On Fri, Feb 02, 2018 at 09:43:20PM +0200, Andy Shevchenko wrote:
> +Cc: Dmitry
>
> On Fri, Feb 2, 2018 at 6:05 PM, 张波 <[email protected]> wrote:
> >
> > in matrix_keypad.c, the function disable_row_irqs() may be called by
> > matrix_keypad_interrupt() or matrix_keypad_stop(), there is race condition
> > to disble irqs.
> >
> >
> > If while matrix_keypad_stop() is calling, and the keypad interrupt is
> > triggered, disable_row_irqs() is called by matrix_keypad_interrupt() and
> > matrix_keypad_stop() at the same time. then disable_row_irqs() is called
> > twice, and the device enter suspend state before keypad->work is executed.
> > At this condition the device will start keypad and enable irq once after
> > resume. and irqs are disabled yet because irqs are disabled twice and only
> > enable once.
> > then the device can't trigger keypad interrupts.
> > this problem could reproduce easily by change code to add time delay in
> > matrix_keypad_interrupt() just before calling schedule_delayed_work.
> >
>
> Thanks for the patch.
>
> First of all, fix your email handlers. The patch is mangled quite badly.
>
> Second, follow the process [1] and don't forget to put your
> Signed-off-by tag (hint `git commit -a -s`).
>
> [1]:
> http://elixir.free-electrons.com/linux/latest/source/Documentation/process/submit-checklist.rst
Also, I do not think we need a new flag, simply taking the lock around
"keypad->stopped = true" in matrix_keypad_stop() instead of trying to
rely on mb() should fix the issue, as this will ensure that disabling
interrupts and scheduling the scan works as an atomic operation.
>
> >
> > diff --git a/drivers/input/keyboard/matrix_keypad.c
> > b/drivers/input/keyboard/matrix_keypad.c
> > index 1f316d66e6f7..03224ae9eedb 100644
> > --- a/drivers/input/keyboard/matrix_keypad.c
> > +++ b/drivers/input/keyboard/matrix_keypad.c
> > @@ -36,6 +36,7 @@ struct matrix_keypad {
> > uint32_t last_key_state[MATRIX_MAX_COLS];
> > struct delayed_work work;
> > spinlock_t lock;
> > + int irq_enabled;
> > bool scan_pending;
> > bool stopped;
> > bool gpio_all_disabled;
> > @@ -90,6 +91,12 @@ static void enable_row_irqs(struct matrix_keypad *keypad)
> > {
> > const struct matrix_keypad_platform_data *pdata = keypad->pdata;
> > int i;
> > + unsigned long flags;
> > +
> > + spin_lock_irqsave(&keypad->lock, flags);
> > +
> > + if (keypad->irq_enabled == 1)
> > + goto out;
> >
> > if (pdata->clustered_irq > 0)
> > enable_irq(pdata->clustered_irq);
> > @@ -97,19 +104,31 @@ static void enable_row_irqs(struct matrix_keypad
> > *keypad)
> > for (i = 0; i < pdata->num_row_gpios; i++)
> > enable_irq(gpio_to_irq(pdata->row_gpios[i]));
> > }
> > + keypad->irq_enabled = 1;
> > +
> > +out:
> > + spin_unlock_irqrestore(&keypad->lock, flags);
> > }
> >
> > static void disable_row_irqs(struct matrix_keypad *keypad)
> > {
> > const struct matrix_keypad_platform_data *pdata = keypad->pdata;
> > int i;
> > + unsigned long flags;
> >
> > + spin_lock_irqsave(&keypad->lock, flags);
> > + if (keypad->irq_enabled == 0)
> > + goto out;
> > if (pdata->clustered_irq > 0)
> > disable_irq_nosync(pdata->clustered_irq);
> > else {
> > for (i = 0; i < pdata->num_row_gpios; i++)
> > disable_irq_nosync(gpio_to_irq(pdata->row_gpios[i]));
> > }
> > + keypad->irq_enabled = 0;
> > +
> > +out:
> > + spin_unlock_irqrestore(&keypad->lock, flags);
> > }
> >
> > /*
> > @@ -167,18 +186,13 @@ static void matrix_keypad_scan(struct work_struct
> > *work)
> > activate_all_cols(pdata, true);
> >
> > /* Enable IRQs again */
> > - spin_lock_irq(&keypad->lock);
> > keypad->scan_pending = false;
> > enable_row_irqs(keypad);
> > - spin_unlock_irq(&keypad->lock);
> > }
> >
> > static irqreturn_t matrix_keypad_interrupt(int irq, void *id)
> > {
> > struct matrix_keypad *keypad = id;
> > - unsigned long flags;
> > -
> > - spin_lock_irqsave(&keypad->lock, flags);
You really need to take the lock here, since if you are not using
"clustered" interrupt, your interrupt routines may run simultaneously,
which you do not want.
> >
> > /*
> > * See if another IRQ beaten us to it and scheduled the
> > @@ -194,7 +208,6 @@ static irqreturn_t matrix_keypad_interrupt(int irq,
> > void *id)
> > msecs_to_jiffies(keypad->pdata->debounce_ms));
> >
> > out:
> > - spin_unlock_irqrestore(&keypad->lock, flags);
> > return IRQ_HANDLED;
> > }
>
>
>
> --
> With Best Regards,
> Andy Shevchenko
Thanks.
--
Dmitry
