* [PATCH] software node: balance refcount for managed sw nodes @ 2021-07-16 10:16 laurentiu.tudor 2021-07-16 10:34 ` Laurentiu Tudor ` (2 more replies) 0 siblings, 3 replies; 18+ messages in thread From: laurentiu.tudor @ 2021-07-16 10:16 UTC (permalink / raw) To: andriy.shevchenko, heikki.krogerus, gregkh, rafael, linux-acpi, linux-kernel Cc: jon, Laurentiu Tudor From: Laurentiu Tudor <laurentiu.tudor@nxp.com> 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 <jon@solid-run.com> Suggested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com> --- 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 ^ permalink raw reply related [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-07-16 10:16 [PATCH] software node: balance refcount for managed sw nodes laurentiu.tudor @ 2021-07-16 10:34 ` Laurentiu Tudor 2021-07-16 12:17 ` Andy Shevchenko 2021-09-14 14:00 ` Heikki Krogerus 2 siblings, 0 replies; 18+ messages in thread From: Laurentiu Tudor @ 2021-07-16 10:34 UTC (permalink / raw) To: andriy.shevchenko, heikki.krogerus, gregkh, rafael, linux-acpi, linux-kernel Cc: jon 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, laurentiu.tudor@nxp.com wrote: > From: Laurentiu Tudor <laurentiu.tudor@nxp.com> > > 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 <jon@solid-run.com> > Suggested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> > Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com> > --- > 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); > ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-07-16 10:16 [PATCH] software node: balance refcount for managed sw nodes laurentiu.tudor 2021-07-16 10:34 ` Laurentiu Tudor @ 2021-07-16 12:17 ` Andy Shevchenko 2021-07-16 17:21 ` Jon Nettleton 2021-09-14 14:00 ` Heikki Krogerus 2 siblings, 1 reply; 18+ messages in thread From: Andy Shevchenko @ 2021-07-16 12:17 UTC (permalink / raw) To: laurentiu.tudor Cc: heikki.krogerus, gregkh, rafael, linux-acpi, linux-kernel, jon On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: > From: Laurentiu Tudor <laurentiu.tudor@nxp.com> > > 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-07-16 12:17 ` Andy Shevchenko @ 2021-07-16 17:21 ` Jon Nettleton 2021-07-19 12:00 ` Laurentiu Tudor 0 siblings, 1 reply; 18+ messages in thread From: Jon Nettleton @ 2021-07-16 17:21 UTC (permalink / raw) To: Andy Shevchenko Cc: Laurentiu Tudor, Heikki Krogerus, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote: > > On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: > > From: Laurentiu Tudor <laurentiu.tudor@nxp.com> > > > > 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-07-16 17:21 ` Jon Nettleton @ 2021-07-19 12:00 ` Laurentiu Tudor 2021-07-19 12:22 ` Andy Shevchenko 0 siblings, 1 reply; 18+ messages in thread From: Laurentiu Tudor @ 2021-07-19 12:00 UTC (permalink / raw) To: Jon Nettleton, Andy Shevchenko Cc: Heikki Krogerus, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List On 7/16/2021 8:21 PM, Jon Nettleton wrote: > On Fri, Jul 16, 2021 at 2:17 PM Andy Shevchenko > <andriy.shevchenko@linux.intel.com> wrote: >> >> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: >>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> >>> >>> 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-07-19 12:00 ` Laurentiu Tudor @ 2021-07-19 12:22 ` Andy Shevchenko 2021-07-20 9:20 ` Laurentiu Tudor 0 siblings, 1 reply; 18+ messages in thread From: Andy Shevchenko @ 2021-07-19 12:22 UTC (permalink / raw) To: Laurentiu Tudor Cc: Jon Nettleton, Heikki Krogerus, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List 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 > > <andriy.shevchenko@linux.intel.com> wrote: > >> > >> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: > >>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> > >>> > >>> 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-07-19 12:22 ` Andy Shevchenko @ 2021-07-20 9:20 ` Laurentiu Tudor 2021-07-20 10:27 ` Andy Shevchenko 0 siblings, 1 reply; 18+ messages in thread From: Laurentiu Tudor @ 2021-07-20 9:20 UTC (permalink / raw) To: Andy Shevchenko Cc: Jon Nettleton, Heikki Krogerus, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List 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 >>> <andriy.shevchenko@linux.intel.com> wrote: >>>> >>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: >>>>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> >>>>> >>>>> 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-07-20 9:20 ` Laurentiu Tudor @ 2021-07-20 10:27 ` Andy Shevchenko 2021-07-26 7:59 ` Laurentiu Tudor 