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>

1 files changed, 33 insertions, 10 deletions

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 3e19123bb183..87b9911c9039 100644
--- 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;