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Commit 8dd45f2a authored by Stephen Hemminger's avatar Stephen Hemminger Committed by Greg Kroah-Hartman
Browse files

vmbus: refactor hv_signal_on_read 



The function hv_signal_on_read was defined in hyperv.h and
only used in one place in ring_buffer code. Clearer to just
move it inline there.

Signed-off-by: default avatarStephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 95c40f41

drivers/hv/ring_buffer.c

+30 −2
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <linux/uio.h>

#include <linux/vmalloc.h>

#include <linux/slab.h>

#include <linux/prefetch.h>



#include "hyperv_vmbus.h"
@@ -357,7 +358,7 @@ struct vmpacket_descriptor *hv_pkt_iter_first(struct vmbus_channel *channel) 
{

	struct hv_ring_buffer_info *rbi = &channel->inbound;



	/* set state for later hv_signal_on_read() */

	/* set state for later hv_pkt_iter_close */

	rbi->cached_read_index = rbi->ring_buffer->read_index;



	if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
@@ -400,6 +401,8 @@ EXPORT_SYMBOL_GPL(__hv_pkt_iter_next); 
void hv_pkt_iter_close(struct vmbus_channel *channel)

{

	struct hv_ring_buffer_info *rbi = &channel->inbound;

	u32 cur_write_sz, cached_write_sz;

	u32 pending_sz;



	/*

	 * Make sure all reads are done before we update the read index since
@@ -409,6 +412,31 @@ void hv_pkt_iter_close(struct vmbus_channel *channel) 
	virt_rmb();

	rbi->ring_buffer->read_index = rbi->priv_read_index;



	hv_signal_on_read(channel);

	/*

	 * 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;



	cur_write_sz = hv_get_bytes_to_write(rbi);



	if (cur_write_sz < pending_sz)

		return;



	cached_write_sz = hv_get_cached_bytes_to_write(rbi);

	if (cached_write_sz < pending_sz)

		vmbus_setevent(channel);

}

EXPORT_SYMBOL_GPL(hv_pkt_iter_close);

include/linux/hyperv.h

+0 −49
Original line number Diff line number Diff line
@@ -1471,55 +1471,6 @@ hv_get_ring_buffer(const struct hv_ring_buffer_info *ring_info) 
	return 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  void hv_signal_on_read(struct vmbus_channel *channel)

{

	u32 cur_write_sz, cached_write_sz;

	u32 pending_sz;

	struct hv_ring_buffer_info *rbi = &channel->inbound;



	/*

	 * 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;



	cur_write_sz = hv_get_bytes_to_write(rbi);



	if (cur_write_sz < pending_sz)

		return;



	cached_write_sz = hv_get_cached_bytes_to_write(rbi);

	if (cached_write_sz < pending_sz)

		vmbus_setevent(channel);

}



/*

 * Mask off host interrupt callback notifications

 */