could this be a problem? Any comments appreciated.
> >
> > One more thing perhaps worth mentioning is that, at least for now, there
> > are few uses for this device_create_managed_software_node() api,
> > mentioning here a couple of them:
> > - arm64 iort code - this seems to be triggering the issue i'm getting
> > - dwc3 usb - Andy reported similar issues here, maybe the issue is common?
> >
> > [1]
> > @@ -1113,6 +1125,15 @@ int device_create_managed_software_node(struct
> > device *dev,
> > to_swnode(fwnode)->managed = true;
> > set_secondary_fwnode(dev, fwnode);
> >
> > + /*
> > + * If the device has been fully registered by the time this
> > function is
> > + * called, software_node_notify() must be called separately so
> > that the
> > + * symlinks get created and the reference count of the node is
> > kept in
> > + * balance.
> > + */
> > + if (device_is_registered(dev))
> > + software_node_notify(dev, KOBJ_ADD);
> > +
> > return 0;
> > }
>
> That should be fixed indeed. Please send that after -rc1 is out.
I mean, resend :-)
--
heikki
On 9/9/2021 3:16 PM, Heikki Krogerus wrote:
> On Thu, Sep 09, 2021 at 03:13:47PM +0300, Heikki Krogerus wrote:
>> On Tue, Sep 07, 2021 at 06:59:18PM +0300, Laurentiu Tudor wrote:
>>>
>>>
>>> On 7/26/2021 10:59 AM, Laurentiu Tudor wrote:
>>>>
>>>>
>>>> On 7/20/2021 1:27 PM, Andy Shevchenko wrote:
>>>>> On Tue, Jul 20, 2021 at 12:22 PM Laurentiu Tudor
>>>>> <[email protected]> wrote:
>>>>>> On 7/19/2021 3:22 PM, Andy Shevchenko wrote:
>>>>>>> On Mon, Jul 19, 2021 at 03:00:17PM +0300, Laurentiu Tudor wrote:
>>>>>>>> On 7/16/2021 8:21 PM, Jon Nettleton wrote:
>>>>>>>>> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
>>>>>>>>> <[email protected]> wrote:
>>>>>>>>>>
>>>>>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
>>>>>>>>>>> From: Laurentiu Tudor <[email protected]>
>>>>>>>>>>>
>>>>>>>>>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
>>>>>>>>>>> software nodes, thus leading to underflow errors. Balance the refcount by
>>>>>>>>>>> bumping it in the device_create_managed_software_node() function.
>>>>>>>>>>>
>>>>>>>>>>> The error [1] was encountered after adding a .shutdown() op to our
>>>>>>>>>>> fsl-mc-bus driver.
>>>>>>>>>>
>>>>>>>>>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
>>>>>>>>>> later on), I can tell that probably something is wrong in the ->shutdown()
>>>>>>>>>> method itself.
>>>>>>>>>
>>>>>>>>> Isn't the other alternative to just remove the second kobject_put from
>>>>>>>>> KOBJ_REMOVE ?
>>>>>>>>
>>>>>>>> Or maybe on top of Heikki's suggestion, replace the calls to
>>>>>>>> sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
>>>>>>>
>>>>>>> _noearn will hide the problem. It was there, it was removed from there.
>>>>>>> Perhaps we have to understand the root cause better (some specific flow?).
>>>>>>>
>>>>>>> Any insight from you on the flow when the issue appears? I.o.w. what happened
>>>>>>> on the big picture that we got into the warning you see?
>>>>>>
>>>>>> I encountered the initial issue when trying to shut down a system booted
>>>>>> with ACPI but only after adding a .shutdown() callback to our bus driver
>>>>>> so that the devices are properly taken down. The problem was that
>>>>>> software_node_notify(), on KOBJ_REMOVE was dropping the reference count
>>>>>> twice leading to an underflow error. My initial proposal was to just
>>>>>> bump the refcount in device_create_managed_software_node(). The device
>>>>>> properties that triggered the problem are created here [1].
>>>>>>
>>>>>> Heikko suggested that instead of manually incrementing the refcount to
>>>>>> use software_node_notify(KOBJ_ADD). This triggered the second issue, a
>>>>>> duplicated sysfs entry warning originating in the usb subsystem:
>>>>>> device_create_managed_software_node() ends up being called twice, once
>>>>>> here [2] and secondly, the place I previous mentioned [1].
>>>>>
>>>>> This [3] is what I have reported against DWC3 when ->shutdown() has
>>>>> been added there. And here [4] is another thread about the issue with
>>>>> that callback. The ->release() callback is called at put_device() [5]
>>>>> and ->shutdown() is called before that [6]. That said, can you inspect
>>>>> your ->shutdown() implementation once more time and perhaps see if
>>>>> there is anything that can be amended?