0 siblings, 1 reply; 18+ messages in thread From: Andy Shevchenko @ 2021-07-20 10:27 UTC (permalink / raw) To: Laurentiu Tudor Cc: Andy Shevchenko, Jon Nettleton, Heikki Krogerus, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List On Tue, Jul 20, 2021 at 12:22 PM Laurentiu Tudor <laurentiu.tudor@nxp.com> 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 > >>> <andriy.shevchenko@linux.intel.com> wrote: > >>>> > >>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: > >>>>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> > >>>>> > >>>>> 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/c3c75895-313a-5be7-6421-b32bac741a88@arm.com/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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-07-20 10:27 ` Andy Shevchenko @ 2021-07-26 7:59 ` Laurentiu Tudor 2021-09-07 15:59 ` Laurentiu Tudor 0 siblings, 1 reply; 18+ messages in thread From: Laurentiu Tudor @ 2021-07-26 7:59 UTC (permalink / raw) To: Andy Shevchenko Cc: Andy Shevchenko, Jon Nettleton, Heikki Krogerus, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List On 7/20/2021 1:27 PM, Andy Shevchenko wrote: > On Tue, Jul 20, 2021 at 12:22 PM Laurentiu Tudor > <laurentiu.tudor@nxp.com> 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 >>>>> <andriy.shevchenko@linux.intel.com> wrote: >>>>>> >>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: >>>>>>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> >>>>>>> >>>>>>> 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-07-26 7:59 ` Laurentiu Tudor @ 2021-09-07 15:59 ` Laurentiu Tudor 2021-09-09 12:13 ` Heikki Krogerus 0 siblings, 1 reply; 18+ messages in thread From: Laurentiu Tudor @ 2021-09-07 15:59 UTC (permalink / raw) To: Andy Shevchenko Cc: Andy Shevchenko, Jon Nettleton, Heikki Krogerus, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List 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 >> <laurentiu.tudor@nxp.com> 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 >>>>>> <andriy.shevchenko@linux.intel.com> wrote: >>>>>>> >>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: >>>>>>>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> >>>>>>>> >>>>>>>> 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-09-07 15:59 ` Laurentiu Tudor @ 2021-09-09 12:13 ` Heikki Krogerus 2021-09-09 12:16 ` Heikki Krogerus 0 siblings, 1 reply; 18+ messages in thread From: Heikki Krogerus @ 2021-09-09 12:13 UTC (permalink / raw) To: Laurentiu Tudor Cc: Andy Shevchenko, Andy Shevchenko, Jon Nettleton, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List 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 > >> <laurentiu.tudor@nxp.com> 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 > >>>>>> <andriy.shevchenko@linux.intel.com> wrote: > >>>>>>> > >>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: > >>>>>>>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> > >>>>>>>> > >>>>>>>> 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-09-09 12:13 ` Heikki Krogerus @ 2021-09-09 12:16 ` Heikki Krogerus 2021-09-09 14:01 ` Laurentiu Tudor 0 siblings, 1 reply; 18+ messages in thread From: Heikki Krogerus @ 2021-09-09 12:16 UTC (permalink / raw) To: Laurentiu Tudor Cc: Andy Shevchenko, Andy Shevchenko, Jon Nettleton, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List 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 > > >> <laurentiu.tudor@nxp.com> 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 > > >>>>>> <andriy.shevchenko@linux.intel.com> wrote: > > >>>>>>> > > >>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: > > >>>>>>>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> > > >>>>>>>> > > >>>>>>>> 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-09-09 12:16 ` Heikki Krogerus @ 2021-09-09 14:01 ` Laurentiu Tudor 2021-09-10 12:05 ` Laurentiu Tudor 0 siblings, 1 reply; 18+ messages in thread From: Laurentiu Tudor @ 2021-09-09 14:01 UTC (permalink / raw) To: Heikki Krogerus Cc: Andy Shevchenko, Andy Shevchenko, Jon Nettleton, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List, Lorenzo Pieralisi 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 >>>>> <laurentiu.tudor@nxp.com> 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 >>>>>>>>> <andriy.shevchenko@linux.intel.com> wrote: >>>>>>>>>> >>>>>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: >>>>>>>>>>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> >>>>>>>>>>> >>>>>>>>>>> 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-09-09 14:01 ` Laurentiu Tudor @ 2021-09-10 12:05 ` Laurentiu Tudor 2021-09-10 12:38 ` Heikki