ACPI: EC: Call advance_transaction() from acpi_ec_dispatch_gpe()

Calling acpi_dispatch_gpe() from acpi_ec_dispatch_gpe() is generally
problematic, because it may cause the spurious interrupt handling in
advance_transaction() to trigger in theory.

However, instead of calling acpi_dispatch_gpe() to dispatch the EC
GPE, acpi_ec_dispatch_gpe() can call advance_transaction() directly
on first_ec and it can pass 'false' as its second argument to indicate
calling it from process context.

Moreover, if advance_transaction() is modified to return a bool value
indicating whether or not the EC work needs to be flushed, it can be
used to avoid unnecessary EC work flushing in acpi_ec_dispatch_gpe(),
so change the code accordingly.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index b9c44e6c5e400980b3608c404c79e62c5fab1788..bfc29cdfa5f067401d0cc70dd7a931732a6ac02f 100644 (file)
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -170,7 +170,7 @@ struct acpi_ec_query {
 };
 
 static int acpi_ec_query(struct acpi_ec *ec, u8 *data);
-static void advance_transaction(struct acpi_ec *ec, bool interrupt);
+static bool advance_transaction(struct acpi_ec *ec, bool interrupt);
 static void acpi_ec_event_handler(struct work_struct *work);
 static void acpi_ec_event_processor(struct work_struct *work);
 
@@ -444,18 +444,25 @@ static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec)
        return true;
 }
 
-static void acpi_ec_submit_query(struct acpi_ec *ec)
+static bool acpi_ec_submit_query(struct acpi_ec *ec)
 {
        acpi_ec_mask_events(ec);
        if (!acpi_ec_event_enabled(ec))
-               return;
+               return false;
+
        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++;
                ec->events_in_progress++;
-               queue_work(ec_wq, &ec->work);
+               return queue_work(ec_wq, &ec->work);
        }
+
+       /*
+        * The event handling work has not been completed yet, so it needs to be
+        * flushed.
+        */
+       return true;
 }
 
 static void acpi_ec_complete_query(struct acpi_ec *ec)
@@ -628,10 +635,11 @@ static void acpi_ec_spurious_interrupt(struct acpi_ec *ec, struct transaction *t
                acpi_ec_mask_events(ec);
 }
 
-static void advance_transaction(struct acpi_ec *ec, bool interrupt)
+static bool advance_transaction(struct acpi_ec *ec, bool interrupt)
 {
        struct transaction *t = ec->curr;
        bool wakeup = false;
+       bool ret = false;
        u8 status;
 
        ec_dbg_stm("%s (%d)", interrupt ? "IRQ" : "TASK", smp_processor_id());
@@ -698,10 +706,12 @@ static void advance_transaction(struct acpi_ec *ec, bool interrupt)
 
 out:
        if (status & ACPI_EC_FLAG_SCI)
-               acpi_ec_submit_query(ec);
+               ret = acpi_ec_submit_query(ec);
 
        if (wakeup && interrupt)
                wake_up(&ec->wait);
+
+       return ret;
 }
 
 static void start_transaction(struct acpi_ec *ec)
@@ -2038,8 +2048,7 @@ void acpi_ec_set_gpe_wake_mask(u8 action)
 
 bool acpi_ec_dispatch_gpe(void)
 {
-       bool work_in_progress;
-       u32 ret;
+       bool work_in_progress = false;
 
        if (!first_ec)
                return acpi_any_gpe_status_set(U32_MAX);
@@ -2055,9 +2064,17 @@ bool acpi_ec_dispatch_gpe(void)
         * Dispatch the EC GPE in-band, but do not report wakeup in any case
         * to allow the caller to process events properly after that.
         */
-       ret = acpi_dispatch_gpe(NULL, first_ec->gpe);
-       if (ret == ACPI_INTERRUPT_HANDLED)
-               pm_pr_dbg("ACPI EC GPE dispatched\n");
+       spin_lock_irq(&first_ec->lock);
+
+       if (acpi_ec_gpe_status_set(first_ec))
+               work_in_progress = advance_transaction(first_ec, false);
+
+       spin_unlock_irq(&first_ec->lock);
+
+       if (!work_in_progress)
+               return false;
+
+       pm_pr_dbg("ACPI EC GPE dispatched\n");
 
        /* Drain EC work. */
        do {