>>>>>
>>>>
>>>> Will do, thanks for the pointers. It could be that we mess something out
>>>> in how we use the driver model.
>>>>
>>>
>>> Quick (and late, sorry) update from my side. I've spent time on
>>> debugging our bus, did found some issues but, at least for now, none are
>>> related to sw node.
>>> In the mean time, I noticed in the swnode code that
>>> device_add_software_node() calls software_node_notify(KOBJ_ADD) while
>>> device_create_managed_software_node() doesn't. Updating [1] the later
>>> with the call to software_node_notify(KOBJ_ADD) does seem to fix the
>>> issue I'm seeing.
>>>
>>> Could this be a problem? Any comments appreciated.
>>>
>>> One more thing perhaps worth mentioning is that, at least for now, there
>>> are few uses for this device_create_managed_software_node() api,
>>> mentioning here a couple of them:
>>> - arm64 iort code - this seems to be triggering the issue i'm getting
>>> - dwc3 usb - Andy reported similar issues here, maybe the issue is common?
>>>
>>> [1]
>>> @@ -1113,6 +1125,15 @@ int device_create_managed_software_node(struct
>>> device *dev,
>>> to_swnode(fwnode)->managed = true;
>>> set_secondary_fwnode(dev, fwnode);
>>>
>>> + /*
>>> + * If the device has been fully registered by the time this
>>> function is
>>> + * called, software_node_notify() must be called separately so
>>> that the
>>> + * symlinks get created and the reference count of the node is
>>> kept in
>>> + * balance.
>>> + */
>>> + if (device_is_registered(dev))
>>> + software_node_notify(dev, KOBJ_ADD);
>>> +
>>> return 0;
>>> }
>>
>> That should be fixed indeed. Please send that after -rc1 is out.
>
> I mean, resend :-)
>
Right, actually I just noticed that this is the fix you suggested last
time we discussed. :-) I forgot about it, sorry.
There's still the WARN_ON() [1] triggered by the usb subsys, apparently
happening only (!) in ACPI boot scenario, so +Lorenzo.
I'll delay the sending a bit to try to understand what's going on.
[1]
[ 11.760346] sysfs: cannot create duplicate filename
'/devices/platform/808622B7:01/xhci-hcd.2.auto/software_node'
[ 11.770612] CPU: 9 PID: 1 Comm: swapper/0 Tainted: G W
5.14.0-rc1-00214-gbf7f1083ebd3-dirty #62
[ 11.780611] Hardware name: NXP NXP LX2160ARDB Platform, BIOS EDK II
Apr 16 2021
[ 11.787913] Call trace:
[ 11.790351] dump_backtrace+0x0/0x2a4
[ 11.794017] show_stack+0x1c/0x30
[ 11.797331] dump_stack_lvl+0x68/0x84
[ 11.800991] dump_stack+0x20/0x3c
[ 11.804302] sysfs_warn_dup+0x88/0xac
[ 11.807965] sysfs_do_create_link_sd+0xf8/0x100
[ 11.812492] sysfs_create_link+0x48/0x80
[ 11.816411] software_node_notify+0x1a8/0x35c
[ 11.820769] device_create_managed_software_node+0x158/0x1b0
[ 11.826428] iort_named_component_init+0xe0/0x140
[ 11.831131] iort_iommu_configure_id+0xf4/0x270
[ 11.835660] acpi_dma_configure_id+0x160/0x200
[ 11.840101] platform_dma_configure+0xa0/0xa4
[ 11.844457] really_probe.part.0+0x84/0x480
[ 11.848639] __driver_probe_device+0xd4/0x180
[ 11.852994] driver_probe_device+0xf8/0x1e0
[ 11.857174] __driver_attach+0x108/0x220
[ 11.861095] bus_for_each_dev+0xe4/0x154
[ 11.865014] driver_attach+0x38/0x50
[ 11.868587] bus_add_driver+0x1bc/0x2c4
[ 11.872419] driver_register+0xf0/0x210
[ 11.876253] __platform_driver_register+0x48/0x60
[ 11.880956] xhci_plat_init+0x34/0x40
[ 11.884616] do_one_initcall+0xa8/0x270
[ 11.888449] kernel_init_freeable+0x2c0/0x348
[ 11.892806] kernel_init+0x28/0x140
[ 11.896295] ret_from_fork+0x10/0x18
[ 11.900062] xhci-hcd xhci-hcd.2.auto: Adding to iommu group 6
[ 11.906044] xhci-hcd xhci-hcd.2.auto: xHCI Host Controller
[ 11.911566] xhci-hcd xhci-hcd.2.auto: new USB bus registered,
assigned bus number 3
[ 11.919702] xhci-hcd xhci-hcd.2.auto: hcc params 0x0220f66d hci
version 0x100 quirks 0x0000000000010010
[ 11.929187] xhci-hcd xhci-hcd.2.auto: irq 106, io mem 0x03110000
---
Best Regards, Laurentiu
On 9/9/2021 5:01 PM, Laurentiu Tudor wrote:
>
>