Krogerus 0 siblings, 1 reply; 18+ messages in thread From: Laurentiu Tudor @ 2021-09-10 12:05 UTC (permalink / raw) To: Heikki Krogerus Cc: Andy Shevchenko, Andy Shevchenko, Jon Nettleton, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List, Lorenzo Pieralisi 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 >>>>>> <laurentiu.tudor@nxp.com> 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 >>>>>>>>>> <andriy.shevchenko@linux.intel.com> wrote: >>>>>>>>>>> >>>>>>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: >>>>>>>>>>>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> >>>>>>>>>>>> >>>>>>>>>>>> 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-09-10 12:05 ` Laurentiu Tudor @ 2021-09-10 12:38 ` Heikki Krogerus 2021-09-10 13:00 ` Laurentiu Tudor 0 siblings, 1 reply; 18+ messages in thread From: Heikki Krogerus @ 2021-09-10 12:38 UTC (permalink / raw) To: Laurentiu Tudor Cc: Andy Shevchenko, Andy Shevchenko, Jon Nettleton, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List, Lorenzo Pieralisi 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 > >>>>>> <laurentiu.tudor@nxp.com> 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 > >>>>>>>>>> <andriy.shevchenko@linux.intel.com> wrote: > >>>>>>>>>>> > >>>>>>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: > >>>>>>>>>>>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> > >>>>>>>>>>>> > >>>>>>>>>>>> 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 ^ permalink raw reply related [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-09-10 12:38 ` Heikki Krogerus @ 2021-09-10 13:00 ` Laurentiu Tudor 2021-09-14 14:13 ` Heikki Krogerus 0 siblings, 1 reply; 18+ messages in thread From: Laurentiu Tudor @ 2021-09-10 13:00 UTC (permalink / raw) To: Heikki Krogerus Cc: Andy Shevchenko, Andy Shevchenko, Jon Nettleton, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List, Lorenzo Pieralisi 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 >>>>>>>> <laurentiu.tudor@nxp.com> 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 >>>>>>>>>>>> <andriy.shevchenko@linux.intel.com> wrote: >>>>>>>>>>>>> >>>>>>>>>>>>> On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: >>>>>>>>>>>>>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com> >>>>>>>>>>>>>> >>>>>>>>>>>>>> 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-09-10 13:00 ` Laurentiu Tudor @ 2021-09-14 14:13 ` Heikki Krogerus 0 siblings, 0 replies; 18+ messages in thread From: Heikki Krogerus @ 2021-09-14 14:13 UTC (permalink / raw) To: Laurentiu Tudor Cc: Andy Shevchenko, Andy Shevchenko, Jon Nettleton, Greg Kroah-Hartman, Rafael J . Wysocki, ACPI Devel Maling List, Linux Kernel Mailing List, Lorenzo Pieralisi 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] software node: balance refcount for managed sw nodes 2021-07-16 10:16 [PATCH] software node: balance refcount for managed sw nodes laurentiu.tudor 2021-07-16 10:34 ` Laurentiu Tudor 2021-07-16 12:17 ` Andy Shevchenko @ 2021-09-14 14:00 ` Heikki Krogerus 2 siblings, 0 replies; 18+ messages in thread From: Heikki Krogerus @ 2021-09-14 14:00 UTC (permalink / raw) To: laurentiu.tudor Cc: andriy.shevchenko, gregkh, rafael, linux-acpi, linux-kernel, jon On Fri, Jul 16, 2021 at 01:16:02PM +0300, laurentiu.tudor@nxp.com wrote: > From: Laurentiu Tudor <laurentiu.tudor@nxp.com> > > 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 <jon@solid-run.com> > Suggested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> > Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com> FWIW: Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> > --- > 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 ^ permalink raw reply [flat|nested] 18+ messages in thread
end of thread, other threads:[~2021-09-14 14:13 UTC | newest] Thread overview: 18+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-07-16 10:16 [PATCH] software node: balance refcount for managed sw nodes laurentiu.tudor 2021-07-16 10:34 ` Laurentiu Tudor 2021-07-16 12:17 ` Andy Shevchenko 2021-07-16 17:21 ` Jon Nettleton 2021-07-19 12:00 ` Laurentiu Tudor 2021-07-19 12:22 ` Andy Shevchenko 2021-07-20 9:20 ` Laurentiu Tudor 2021-07-20 10:27 ` Andy Shevchenko 2021-07-26 7:59 ` Laurentiu Tudor 2021-09-07 15:59 ` Laurentiu Tudor 2021-09-09 12:13 ` Heikki Krogerus 2021-09-09 12:16 ` Heikki Krogerus 2021-09-09 14:01 ` Laurentiu Tudor 2021-09-10 12:05 ` Laurentiu Tudor 2021-09-10 12:38 ` Heikki Krogerus 2021-09-10 13:00 ` Laurentiu Tudor 2021-09-14 14:13 ` Heikki Krogerus 2021-09-14 14:00 ` Heikki Krogerus
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