Subject: Re: [PATCH v4 4/7] ACPI: button: Use input_device_enabled() helper

From: Dmitry Torokhov <[email-masked]>
Date: Sun, 4 Oct 2020 22:06:42 -0700

On Wed, Jun 24, 2020 at 10:24:46PM -0700, Dmitry Torokhov wrote:
> On Mon, Jun 08, 2020 at 01:22:08PM +0200, Andrzej Pietrasiewicz wrote:
> > A new helper is available, so use it.
> > 
> > Signed-off-by: Andrzej Pietrasiewicz <[email-masked]>
> > ---
> >  drivers/acpi/button.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
> > index ff7ab291f678..4deb2b48d03c 100644
> > --- a/drivers/acpi/button.c
> > +++ b/drivers/acpi/button.c
> > @@ -411,7 +411,7 @@ static void acpi_button_notify(struct acpi_device *device, u32 event)
> >  		input = button->input;
> >  		if (button->type == ACPI_BUTTON_TYPE_LID) {
> >  			mutex_lock(&button->input->mutex);
> > -			users = button->input->users;
> > +			users = input_device_enabled(button->input);
> >  			mutex_unlock(&button->input->mutex);
> >  			if (users)
> 
> This chunk (pre-patch) is really wrong. 'users' value is obsolete and
> can not be trusted the moment we unlocked the mutex. "if" needs to be
> inside critical section.

So looking at this patch and the previous one again, I believe this
driver is wrong to key the behavior off input->users and we should not
apply either of the patches. I'll post another patch fixing this.

Thanks.

-- 
Dmitry

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