> On 9/9/2021 3:16 PM, Heikki Krogerus wrote:
>> On Thu, Sep 09, 2021 at 03:13:47PM +0300, Heikki Krogerus wrote:
>>> On Tue, Sep 07, 2021 at 06:59:18PM +0300, Laurentiu Tudor wrote:
>>>>
>>>>
>>>> On 7/26/2021 10:59 AM, Laurentiu Tudor wrote:
>>>>>
>>>>>
>>>>> On 7/20/2021 1:27 PM, Andy Shevchenko wrote:
>>>>>> On Tue, Jul 20, 2021 at 12:22 PM Laurentiu Tudor
>>>>>> <[email protected]> wrote:
>>>>>>> On 7/19/2021 3:22 PM, Andy Shevchenko wrote:
>>>>>>>> On Mon, Jul 19, 2021 at 03:00:17PM +0300, Laurentiu Tudor wrote:
>>>>>>>>> On 7/16/2021 8:21 PM, Jon Nettleton wrote:
>>>>>>>>>> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
>>>>>>>>>> <[email protected]> wrote:
>>>>>>>>>>>
>>>>>>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
>>>>>>>>>>>> From: Laurentiu Tudor <[email protected]>
>>>>>>>>>>>>
>>>>>>>>>>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
>>>>>>>>>>>> software nodes, thus leading to underflow errors. Balance the refcount by
>>>>>>>>>>>> bumping it in the device_create_managed_software_node() function.
>>>>>>>>>>>>
>>>>>>>>>>>> The error [1] was encountered after adding a .shutdown() op to our
>>>>>>>>>>>> fsl-mc-bus driver.
>>>>>>>>>>>
>>>>>>>>>>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
>>>>>>>>>>> later on), I can tell that probably something is wrong in the ->shutdown()
>>>>>>>>>>> method itself.
>>>>>>>>>>
>>>>>>>>>> Isn't the other alternative to just remove the second kobject_put from
>>>>>>>>>> KOBJ_REMOVE ?
>>>>>>>>>
>>>>>>>>> Or maybe on top of Heikki's suggestion, replace the calls to
>>>>>>>>> sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
>>>>>>>>
>>>>>>>> _noearn will hide the problem. It was there, it was removed from there.
>>>>>>>> Perhaps we have to understand the root cause better (some specific flow?).
>>>>>>>>
>>>>>>>> Any insight from you on the flow when the issue appears? I.o.w. what happened
>>>>>>>> on the big picture that we got into the warning you see?
>>>>>>>
>>>>>>> I encountered the initial issue when trying to shut down a system booted
>>>>>>> with ACPI but only after adding a .shutdown() callback to our bus driver
>>>>>>> so that the devices are properly taken down. The problem was that
>>>>>>> software_node_notify(), on KOBJ_REMOVE was dropping the reference count
>>>>>>> twice leading to an underflow error. My initial proposal was to just
>>>>>>> bump the refcount in device_create_managed_software_node(). The device
>>>>>>> properties that triggered the problem are created here [1].
>>>>>>>
>>>>>>> Heikko suggested that instead of manually incrementing the refcount to
>>>>>>> use software_node_notify(KOBJ_ADD). This triggered the second issue, a
>>>>>>> duplicated sysfs entry warning originating in the usb subsystem:
>>>>>>> device_create_managed_software_node() ends up being called twice, once
>>>>>>> here [2] and secondly, the place I previous mentioned [1].
>>>>>>
>>>>>> This [3] is what I have reported against DWC3 when ->shutdown() has
>>>>>> been added there. And here [4] is another thread about the issue with
>>>>>> that callback. The ->release() callback is called at put_device() [5]
>>>>>> and ->shutdown() is called before that [6]. That said, can you inspect
>>>>>> your ->shutdown() implementation once more time and perhaps see if
>>>>>> there is anything that can be amended?
>>>>>>
>>>>>
>>>>> Will do, thanks for the pointers. It could be that we mess something out
>>>>> in how we use the driver model.
>>>>>
>>>>
>>>> Quick (and late, sorry) update from my side. I've spent time on
>>>> debugging our bus, did found some issues but, at least for now, none are
>>>> related to sw node.
>>>> In the mean time, I noticed in the swnode code that
>>>> device_add_software_node() calls software_node_notify(KOBJ_ADD) while
>>>> device_create_managed_software_node() doesn't. Updating [1] the later
>>>> with the call to software_node_notify(KOBJ_ADD) does seem to fix the
>>>> issue I'm seeing.
