diff --git a/drivers/gpu/nvgpu/include/nvgpu/posix/queue.h b/drivers/gpu/nvgpu/include/nvgpu/posix/queue.h
index 2df9a0c36..17d1c6f6a 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/posix/queue.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/posix/queue.h
@@ -33,10 +33,10 @@ struct nvgpu_posix_fault_inj;
  * varying length. An user has to request for the allocation of required size
  * of memory to hold the messages before using any other public API of this
  * unit. Requested size for allocation should be greater than zero and less
- * than or equal to INT_MAX. The alloc function ensures that the allocated size
+ * than or equal to INT32_MAX. The alloc function ensures that the allocated size
  * is always a power of two, irrespective of the requested size. It does that
  * by rounding up the requested size to nearest power of two if required. This
- * structure holds in and out indexes used to push and pop the messages
+ * structure holds in and out indexes used to enqueue and dequeue the messages
  * respectively. A mask value to indicate the size of the queue is also held.
  */
 struct nvgpu_queue {
@@ -58,18 +58,6 @@ struct nvgpu_queue {
 	unsigned char *data;
 };
 
-/**
- * @brief Calculate the unused message queue length.
- *
- * The size of all the messages currently enqueued is subtracted from the total
- * size of the queue to get the unused queue length.
- *
- * @param queue [in]	Queue structure to use.
- *
- * @return Return unused queue length.
- */
-unsigned int nvgpu_queue_unused(struct nvgpu_queue *queue);
-
 /**
  * @brief Calculate the length of the message queue in use.
  *
@@ -113,6 +101,7 @@ int nvgpu_queue_alloc(struct nvgpu_queue *queue, unsigned int size);
  */
 void nvgpu_queue_free(struct nvgpu_queue *queue);
 
+#ifdef CONFIG_NVGPU_NON_FUSA
 /**
  * @brief Enqueue message into message queue.
  *
@@ -124,7 +113,7 @@ void nvgpu_queue_free(struct nvgpu_queue *queue);
  * @param buf [in]	Pointer to source message buffer.
  * @param len [in]	Size of the message to be enqueued.
  *
- * @return Returns \a len on success, otherwise returns error number to indicate
+ * @return Returns 0 on success, otherwise returns error number to indicate
  * the error.
  *
  * @retval -ENOMEM if the message queue doesn't have enough free space to
@@ -132,6 +121,7 @@ void nvgpu_queue_free(struct nvgpu_queue *queue);
  */
 int nvgpu_queue_in(struct nvgpu_queue *queue, const void *buf,
 		unsigned int len);
+#endif
 
 /**
  * @brief Enqueue message into message queue after acquiring the mutex lock.
@@ -147,7 +137,7 @@ int nvgpu_queue_in(struct nvgpu_queue *queue, const void *buf,
  * @param len [in]	Size of the message to be enqueued.
  * @param lock [in]	Mutex lock for concurrency management.
  *
- * @return Returns \a len on success, otherwise returns error number to indicate
+ * @return Returns 0 on success, otherwise returns error number to indicate
  * the error.
  *
  * @retval -ENOMEM if the message queue doesn't have enough free space to
@@ -156,6 +146,7 @@ int nvgpu_queue_in(struct nvgpu_queue *queue, const void *buf,
 int nvgpu_queue_in_locked(struct nvgpu_queue *queue, const void *buf,
 		unsigned int len, struct nvgpu_mutex *lock);
 
+#ifdef CONFIG_NVGPU_NON_FUSA
 /**
  * @brief Dequeue message from message queue.
  *
@@ -166,7 +157,7 @@ int nvgpu_queue_in_locked(struct nvgpu_queue *queue, const void *buf,
  * @param buf [in]	Pointer to destination message buffer.
  * @param len [in]	Size of the message to be dequeued.
  *
- * @return Returns \a len on success, otherwise returns error number to indicate
+ * @return Returns 0 on success, otherwise returns error number to indicate
  * the error.
  *
  * @retval -ENOMEM if the length of the messages held by the message queue is
@@ -174,6 +165,7 @@ int nvgpu_queue_in_locked(struct nvgpu_queue *queue, const void *buf,
  */
 int nvgpu_queue_out(struct nvgpu_queue *queue, void *buf,
 		unsigned int len);
+#endif
 
 /**
  * @brief Dequeue message from message queue after acquiring the mutex lock.
@@ -188,7 +180,7 @@ int nvgpu_queue_out(struct nvgpu_queue *queue, void *buf,
  * @param len [in]	Size of the message to be dequeued.
  * @param lock [in]	Mutex lock for concurrency management.
  *
- * @return Returns \a len on success, otherwise returns error number to indicate
+ * @return Returns 0 on success, otherwise returns error number to indicate
  * the error.
  *
  * @retval -ENOMEM if the length of the messages held by the message queue is
diff --git a/drivers/gpu/nvgpu/os/posix/queue.c b/drivers/gpu/nvgpu/os/posix/queue.c
index c42e9f200..4c5c3813d 100644
--- a/drivers/gpu/nvgpu/os/posix/queue.c
+++ b/drivers/gpu/nvgpu/os/posix/queue.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2019, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2018-2021, NVIDIA CORPORATION.  All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -42,10 +42,18 @@ struct nvgpu_posix_fault_inj *nvgpu_queue_out_get_fault_injection(void)
 
 unsigned int nvgpu_queue_available(struct nvgpu_queue *queue)
 {
-	return nvgpu_safe_sub_u32(queue->in, queue->out);
+	u32 ret;
+
+	if (queue->in >= queue->out) {
+		ret = queue->in - queue->out;
+	} else {
+		ret = (UINT32_MAX - queue->out) + (queue->in + 1U);
+	}
+
+	return ret;
 }
 
-unsigned int nvgpu_queue_unused(struct nvgpu_queue *queue)
+static unsigned int nvgpu_queue_unused(struct nvgpu_queue *queue)
 {
 	return nvgpu_safe_sub_u32(nvgpu_safe_add_u32(queue->mask, 1U),
 			nvgpu_queue_available(queue));
@@ -114,7 +122,9 @@ static int posix_queue_in_common(struct nvgpu_queue *queue, const void *src,
 	if (lock != NULL) {
 		nvgpu_mutex_acquire(lock);
 	}
+
 	l = nvgpu_queue_unused(queue);
+
 	if (len > l) {
 		if (lock != NULL) {
 			nvgpu_mutex_release(lock);
@@ -128,19 +138,26 @@ static int posix_queue_in_common(struct nvgpu_queue *queue, const void *src,
 	 */
 	nvgpu_smp_wmb();
 
-	queue->in = nvgpu_safe_add_u32(queue->in, len);
+	if ((UINT_MAX - queue->in) < len) {
+		queue->in = (len - (UINT_MAX - queue->in)) - 1U;
+	} else {
+		queue->in = queue->in + len;
+	}
+
 	if (lock != NULL) {
 		nvgpu_mutex_release(lock);
 	}
 
-	return (int)len;
+	return 0;
 }
 
+#ifdef CONFIG_NVGPU_NON_FUSA
 int nvgpu_queue_in(struct nvgpu_queue *queue, const void *buf,
 		unsigned int len)
 {
 	return posix_queue_in_common(queue, buf, len, NULL);
 }
+#endif
 
 int nvgpu_queue_in_locked(struct nvgpu_queue *queue, const void *buf,
 		unsigned int len, struct nvgpu_mutex *lock)
@@ -173,7 +190,8 @@ static int nvgpu_queue_out_common(struct nvgpu_queue *queue, void *buf,
 	if (lock != NULL) {
 		nvgpu_mutex_acquire(lock);
 	}
-	l = queue->in - queue->out;
+
+	l = nvgpu_queue_available(queue);
 	if (l < len) {
 		if (lock != NULL) {
 			nvgpu_mutex_release(lock);
@@ -186,19 +204,26 @@ static int nvgpu_queue_out_common(struct nvgpu_queue *queue, void *buf,
 	 */
 	nvgpu_smp_wmb();
 
-	queue->out = nvgpu_safe_add_u32(queue->out, len);
+	if ((UINT_MAX - queue->out) < len) {
+		queue->out = (len - (UINT_MAX - queue->out)) - 1U;
+	} else {
+		queue->out = queue->out + len;
+	}
+
 	if (lock != NULL) {
 		nvgpu_mutex_release(lock);
 	}
 
-	return (int)len;
+	return 0;
 }
 
+#ifdef CONFIG_NVGPU_NON_FUSA
 int nvgpu_queue_out(struct nvgpu_queue *queue, void *buf,
 		unsigned int len)
 {
 	return nvgpu_queue_out_common(queue, buf, len, NULL);
 }
+#endif
 
 int nvgpu_queue_out_locked(struct nvgpu_queue *queue, void *buf,
 		unsigned int len, struct nvgpu_mutex *lock)
diff --git a/libs/dgpu/libnvgpu-drv-dgpu_safe.export b/libs/dgpu/libnvgpu-drv-dgpu_safe.export
index 0912d3a87..c06947b5b 100644
--- a/libs/dgpu/libnvgpu-drv-dgpu_safe.export
+++ b/libs/dgpu/libnvgpu-drv-dgpu_safe.export
@@ -637,9 +637,7 @@ nvgpu_posix_register_io
 nvgpu_pte_words
 nvgpu_queue_alloc
 nvgpu_queue_free
-nvgpu_queue_in
 nvgpu_queue_in_locked
-nvgpu_queue_out
 nvgpu_queue_out_locked
 nvgpu_queue_out_get_fault_injection
 nvgpu_queue_available
diff --git a/libs/igpu/libnvgpu-drv-igpu_safe.export b/libs/igpu/libnvgpu-drv-igpu_safe.export
index 418f4e79c..57d100d03 100644
--- a/libs/igpu/libnvgpu-drv-igpu_safe.export
+++ b/libs/igpu/libnvgpu-drv-igpu_safe.export
@@ -654,9 +654,7 @@ nvgpu_posix_register_io
 nvgpu_pte_words
 nvgpu_queue_alloc
 nvgpu_queue_free
-nvgpu_queue_in
 nvgpu_queue_in_locked
-nvgpu_queue_out
 nvgpu_queue_out_locked
 nvgpu_queue_out_get_fault_injection
 nvgpu_queue_available