ACPI / EC: Add reference counting for query handlers

This patch adds reference counting for query handlers in order to eliminate
kmalloc()/kfree() usage.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tested-by: Steffen Weber <steffen.weber@gmail.com>
Tested-by: Ortwin Glück <odi@odi.ch>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 3e19123..87b9911 100644 (file)
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -105,6 +105,7 @@ struct acpi_ec_query_handler {
        acpi_handle handle;
        void *data;
        u8 query_bit;
+       struct kref kref;
 };
 
 struct transaction {
@@ -580,6 +581,27 @@ static int acpi_ec_query_unlocked(struct acpi_ec *ec, u8 *data)
 /* --------------------------------------------------------------------------
                                 Event Management
    -------------------------------------------------------------------------- */
+static struct acpi_ec_query_handler *
+acpi_ec_get_query_handler(struct acpi_ec_query_handler *handler)
+{
+       if (handler)
+               kref_get(&handler->kref);
+       return handler;
+}
+
+static void acpi_ec_query_handler_release(struct kref *kref)
+{
+       struct acpi_ec_query_handler *handler =
+               container_of(kref, struct acpi_ec_query_handler, kref);
+
+       kfree(handler);
+}
+
+static void acpi_ec_put_query_handler(struct acpi_ec_query_handler *handler)
+{
+       kref_put(&handler->kref, acpi_ec_query_handler_release);
+}
+
 int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
                              acpi_handle handle, acpi_ec_query_func func,
                              void *data)
@@ -595,6 +617,7 @@ int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
        handler->func = func;
        handler->data = data;
        mutex_lock(&ec->mutex);
+       kref_init(&handler->kref);
        list_add(&handler->node, &ec->list);
        mutex_unlock(&ec->mutex);
        return 0;
@@ -604,15 +627,18 @@ EXPORT_SYMBOL_GPL(acpi_ec_add_query_handler);
 void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit)
 {
        struct acpi_ec_query_handler *handler, *tmp;
+       LIST_HEAD(free_list);
 
        mutex_lock(&ec->mutex);
        list_for_each_entry_safe(handler, tmp, &ec->list, node) {
                if (query_bit == handler->query_bit) {
-                       list_del(&handler->node);
-                       kfree(handler);
+                       list_del_init(&handler->node);
+                       list_add(&handler->node, &free_list);
                }
        }
        mutex_unlock(&ec->mutex);
+       list_for_each_entry(handler, &free_list, node)
+               acpi_ec_put_query_handler(handler);
 }
 EXPORT_SYMBOL_GPL(acpi_ec_remove_query_handler);
 
@@ -628,14 +654,14 @@ static void acpi_ec_run(void *cxt)
        else if (handler->handle)
                acpi_evaluate_object(handler->handle, NULL, NULL, NULL);
        pr_debug("##### Query(0x%02x) stopped #####\n", handler->query_bit);
-       kfree(handler);
+       acpi_ec_put_query_handler(handler);
 }
 
 static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data)
 {
        u8 value = 0;
        int status;
-       struct acpi_ec_query_handler *handler, *copy;
+       struct acpi_ec_query_handler *handler;
 
        status = acpi_ec_query_unlocked(ec, &value);
        if (data)
@@ -646,15 +672,12 @@ static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data)
        list_for_each_entry(handler, &ec->list, node) {
                if (value == handler->query_bit) {
                        /* have custom handler for this bit */
-                       copy = kmalloc(sizeof(*handler), GFP_KERNEL);
-                       if (!copy)
-                               return -ENOMEM;
-                       memcpy(copy, handler, sizeof(*copy));
+                       handler = acpi_ec_get_query_handler(handler);
                        pr_debug("##### Query(0x%02x) scheduled #####\n",
                                 handler->query_bit);
-                       return acpi_os_execute((copy->func) ?
+                       return acpi_os_execute((handler->func) ?
                                OSL_NOTIFY_HANDLER : OSL_GPE_HANDLER,
-                               acpi_ec_run, copy);
+                               acpi_ec_run, handler);
                }
        }
        return 0;