>>>>
>>>> Could this be a problem? Any comments appreciated.
>>>>
>>>> One more thing perhaps worth mentioning is that, at least for now, there
>>>> are few uses for this device_create_managed_software_node() api,
>>>> mentioning here a couple of them:
>>>> - arm64 iort code - this seems to be triggering the issue i'm getting
>>>> - dwc3 usb - Andy reported similar issues here, maybe the issue is common?
>>>>
>>>> [1]
>>>> @@ -1113,6 +1125,15 @@ int device_create_managed_software_node(struct
>>>> device *dev,
>>>> to_swnode(fwnode)->managed = true;
>>>> set_secondary_fwnode(dev, fwnode);
>>>>
>>>> + /*
>>>> + * If the device has been fully registered by the time this
>>>> function is
>>>> + * called, software_node_notify() must be called separately so
>>>> that the
>>>> + * symlinks get created and the reference count of the node is
>>>> kept in
>>>> + * balance.
>>>> + */
>>>> + if (device_is_registered(dev))
>>>> + software_node_notify(dev, KOBJ_ADD);
>>>> +
>>>> return 0;
>>>> }
>>>
>>> That should be fixed indeed. Please send that after -rc1 is out.
>>
>> I mean, resend :-)
>>
>
> Right, actually I just noticed that this is the fix you suggested last
> time we discussed. :-) I forgot about it, sorry.
> There's still the WARN_ON() [1] triggered by the usb subsys, apparently
> happening only (!) in ACPI boot scenario, so +Lorenzo.
> I'll delay the sending a bit to try to understand what's going on.
I've spent some time looking into this and it turns out that in the
ACPI case, device_create_managed_software_node() ends up being called
twice, first here [1] and after that, in the IORT code here [2]. With
the proposed patch this causes software_node_notify(KOBJ_ADD) being
called twice thus triggering the dup sysfs entry warning.
Any comments / ideas welcomed.
[1]
https://elixir.bootlin.com/linux/latest/source/drivers/usb/dwc3/host.c#L111
[2]
https://elixir.bootlin.com/linux/latest/source/drivers/acpi/arm64/iort.c#L952
---
Best Regards, Laurentiu
On Fri, Sep 10, 2021 at 03:05:16PM +0300, Laurentiu Tudor wrote:
>
>
> On 9/9/2021 5:01 PM, Laurentiu Tudor wrote:
> >
> >
> > On 9/9/2021 3:16 PM, Heikki Krogerus wrote:
> >> On Thu, Sep 09, 2021 at 03:13:47PM +0300, Heikki Krogerus wrote:
> >>> On Tue, Sep 07, 2021 at 06:59:18PM +0300, Laurentiu Tudor wrote:
> >>>>
> >>>>
> >>>> On 7/26/2021 10:59 AM, Laurentiu Tudor wrote:
> >>>>>
> >>>>>
> >>>>> On 7/20/2021 1:27 PM, Andy Shevchenko wrote:
> >>>>>> On Tue, Jul 20, 2021 at 12:22 PM Laurentiu Tudor
> >>>>>> <[email protected]> wrote:
> >>>>>>> On 7/19/2021 3:22 PM, Andy Shevchenko wrote:
> >>>>>>>> On Mon, Jul 19, 2021 at 03:00:17PM +0300, Laurentiu Tudor wrote:
> >>>>>>>>> On 7/16/2021 8:21 PM, Jon Nettleton wrote:
> >>>>>>>>>> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
> >>>>>>>>>> <[email protected]> wrote:
> >>>>>>>>>>>
> >>>>>>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
> >>>>>>>>>>>> From: Laurentiu Tudor <[email protected]>
> >>>>>>>>>>>>
> >>>>>>>>>>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
> >>>>>>>>>>>> software nodes, thus leading to underflow errors. Balance the refcount by
> >>>>>>>>>>>> bumping it in the device_create_managed_software_node() function.
> >>>>>>>>>>>>
> >>>>>>>>>>>> The error [1] was encountered after adding a .shutdown() op to our
> >>>>>>>>>>>> fsl-mc-bus driver.
> >>>>>>>>>>>
> >>>>>>>>>>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
> >>>>>>>>>>> later on), I can tell that probably something is wrong in the ->shutdown()
> >>>>>>>>>>> method itself.
> >>>>>>>>>>
> >>>>>>>>>> Isn't the other alternative to just remove the second kobject_put from
> >>>>>>>>>> KOBJ_REMOVE ?
> >>>>>>>>>
> >>>>>>>>> Or maybe on top of Heikki's suggestion, replace the calls to
> >>>>>>>>> sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
> >>>>>>>>
> >>>>>>>> _noearn will hide the problem. It was there, it was removed from there.
