[PATCH 08/10] ACPI: EC: Avoid queuing unnecessary work in acpi_ec_submit_event()

Rafael J. Wysocki
2021-11-23T18:49:22Z

Notice that it is not necessary to queue up the event work again
if the while () loop in acpi_ec_event_handler() is still running
which is the case if nr_pending_queries is greater than 0 at the
beginning of acpi_ec_submit_event() and modify the code to avoid
doing that.

While at it, rename nr_pending_queries in struct acpi_ec to
events_to_process which actually matches the role of that field
and change its data type to unsigned int which is sufficient.

No expected functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/acpi/ec.c | 17 +++++++++++++----
drivers/acpi/internal.h | 2 +-
2 files changed, 14 insertions(+), 5 deletions(-)

Index: linux-pm/drivers/acpi/internal.h
===================================================================
--- linux-pm.orig/drivers/acpi/internal.h
+++ linux-pm/drivers/acpi/internal.h
@@ -183,7 +183,7 @@ struct acpi_ec {
spinlock_t lock;
struct work_struct work;
unsigned long timestamp;
- unsigned long nr_pending_queries;
+ unsigned int events_to_process;
unsigned int events_in_progress;
unsigned int queries_in_progress;
bool busy_polling;
Index: linux-pm/drivers/acpi/ec.c
===================================================================
--- linux-pm.orig/drivers/acpi/ec.c
+++ linux-pm/drivers/acpi/ec.c
@@ -453,7 +453,16 @@ static bool acpi_ec_submit_event(struct
if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
ec_dbg_evt("Command(%s) submitted/blocked",
acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
- ec->nr_pending_queries++;
+ /*
+ * If events_to_process is greqter than 0 at this point, the
+ * while () loop in acpi_ec_event_handler() is still running
+ * and incrementing events_to_process will cause it to invoke
+ * acpi_ec_submit_query() once more, so it is not necessary to
+ * queue up the event work to start the same loop again.
+ */
+ if (ec->events_to_process++ > 0)
+ return true;
+
ec->events_in_progress++;
return queue_work(ec_wq, &ec->work);
}
@@ -665,7 +674,7 @@ static bool advance_transaction(struct a
*/
if (!t || !(t->flags & ACPI_EC_COMMAND_POLL)) {
if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT &&
- (!ec->nr_pending_queries ||
+ (!ec->events_to_process ||
test_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags))) {
clear_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags);
acpi_ec_close_event(ec);
@@ -1223,13 +1232,13 @@ static void acpi_ec_event_handler(struct

spin_lock_irq(&ec->lock);

- while (ec->nr_pending_queries) {
+ while (ec->events_to_process) {
spin_unlock_irq(&ec->lock);

acpi_ec_submit_query(ec);

spin_lock_irq(&ec->lock);
- ec->nr_pending_queries--;
+ ec->events_to_process--;
}

/*