| Message ID | 20201006041214.GA4145870@dtor-ws (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [v2] iio: adc: exynos: do not rely on 'users' counter in ISR | expand |
On Tue, 6 Oct 2020 at 06:12, <dmitry.torokhov@gmail.com> wrote: > > The order in which 'users' counter is decremented vs calling drivers' > close() method is implementation specific, and we should not rely on > it. Let's introduce driver private flag and use it to signal ISR > to exit when device is being closed. > > This has a side-effect of fixing issue of accessing inut->users > outside of input->mutex protection. > > Reported-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > --- > > v2: switched from ordinary read/write to READ_ONCE/WRITE_ONCE per Michał > Mirosław > > drivers/iio/adc/exynos_adc.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) Acked-by: Krzysztof Kozlowski <krzk@kernel.org> Best regards, Krzysztof
On Mon, Oct 05, 2020 at 09:12:14PM -0700, dmitry.torokhov@gmail.com wrote: > The order in which 'users' counter is decremented vs calling drivers' > close() method is implementation specific, and we should not rely on > it. Let's introduce driver private flag and use it to signal ISR > to exit when device is being closed. > > This has a side-effect of fixing issue of accessing inut->users > outside of input->mutex protection. [...] Reviewed-by: Michał Mirosław <mirq-linux@rere.qmqm.pl> (after with a fix mentioned below) > --- a/drivers/iio/adc/exynos_adc.c > +++ b/drivers/iio/adc/exynos_adc.c [...] > @@ -712,6 +715,7 @@ static int exynos_adc_ts_open(struct input_dev *dev) > { > struct exynos_adc *info = input_get_drvdata(dev); > > + WRITE_ONCE(info->ts_enabled, true); > enable_irq(info->tsirq); > > return 0; > @@ -721,6 +725,7 @@ static void exynos_adc_ts_close(struct input_dev *dev) > { > struct exynos_adc *info = input_get_drvdata(dev); > > + WRITE_ONCE(info->ts_enabled, true); > disable_irq(info->tsirq); Shouldn't 'true' be 'false' here? Best Regards, Michał Mirosław
On Tue, Oct 06, 2020 at 09:39:07PM +0200, Michał Mirosław wrote: > On Mon, Oct 05, 2020 at 09:12:14PM -0700, dmitry.torokhov@gmail.com wrote: > > The order in which 'users' counter is decremented vs calling drivers' > > close() method is implementation specific, and we should not rely on > > it. Let's introduce driver private flag and use it to signal ISR > > to exit when device is being closed. > > > > This has a side-effect of fixing issue of accessing inut->users > > outside of input->mutex protection. > [...] > > Reviewed-by: Michał Mirosław <mirq-linux@rere.qmqm.pl> > (after with a fix mentioned below) > > > --- a/drivers/iio/adc/exynos_adc.c > > +++ b/drivers/iio/adc/exynos_adc.c > [...] > > @@ -712,6 +715,7 @@ static int exynos_adc_ts_open(struct input_dev *dev) > > { > > struct exynos_adc *info = input_get_drvdata(dev); > > > > + WRITE_ONCE(info->ts_enabled, true); > > enable_irq(info->tsirq); > > > > return 0; > > @@ -721,6 +725,7 @@ static void exynos_adc_ts_close(struct input_dev *dev) > > { > > struct exynos_adc *info = input_get_drvdata(dev); > > > > + WRITE_ONCE(info->ts_enabled, true); > > disable_irq(info->tsirq); > > Shouldn't 'true' be 'false' here? I swear if we disable cut-n-paste functionality there will be markable reduction in bug rates... Thanks for noticing this!
diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c index 22131a677445..6c705fe599a3 100644 --- a/drivers/iio/adc/exynos_adc.c +++ b/drivers/iio/adc/exynos_adc.c @@ -7,6 +7,7 @@ * Copyright (C) 2013 Naveen Krishna Chatradhi <ch.naveen@samsung.com> */ +#include <linux/compiler.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/interrupt.h> @@ -135,6 +136,8 @@ struct exynos_adc { u32 value; unsigned int version; + bool ts_enabled; + bool read_ts; u32 ts_x; u32 ts_y; @@ -633,7 +636,7 @@ static irqreturn_t exynos_ts_isr(int irq, void *dev_id) bool pressed; int ret; - while (info->input->users) { + while (READ_ONCE(info->ts_enabled)) { ret = exynos_read_s3c64xx_ts(dev, &x, &y); if (ret == -ETIMEDOUT) break; @@ -712,6 +715,7 @@ static int exynos_adc_ts_open(struct input_dev *dev) { struct exynos_adc *info = input_get_drvdata(dev); + WRITE_ONCE(info->ts_enabled, true); enable_irq(info->tsirq); return 0; @@ -721,6 +725,7 @@ static void exynos_adc_ts_close(struct input_dev *dev) { struct exynos_adc *info = input_get_drvdata(dev); + WRITE_ONCE(info->ts_enabled, true); disable_irq(info->tsirq); }
The order in which 'users' counter is decremented vs calling drivers' close() method is implementation specific, and we should not rely on it. Let's introduce driver private flag and use it to signal ISR to exit when device is being closed. This has a side-effect of fixing issue of accessing inut->users outside of input->mutex protection. Reported-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> --- v2: switched from ordinary read/write to READ_ONCE/WRITE_ONCE per Michał Mirosław drivers/iio/adc/exynos_adc.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)