> >>>>>>>> Perhaps we have to understand the root cause better (some specific flow?).
> >>>>>>>>
> >>>>>>>> Any insight from you on the flow when the issue appears? I.o.w. what happened
> >>>>>>>> on the big picture that we got into the warning you see?
> >>>>>>>
> >>>>>>> I encountered the initial issue when trying to shut down a system booted
> >>>>>>> with ACPI but only after adding a .shutdown() callback to our bus driver
> >>>>>>> so that the devices are properly taken down. The problem was that
> >>>>>>> software_node_notify(), on KOBJ_REMOVE was dropping the reference count
> >>>>>>> twice leading to an underflow error. My initial proposal was to just
> >>>>>>> bump the refcount in device_create_managed_software_node(). The device
> >>>>>>> properties that triggered the problem are created here [1].
> >>>>>>>
> >>>>>>> Heikko suggested that instead of manually incrementing the refcount to
> >>>>>>> use software_node_notify(KOBJ_ADD). This triggered the second issue, a
> >>>>>>> duplicated sysfs entry warning originating in the usb subsystem:
> >>>>>>> device_create_managed_software_node() ends up being called twice, once
> >>>>>>> here [2] and secondly, the place I previous mentioned [1].
> >>>>>>
> >>>>>> This [3] is what I have reported against DWC3 when ->shutdown() has
> >>>>>> been added there. And here [4] is another thread about the issue with
> >>>>>> that callback. The ->release() callback is called at put_device() [5]
> >>>>>> and ->shutdown() is called before that [6]. That said, can you inspect
> >>>>>> your ->shutdown() implementation once more time and perhaps see if
> >>>>>> there is anything that can be amended?
> >>>>>>
> >>>>>
> >>>>> Will do, thanks for the pointers. It could be that we mess something out
> >>>>> in how we use the driver model.
> >>>>>
> >>>>
> >>>> Quick (and late, sorry) update from my side. I've spent time on
> >>>> debugging our bus, did found some issues but, at least for now, none are
> >>>> related to sw node.
> >>>> In the mean time, I noticed in the swnode code that
> >>>> device_add_software_node() calls software_node_notify(KOBJ_ADD) while
> >>>> device_create_managed_software_node() doesn't. Updating [1] the later
> >>>> with the call to software_node_notify(KOBJ_ADD) does seem to fix the
> >>>> issue I'm seeing.
> >>>>
> >>>> Could this be a problem? Any comments appreciated.
> >>>>
> >>>> One more thing perhaps worth mentioning is that, at least for now, there
> >>>> are few uses for this device_create_managed_software_node() api,
> >>>> mentioning here a couple of them:
> >>>> - arm64 iort code - this seems to be triggering the issue i'm getting
> >>>> - dwc3 usb - Andy reported similar issues here, maybe the issue is common?
> >>>>
> >>>> [1]
> >>>> @@ -1113,6 +1125,15 @@ int device_create_managed_software_node(struct
> >>>> device *dev,
> >>>> to_swnode(fwnode)->managed = true;
> >>>> set_secondary_fwnode(dev, fwnode);
> >>>>
> >>>> + /*
> >>>> + * If the device has been fully registered by the time this
> >>>> function is
> >>>> + * called, software_node_notify() must be called separately so
> >>>> that the
> >>>> + * symlinks get created and the reference count of the node is
> >>>> kept in
> >>>> + * balance.
> >>>> + */
> >>>> + if (device_is_registered(dev))
> >>>> + software_node_notify(dev, KOBJ_ADD);
> >>>> +
> >>>> return 0;
> >>>> }
> >>>
> >>> That should be fixed indeed. Please send that after -rc1 is out.
> >>
> >> I mean, resend :-)
> >>
> >
> > Right, actually I just noticed that this is the fix you suggested last
> > time we discussed. :-) I forgot about it, sorry.
> > There's still the WARN_ON() [1] triggered by the usb subsys, apparently
> > happening only (!) in ACPI boot scenario, so +Lorenzo.
> > I'll delay the sending a bit to try to understand what's going on.
>
> I've spent some time looking into this and it turns out that in the
> ACPI case, device_create_managed_software_node() ends up being called
> twice, first here [1] and after that, in the IORT code here [2]. With
> the proposed patch this causes software_node_notify(KOBJ_ADD) being
> called twice thus triggering the dup sysfs entry warning.
> Any comments / ideas welcomed.
