diff options
Diffstat (limited to 'drivers/rtc/dev.c')
| -rw-r--r-- | drivers/rtc/dev.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/rtc/dev.c b/drivers/rtc/dev.c index baf1a8ca8b2b..8ba7c25d2565 100644 --- a/drivers/rtc/dev.c +++ b/drivers/rtc/dev.c @@ -195,7 +195,16 @@ static __poll_t rtc_dev_poll(struct file *file, poll_table *wait) poll_wait(file, &rtc->irq_queue, wait); - data = rtc->irq_data; + /* + * This read can race with the write in rtc_handle_legacy_irq(). + * + * - If this check misses a zero to non-zero transition the next check + * will pick it up (rtc_handle_legacy_irq() wakes up rtc->irq_queue). + * - Non-zero to non-zero transition misses do not change return value. + * - And a non-zero to zero transition is unlikely to be missed, since + * it occurs on rtc_dev_read(), during which polling is not expected. + */ + data = data_race(rtc->irq_data); return (data != 0) ? (EPOLLIN | EPOLLRDNORM) : 0; } |