From 452ad274c926c8a84e320ebeedd54a38a9e0b08f Mon Sep 17 00:00:00 2001 From: Bartosz Golaszewski Date: Fri, 4 Jan 2019 11:24:20 +0100 Subject: [PATCH] gpiolib: fix line event timestamps for nested irqs commit 1033be58992f818dc564196ded2bcc3f360bc297 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- 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 a8e01d9..b3ab6c4 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 -- 2.7.4