>
> [1] https://elixir.bootlin.com/linux/latest/source/drivers/usb/dwc3/host.c#L111
I think the problem here is that the secondary fwnode get's replaced
because the primary fwnode is shared. Can you test it with this, just
to see if the problem goes away:
diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
index f29a264635aa1..e4b40f8b8f242 100644
--- a/drivers/usb/dwc3/host.c
+++ b/drivers/usb/dwc3/host.c
@@ -76,7 +76,6 @@ int dwc3_host_init(struct dwc3 *dwc)
}
xhci->dev.parent = dwc->dev;
- ACPI_COMPANION_SET(&xhci->dev, ACPI_COMPANION(dwc->dev));
dwc->xhci = xhci;
> [2] https://elixir.bootlin.com/linux/latest/source/drivers/acpi/arm64/iort.c#L952
I didn't yet look at that one.
thanks,
--
heikki
Hi Heikki,
On 9/10/2021 3:38 PM, Heikki Krogerus wrote:
> On Fri, Sep 10, 2021 at 03:05:16PM +0300, Laurentiu Tudor wrote:
>>
>>
>> On 9/9/2021 5:01 PM, Laurentiu Tudor wrote:
>>>
>>>
>>> On 9/9/2021 3:16 PM, Heikki Krogerus wrote:
>>>> On Thu, Sep 09, 2021 at 03:13:47PM +0300, Heikki Krogerus wrote:
>>>>> On Tue, Sep 07, 2021 at 06:59:18PM +0300, Laurentiu Tudor wrote:
>>>>>>
>>>>>>
>>>>>> On 7/26/2021 10:59 AM, Laurentiu Tudor wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 7/20/2021 1:27 PM, Andy Shevchenko wrote:
>>>>>>>> On Tue, Jul 20, 2021 at 12:22 PM Laurentiu Tudor
>>>>>>>> <[email protected]> wrote:
>>>>>>>>> On 7/19/2021 3:22 PM, Andy Shevchenko wrote:
>>>>>>>>>> On Mon, Jul 19, 2021 at 03:00:17PM +0300, Laurentiu Tudor wrote:
>>>>>>>>>>> On 7/16/2021 8:21 PM, Jon Nettleton wrote:
>>>>>>>>>>>> On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko
>>>>>>>>>>>> <[email protected]> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
>>>>>>>>>>>>>> From: Laurentiu Tudor <[email protected]>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
>>>>>>>>>>>>>> software nodes, thus leading to underflow errors. Balance the refcount by
>>>>>>>>>>>>>> bumping it in the device_create_managed_software_node() function.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> The error [1] was encountered after adding a .shutdown() op to our
>>>>>>>>>>>>>> fsl-mc-bus driver.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Looking into the history of adding ->shutdown() to dwc3 driver (it got reverted
>>>>>>>>>>>>> later on), I can tell that probably something is wrong in the ->shutdown()
>>>>>>>>>>>>> method itself.
>>>>>>>>>>>>
>>>>>>>>>>>> Isn't the other alternative to just remove the second kobject_put from
>>>>>>>>>>>> KOBJ_REMOVE ?
>>>>>>>>>>>
>>>>>>>>>>> Or maybe on top of Heikki's suggestion, replace the calls to
>>>>>>>>>>> sysfs_create_link() from KOBJ_ADD with sysfs_create_link_nowarn()?
>>>>>>>>>>
>>>>>>>>>> _noearn will hide the problem. It was there, it was removed from there.
>>>>>>>>>> Perhaps we have to understand the root cause better (some specific flow?).
>>>>>>>>>>
>>>>>>>>>> Any insight from you on the flow when the issue appears? I.o.w. what happened
>>>>>>>>>> on the big picture that we got into the warning you see?
>>>>>>>>>
>>>>>>>>> I encountered the initial issue when trying to shut down a system booted
>>>>>>>>> with ACPI but only after adding a .shutdown() callback to our bus driver
>>>>>>>>> so that the devices are properly taken down. The problem was that
>>>>>>>>> software_node_notify(), on KOBJ_REMOVE was dropping the reference count
>>>>>>>>> twice leading to an underflow error. My initial proposal was to just
>>>>>>>>> bump the refcount in device_create_managed_software_node(). The device
>>>>>>>>> properties that triggered the problem are created here [1].
>>>>>>>>>
>>>>>>>>> Heikko suggested that instead of manually incrementing the refcount to
>>>>>>>>> use software_node_notify(KOBJ_ADD). This triggered the second issue, a
>>>>>>>>> duplicated sysfs entry warning originating in the usb subsystem:
>>>>>>>>> device_create_managed_software_node() ends up being called twice, once
>>>>>>>>> here [2] and secondly, the place I previous mentioned [1].
>>>>>>>>
>>>>>>>> This [3] is what I have reported against DWC3 when ->shutdown() has
>>>>>>>> been added there. And here [4] is another thread about the issue with
>>>>>>>> that callback. The ->release() callback is called at put_device() [5]
>>>>>>>> and ->shutdown() is called before that [6]. That said, can you inspect
>>>>>>>> your ->shutdown() implementation once more time and perhaps see if
>>>>>>>> there is anything that can be amended?
