ACPI: EC: Avoid queuing unnecessary work in acpi_ec_submit_event()

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>

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 473b1d8617b58349d05ba71b3bed2faa4985529e..d578f41410efc1fa7d52a26df80f7abba8a736bd 100644 (file)
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -453,7 +453,16 @@ static bool acpi_ec_submit_event(struct acpi_ec *ec)
        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 acpi_ec *ec, bool interrupt)
         */
        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 work_struct *work)
 
        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--;
        }
 
        /*

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 54b2be94d23dcb0f00264c63c8ba1e3a37e82640..de546be3bc6a6b57ced2c85d39a5c30f2c90969d 100644 (file)
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -182,7 +182,7 @@ 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;