From: Bartosz Golaszewski bgolaszewski@baylibre.com

Nested interrupts run inside the calling thread's context and the top half handler is never called which means that we never read the timestamp.

This issue came up when trying to read line events from a gpiochip using regmap_irq_chip for interrupts.

Fix it by reading the timestamp from the irq thread function if it's still 0 by the time the second handler is called.

Fixes: d58f2bf261fd ("gpio: Timestamp events in hardirq handler") Cc: stable@vger.kernel.org Signed-off-by: Bartosz Golaszewski bgolaszewski@baylibre.com --- Hi Sasha,

this is a backport for v4.19.y series. The original patch didn't apply due to a conflict.

drivers/gpio/gpiolib.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index a8e01d99919c..b3ab6c428423 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -817,7 +817,15 @@ static irqreturn_t lineevent_irq_thread(int irq, void *p) /* Do not leak kernel stack to userspace */ memset(&ge, 0, sizeof(ge));

- ge.timestamp = le->timestamp; + /* + * We may be running from a nested threaded interrupt in which case + * we didn't get the timestamp from lineevent_irq_handler(). + */ + if (!le->timestamp) + ge.timestamp = ktime_get_real_ns(); + else + ge.timestamp = le->timestamp; + level = gpiod_get_value_cansleep(le->desc);

if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE