From 1033be58992f818dc564196ded2bcc3f360bc297 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 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 --- drivers/gpio/gpiolib.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 1651d7f0a303..d1adfdf50fb3 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -828,7 +828,14 @@ 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; if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE && le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {