From: "Rafael J. Wysocki" rafael.j.wysocki@intel.com
[ Upstream commit 3df663a147fe077a6ee8444ec626738946e65547 ]
There is a race condition in acpi_ec_get_query_handler() theoretically allowing query handlers to go away before refernce counting them.
In order to avoid it, call kref_get() on query handlers under ec->mutex.
Also simplify the code a bit while at it.
Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/acpi/ec.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-)
diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index 57eacdcbf8208..1ec55345252b6 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -1043,29 +1043,21 @@ void acpi_ec_unblock_transactions(void) /* -------------------------------------------------------------------------- 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 struct acpi_ec_query_handler * acpi_ec_get_query_handler_by_value(struct acpi_ec *ec, u8 value) { struct acpi_ec_query_handler *handler; - bool found = false;
mutex_lock(&ec->mutex); list_for_each_entry(handler, &ec->list, node) { if (value == handler->query_bit) { - found = true; - break; + kref_get(&handler->kref); + mutex_unlock(&ec->mutex); + return handler; } } mutex_unlock(&ec->mutex); - return found ? acpi_ec_get_query_handler(handler) : NULL; + return NULL; }
static void acpi_ec_query_handler_release(struct kref *kref)