>>>>>>>>
>>>>>>>
>>>>>>> Will do, thanks for the pointers. It could be that we mess something out
>>>>>>> in how we use the driver model.
>>>>>>>
>>>>>>
>>>>>> Quick (and late, sorry) update from my side. I've spent time on
>>>>>> debugging our bus, did found some issues but, at least for now, none are
>>>>>> related to sw node.
>>>>>> In the mean time, I noticed in the swnode code that
>>>>>> device_add_software_node() calls software_node_notify(KOBJ_ADD) while
>>>>>> device_create_managed_software_node() doesn't. Updating [1] the later
>>>>>> with the call to software_node_notify(KOBJ_ADD) does seem to fix the
>>>>>> issue I'm seeing.
>>>>>>
>>>>>> Could this be a problem? Any comments appreciated.
>>>>>>
>>>>>> One more thing perhaps worth mentioning is that, at least for now, there
>>>>>> are few uses for this device_create_managed_software_node() api,
>>>>>> mentioning here a couple of them:
>>>>>> - arm64 iort code - this seems to be triggering the issue i'm getting
>>>>>> - dwc3 usb - Andy reported similar issues here, maybe the issue is common?
>>>>>>
>>>>>> [1]
>>>>>> @@ -1113,6 +1125,15 @@ int device_create_managed_software_node(struct
>>>>>> device *dev,
>>>>>> to_swnode(fwnode)->managed = true;
>>>>>> set_secondary_fwnode(dev, fwnode);
>>>>>>
>>>>>> + /*
>>>>>> + * If the device has been fully registered by the time this
>>>>>> function is
>>>>>> + * called, software_node_notify() must be called separately so
>>>>>> that the
>>>>>> + * symlinks get created and the reference count of the node is
>>>>>> kept in
>>>>>> + * balance.
>>>>>> + */
>>>>>> + if (device_is_registered(dev))
>>>>>> + software_node_notify(dev, KOBJ_ADD);
>>>>>> +
>>>>>> return 0;
>>>>>> }
>>>>>
>>>>> That should be fixed indeed. Please send that after -rc1 is out.
>>>>
>>>> I mean, resend :-)
>>>>
>>>
>>> Right, actually I just noticed that this is the fix you suggested last
>>> time we discussed. :-) I forgot about it, sorry.
>>> There's still the WARN_ON() [1] triggered by the usb subsys, apparently
>>> happening only (!) in ACPI boot scenario, so +Lorenzo.
>>> I'll delay the sending a bit to try to understand what's going on.
>>
>> I've spent some time looking into this and it turns out that in the
>> ACPI case, device_create_managed_software_node() ends up being called
>> twice, first here [1] and after that, in the IORT code here [2]. With
>> the proposed patch this causes software_node_notify(KOBJ_ADD) being
>> called twice thus triggering the dup sysfs entry warning.
>> Any comments / ideas welcomed.
>>
>> [1] https://elixir.bootlin.com/linux/latest/source/drivers/usb/dwc3/host.c#L111
>
> I think the problem here is that the secondary fwnode get's replaced
> because the primary fwnode is shared. Can you test it with this, just
> to see if the problem goes away:
>
> diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> index f29a264635aa1..e4b40f8b8f242 100644
> --- a/drivers/usb/dwc3/host.c
> +++ b/drivers/usb/dwc3/host.c
> @@ -76,7 +76,6 @@ int dwc3_host_init(struct dwc3 *dwc)
> }
>
> xhci->dev.parent = dwc->dev;
> - ACPI_COMPANION_SET(&xhci->dev, ACPI_COMPANION(dwc->dev));
>
> dwc->xhci = xhci;
Thanks for looking into this! Yes, this does make the issue go away.
---
Best Regards, Laurentiu
On Fri, Jul 16, 2021 at 01:16:02PM +0300, [email protected] wrote:
> From: Laurentiu Tudor <[email protected]>
>
> software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed
> software nodes, thus leading to underflow errors. Balance the refcount by
> bumping it in the device_create_managed_software_node() function.
>
> The error [1] was encountered after adding a .shutdown() op to our
> fsl-mc-bus driver.
