Messages in this thread | | | Subject | Re: [PATCH RESEND v2 3/5] extcon: extcon-max77693.c: Fix potential work-queue cancellation race | From | Matti Vaittinen <> | Date | Thu, 10 Jun 2021 12:57:40 +0300 |
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On Thu, 2021-06-10 at 18:43 +0900, Chanwoo Choi wrote: > On 6/8/21 7:10 PM, Matti Vaittinen wrote: > > The extcon IRQ schedules a work item. IRQ is requested using devm > > while > > WQ is cancelld at remove(). This mixing of devm and manual > > unwinding has > > potential case where the WQ has been emptied (.remove() was ran) > > but > > devm unwinding of IRQ was not yet done. It may be possible the IRQ > > is > > triggered at this point scheduling new work item to the already > > flushed > > queue. > > > > According to the input documentation the input device allocated by > > devm_input_allocate_device() does not need to be explicitly > > unregistered. > > Use the new devm_work_autocancel() and remove the remove() to > > simplify the > > code. > > > > Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com> > > Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com > > > > > Reviewed-by: Hans de Goede <hdegoede@redhat.com> > > --- > > > > Please note that the change is compile-tested only. All proper > > testing is > > highly appreciated. > > --- > > drivers/extcon/extcon-max77693.c | 17 +++++------------ > > 1 file changed, 5 insertions(+), 12 deletions(-) > > > > diff --git a/drivers/extcon/extcon-max77693.c > > b/drivers/extcon/extcon-max77693.c > > index 92af97e00828..1f1d9ab0c5c7 100644 > > --- a/drivers/extcon/extcon-max77693.c > > +++ b/drivers/extcon/extcon-max77693.c > > @@ -5,6 +5,7 @@ > > // Copyright (C) 2012 Samsung Electrnoics > > // Chanwoo Choi <cw00.choi@samsung.com> > > > > +#include <linux/devm-helpers.h> > > #include <linux/kernel.h> > > #include <linux/module.h> > > #include <linux/i2c.h> > > @@ -1127,7 +1128,10 @@ static int max77693_muic_probe(struct > > platform_device *pdev) > > platform_set_drvdata(pdev, info); > > mutex_init(&info->mutex); > > > > - INIT_WORK(&info->irq_work, max77693_muic_irq_work); > > + ret = devm_work_autocancel(&pdev->dev, &info->irq_work, > > + max77693_muic_irq_work); > > + if (ret) > > + return ret; > > > > /* Support irq domain for MAX77693 MUIC device */ > > for (i = 0; i < ARRAY_SIZE(muic_irqs); i++) { > > @@ -1254,22 +1258,11 @@ static int max77693_muic_probe(struct > > platform_device *pdev) > > return ret; > > } > > > > -static int max77693_muic_remove(struct platform_device *pdev) > > -{ > > - struct max77693_muic_info *info = platform_get_drvdata(pdev); > > - > > - cancel_work_sync(&info->irq_work); > > - input_unregister_device(info->dock); > > I think that you have to keep the input_unregister_device().
Are you sure? I can add back the remove() if required - but the kerneldoc for devm_input_allocate_device() seems to be suggesting that this would not be needed:
* Managed input devices do not need to be explicitly unregistered or * freed as it will be done automatically when owner device unbinds from * its driver (or binding fails). Once managed input device is allocated, * it is ready to be set up and registered in the same fashion as regular * input device. There are no special devm_input_device_[un]register() * variants, regular ones work with both managed and unmanaged devices, * should you need them. In most cases however, managed input device need * not be explicitly unregistered or freed.
https://elixir.bootlin.com/linux/v5.13-rc5/source/drivers/input/input.c#L1955
I am not going to argue with you though - I am not really familiar with the input subsystem. I'd appreciate if someone could shed some light on when the input_unregister_device() can be omitted?
Best Regards Matti Vaittinen
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