Some processes, such as systemd, are only polling for EPOLLERR|EPOLLHUP.
As drm_file uses unkeyed wakeups, such a poll can receive many spurious
wakeups from uninteresting events if, for example, the file description
is subscribed to vblank events. This is the case with systemd, as it
polls a file description from logind that is shared with the users'
compositor.
Use keyed wakeups to allow the wakeup target to more efficiently discard
these uninteresting events.
Signed-off-by: Kenny Levinsen
---
drivers/gpu/drm/drm_file.c | 6 --
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index c4c704e01961..ec25b3d979d9 100644
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -608,7 +608,8 @@ ssize_t drm_read(struct file *filp, char __user *buffer,
file_priv->event_space -= length;
list_add(>link, _priv->event_list);
spin_unlock_irq(>event_lock);
- wake_up_interruptible(_priv->event_wait);
+
wake_up_interruptible_poll(_priv->event_wait,
+ EPOLLIN | EPOLLRDNORM);
break;
}
@@ -804,7 +805,8 @@ void drm_send_event_locked(struct drm_device *dev, struct
drm_pending_event *e)
list_del(>pending_link);
list_add_tail(>link,
>file_priv->event_list);
- wake_up_interruptible(>file_priv->event_wait);
+ wake_up_interruptible_poll(>file_priv->event_wait,
+ EPOLLIN | EPOLLRDNORM);
}
EXPORT_SYMBOL(drm_send_event_locked);
--
2.26.1
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