>
> [1]
> pc : refcount_warn_saturate+0xf8/0x150
> lr : refcount_warn_saturate+0xf8/0x150
> sp : ffff80001009b920
> x29: ffff80001009b920 x28: ffff1a2420318000 x27: 0000000000000000
> x26: ffffccac15e7a038 x25: 0000000000000008 x24: ffffccac168e0030
> x23: ffff1a2428a82000 x22: 0000000000080000 x21: ffff1a24287b5000
> x20: 0000000000000001 x19: ffff1a24261f4400 x18: ffffffffffffffff
> x17: 6f72645f726f7272 x16: 0000000000000000 x15: ffff80009009b607
> x14: 0000000000000000 x13: ffffccac16602670 x12: 0000000000000a17
> x11: 000000000000035d x10: ffffccac16602670 x9 : ffffccac16602670
> x8 : 00000000ffffefff x7 : ffffccac1665a670 x6 : ffffccac1665a670
> x5 : 0000000000000000 x4 : 0000000000000000 x3 : 00000000ffffffff
> x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff1a2420318000
> Call trace:
> refcount_warn_saturate+0xf8/0x150
> kobject_put+0x10c/0x120
> software_node_notify+0xd8/0x140
> device_platform_notify+0x4c/0xb4
> device_del+0x188/0x424
> fsl_mc_device_remove+0x2c/0x4c
> rebofind sp.c__fsl_mc_device_remove+0x14/0x2c
> device_for_each_child+0x5c/0xac
> dprc_remove+0x9c/0xc0
> fsl_mc_driver_remove+0x28/0x64
> __device_release_driver+0x188/0x22c
> device_release_driver+0x30/0x50
> bus_remove_device+0x128/0x134
> device_del+0x16c/0x424
> fsl_mc_bus_remove+0x8c/0x114
> fsl_mc_bus_shutdown+0x14/0x20
> platform_shutdown+0x28/0x40
> device_shutdown+0x15c/0x330
> __do_sys_reboot+0x218/0x2a0
> __arm64_sys_reboot+0x28/0x34
> invoke_syscall+0x48/0x114
> el0_svc_common+0x40/0xdc
> do_el0_svc+0x2c/0x94
> el0_svc+0x2c/0x54
> el0t_64_sync_handler+0xa8/0x12c
> el0t_64_sync+0x198/0x19c
> ---[ end trace 32eb1c71c7d86821 ]---
>
> Reported-by: Jon Nettleton <[email protected]>
> Suggested-by: Heikki Krogerus <[email protected]>
> Signed-off-by: Laurentiu Tudor <[email protected]>
FWIW:
Reviewed-by: Heikki Krogerus <[email protected]>
> ---
> Changes since RFC:
> - use software_node_notify(KOBJ_ADD) instead of directly bumping
> refcount (Heikki)
>
> drivers/base/swnode.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
> index d1f1a8240120..bdb50a06c82a 100644
> --- a/drivers/base/swnode.c
> +++ b/drivers/base/swnode.c
> @@ -1113,6 +1113,9 @@ int device_create_managed_software_node(struct device *dev,
> to_swnode(fwnode)->managed = true;
> set_secondary_fwnode(dev, fwnode);
>
> + if (device_is_registered(dev))
> + software_node_notify(dev, KOBJ_ADD);
> +
> return 0;
> }
> EXPORT_SYMBOL_GPL(device_create_managed_software_node);
> --
> 2.17.1
thanks,
--
heikki
On Fri, Sep 10, 2021 at 04:00:49PM +0300, Laurentiu Tudor wrote:
> >> I've spent some time looking into this and it turns out that in the
> >> ACPI case, device_create_managed_software_node() ends up being called
> >> twice, first here [1] and after that, in the IORT code here [2]. With
> >> the proposed patch this causes software_node_notify(KOBJ_ADD) being
> >> called twice thus triggering the dup sysfs entry warning.
> >> Any comments / ideas welcomed.
> >>
> >> [1] https://elixir.bootlin.com/linux/latest/source/drivers/usb/dwc3/host.c#L111
> >
> > I think the problem here is that the secondary fwnode get's replaced
> > because the primary fwnode is shared. Can you test it with this, just
> > to see if the problem goes away:
> >
> > diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> > index f29a264635aa1..e4b40f8b8f242 100644
> > --- a/drivers/usb/dwc3/host.c
> > +++ b/drivers/usb/dwc3/host.c
> > @@ -76,7 +76,6 @@ int dwc3_host_init(struct dwc3 *dwc)
> > }
> >
> > xhci->dev.parent = dwc->dev;
> > - ACPI_COMPANION_SET(&xhci->dev, ACPI_COMPANION(dwc->dev));
> >
> > dwc->xhci = xhci;
>
>
> Thanks for looking into this! Yes, this does make the issue go away.
We need to think about how to solve this one. The problem is that we
have to share the ACPI node between the parent dwc3 device and child
xHCI, but at the same xHCI needs to have its own software node.
The fwnode->secondary pointer does not quite bend to this. If the
primary fwnode is shared, the secondary fwnode has to be shared as
well.
thanks,
--
heikki