This patch introduces concept to drop partial events in evdev handler
itself after emptying the buffer which are dropped by all evdev
clients in userspace after SYN_DROPPED occurs.
This in turn saves space of partial events in evdev handler buffer
and reduces evdev client reading requests.
Signed-off-by: Aniroop Mathur <a.mat...@samsung.com>
---
drivers/input/evdev.c | 49 +++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 45 insertions(+), 4 deletions(-)
diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index e9ae3d5..e7b612e 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -58,6 +58,7 @@ struct evdev_client {
struct list_head node;
unsigned int clk_type;
bool revoked;
+ bool drop_pevent; /* specifies whether partial events need to be
dropped */
unsigned long *evmasks[EV_CNT];
unsigned int bufsize;
struct input_event buffer[];
@@ -192,6 +193,7 @@ static int evdev_set_clk_type(struct evdev_client *client,
unsigned int clkid)
{
unsigned long flags;
unsigned int clk_type;
+ struct input_event *ev;
switch (clkid) {
@@ -218,6 +220,17 @@ static int evdev_set_clk_type(struct evdev_client *client,
unsigned int clkid)
spin_lock_irqsave(&client->buffer_lock, flags);
if (client->head != client->tail) {
+
+ /*
+ * Set drop_pevent to true if last event packet is
+ * not stored completely in buffer.
+ */
+ client->head--;
+ client->head &= client->bufsize - 1;
+ ev = &client->buffer[client->head];
+ if (!(ev->type == EV_SYN && ev->code == SYN_REPORT))
+ client->drop_pevent = true;
+
client->packet_head = client->head = client->tail;
__evdev_queue_syn_dropped(client);
}
@@ -228,31 +241,51 @@ static int evdev_set_clk_type(struct evdev_client
*client, unsigned int clkid)
return 0;
}
-static void __pass_event(struct evdev_client *client,
+static bool __pass_event(struct evdev_client *client,
const struct input_event *event)
{
+ struct input_event *prev_ev;
+
client->buffer[client->head++] = *event;
client->head &= client->bufsize - 1;
if (unlikely(client->head == client->tail)) {
/*
- * This effectively "drops" all unconsumed events, leaving
- * EV_SYN/SYN_DROPPED plus the newest event in the queue.
+ * This effectively "drops" all unconsumed events, storing
+ * EV_SYN/SYN_DROPPED and the newest event in the queue but
+ * only if it is not part of partial packet.
+ * Set drop_pevent to true if last event packet is not stored
+ * completely in buffer and set to false if SYN_REPORT occurs.
*/
+
client->tail = (client->head - 2) & (client->bufsize - 1);
+ prev_ev = &client->buffer[client->tail];
+ if (!(prev_ev->type == EV_SYN && prev_ev->code == SYN_REPORT)) {
+ client->drop_pevent = true;
+ client->head--;
+ client->head &= client->bufsize - 1;
+ }
+
client->buffer[client->tail].time = event->time;
client->buffer[client->tail].type = EV_SYN;
client->buffer[client->tail].code = SYN_DROPPED;
client->buffer[client->tail].value = 0;
client->packet_head = client->tail;
+
+ if (event->type == EV_SYN && event->code == SYN_REPORT) {
+ client->drop_pevent = false;
+ return true;
+ }
}
if (event->type == EV_SYN && event->code == SYN_REPORT) {
client->packet_head = client->head;
kill_fasync(&client->fasync, SIGIO, POLL_IN);
}
+
+ return false;
}
static void evdev_pass_values(struct evdev_client *client,
@@ -284,10 +317,18 @@ static void evdev_pass_values(struct evdev_client *client,
wakeup = true;
}
+ /* drop partial events until SYN_REPORT occurs */
+ if (client->drop_pevent) {
+ if (v->type == EV_SYN && v->code == SYN_REPORT)
+ client->drop_pevent = false;
+ continue;
+ }
+
event.type = v->type;
event.code = v->code;
event.value = v->value;
- __pass_event(client, &event);
+ if (__pass_event(client, &event))
+ wakeup = false;
}
spin_unlock(&client->buffer_lock);
--
2.6.2
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