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Commit 687f32e6 authored by K. Y. Srinivasan's avatar K. Y. Srinivasan Committed by Greg Kroah-Hartman
Browse files

Drivers: hv: vmbus: Move some ring buffer functions to hyperv.h 



In preparation for implementing APIs for in-place consumption of VMBUS
packets, movve some ring buffer functionality into hyperv.h

Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5cc47247

drivers/hv/ring_buffer.c

+0 −55
Original line number Diff line number Diff line
@@ -84,52 +84,6 @@ static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) 
	return false;

}



/*

 * To optimize the flow management on the send-side,

 * when the sender is blocked because of lack of

 * sufficient space in the ring buffer, potential the

 * consumer of the ring buffer can signal the producer.

 * This is controlled by the following parameters:

 *

 * 1. pending_send_sz: This is the size in bytes that the

 *    producer is trying to send.

 * 2. The feature bit feat_pending_send_sz set to indicate if

 *    the consumer of the ring will signal when the ring

 *    state transitions from being full to a state where

 *    there is room for the producer to send the pending packet.

 */



static bool hv_need_to_signal_on_read(struct hv_ring_buffer_info *rbi)

{

	u32 cur_write_sz;

	u32 pending_sz;



	/*

	 * Issue a full memory barrier before making the signaling decision.

	 * Here is the reason for having this barrier:

	 * If the reading of the pend_sz (in this function)

	 * were to be reordered and read before we commit the new read

	 * index (in the calling function)  we could

	 * have a problem. If the host were to set the pending_sz after we

	 * have sampled pending_sz and go to sleep before we commit the

	 * read index, we could miss sending the interrupt. Issue a full

	 * memory barrier to address this.

	 */

	virt_mb();



	pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz);

	/* If the other end is not blocked on write don't bother. */

	if (pending_sz == 0)

		return false;



	cur_write_sz = hv_get_bytes_to_write(rbi);



	if (cur_write_sz >= pending_sz)

		return true;



	return false;

}



/* Get the next write location for the specified ring buffer. */

static inline u32

hv_get_next_write_location(struct hv_ring_buffer_info *ring_info)
@@ -180,15 +134,6 @@ hv_set_next_read_location(struct hv_ring_buffer_info *ring_info, 
	ring_info->ring_buffer->read_index = next_read_location;

}





/* Get the start of the ring buffer. */

static inline void *

hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info)

{

	return (void *)ring_info->ring_buffer->buffer;

}





/* Get the size of the ring buffer. */

static inline u32

hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info)

include/linux/hyperv.h

+54 −0
Original line number Diff line number Diff line
@@ -1366,4 +1366,58 @@ extern __u32 vmbus_proto_version; 
int vmbus_send_tl_connect_request(const uuid_le *shv_guest_servie_id,

				  const uuid_le *shv_host_servie_id);

void vmbus_set_event(struct vmbus_channel *channel);



/* Get the start of the ring buffer. */

static inline void *

hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info)

{

	return (void *)ring_info->ring_buffer->buffer;

}



/*

 * To optimize the flow management on the send-side,

 * when the sender is blocked because of lack of

 * sufficient space in the ring buffer, potential the

 * consumer of the ring buffer can signal the producer.

 * This is controlled by the following parameters:

 *

 * 1. pending_send_sz: This is the size in bytes that the

 *    producer is trying to send.

 * 2. The feature bit feat_pending_send_sz set to indicate if

 *    the consumer of the ring will signal when the ring

 *    state transitions from being full to a state where

 *    there is room for the producer to send the pending packet.

 */



static inline  bool hv_need_to_signal_on_read(struct hv_ring_buffer_info *rbi)

{

	u32 cur_write_sz;

	u32 pending_sz;



	/*

	 * Issue a full memory barrier before making the signaling decision.

	 * Here is the reason for having this barrier:

	 * If the reading of the pend_sz (in this function)

	 * were to be reordered and read before we commit the new read

	 * index (in the calling function)  we could

	 * have a problem. If the host were to set the pending_sz after we

	 * have sampled pending_sz and go to sleep before we commit the

	 * read index, we could miss sending the interrupt. Issue a full

	 * memory barrier to address this.

	 */

	virt_mb();



	pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz);

	/* If the other end is not blocked on write don't bother. */

	if (pending_sz == 0)

		return false;



	cur_write_sz = hv_get_bytes_to_write(rbi);



	if (cur_write_sz >= pending_sz)

		return true;



	return false;

}



#endif /* _HYPERV_H */