[PATCH v2 05/10] ACPI/EC: Add reference counting for query handlers.

Lv Zheng
2014-07-15T03:17:24Z

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>
---
drivers/acpi/ec.c | 46 ++++++++++++++++++++++++++++++++++++----------
1 file changed, 36 insertions(+), 10 deletions(-)

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index d4c07b9..cf83872 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 {
@@ -119,6 +120,10 @@ struct transaction {
u8 flags;
};

+static struct acpi_ec_query_handler *
+acpi_ec_get_query_handler(struct acpi_ec_query_handler *handler);
+static void acpi_ec_put_query_handler(struct acpi_ec_query_handler *handler);
+
struct acpi_ec *boot_ec, *first_ec;
EXPORT_SYMBOL(first_ec);

@@ -590,6 +595,26 @@ 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)
@@ -604,6 +629,7 @@ 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;
@@ -614,14 +640,17 @@ 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);
@@ -637,14 +666,14 @@ static void acpi_ec_run(void *cxt)
else if (handler->handle)
acpi_evaluate_object(handler->handle, NULL, NULL, NULL);
pr_debug("stop query execution\n");
- 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)
@@ -655,15 +684,12 @@ 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("push query execution (0x%2x) on queue\n",
value);
- 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;
--
1.7.10