From d4bbd21245e600f32074724152f77a4ae9904047 Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Thu, 21 Apr 2016 13:49:32 +0100 Subject: [PATCH] vchiq_arm: Add completion records under the mutex An issue was observed when flushing openmax components which generate a large number of messages returning buffers to host. We occasionally found a duplicate message from 16 messages prior, resulting in a buffer returned twice. While only one thread adds completions, without the mutex you don't get the protection of the automatic memory barrier you get with synchronisation objects. Signed-off-by: Phil Elwell --- drivers/misc/vc04_services/interface/vchiq_arm/vchiq_arm.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) --- a/drivers/misc/vc04_services/interface/vchiq_arm/vchiq_arm.c +++ b/drivers/misc/vc04_services/interface/vchiq_arm/vchiq_arm.c @@ -210,6 +210,8 @@ add_completion(VCHIQ_INSTANCE_T instance VCHIQ_COMPLETION_DATA_T *completion; DEBUG_INITIALISE(g_state.local) + mutex_lock(&instance->completion_mutex); + while (instance->completion_insert == (instance->completion_remove + MAX_COMPLETIONS)) { /* Out of space - wait for the client */ @@ -217,11 +219,17 @@ add_completion(VCHIQ_INSTANCE_T instance vchiq_log_trace(vchiq_arm_log_level, "add_completion - completion queue full"); DEBUG_COUNT(COMPLETION_QUEUE_FULL_COUNT); + + mutex_unlock(&instance->completion_mutex); if (down_interruptible(&instance->remove_event) != 0) { vchiq_log_info(vchiq_arm_log_level, "service_callback interrupted"); return VCHIQ_RETRY; - } else if (instance->closing) { + } + + mutex_lock(&instance->completion_mutex); + if (instance->closing) { + mutex_unlock(&instance->completion_mutex); vchiq_log_info(vchiq_arm_log_level, "service_callback closing"); return VCHIQ_SUCCESS; @@ -254,8 +262,11 @@ add_completion(VCHIQ_INSTANCE_T instance if (reason == VCHIQ_MESSAGE_AVAILABLE) user_service->message_available_pos = instance->completion_insert; + instance->completion_insert++; + mutex_unlock(&instance->completion_mutex); + up(&instance->insert_event); return VCHIQ_SUCCESS;