Commit 03bad714 authored by Stephen Hemminger's avatar Stephen Hemminger Committed by Greg Kroah-Hartman
Browse files

vmbus: more host signalling avoidance 



Don't signal host if it has disabled interrupts for that
ring buffer. Check the feature bit to see if host supports
pending send size flag.

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 05d00bc9

drivers/hv/ring_buffer.c

+19 −8
Original line number Diff line number Diff line
@@ -396,7 +396,6 @@ void hv_pkt_iter_close(struct vmbus_channel *channel) 
{

	struct hv_ring_buffer_info *rbi = &channel->inbound;

	u32 orig_write_sz = hv_get_bytes_to_write(rbi);

	u32 pending_sz;



	/*

	 * Make sure all reads are done before we update the read index since
@@ -419,15 +418,27 @@ void hv_pkt_iter_close(struct vmbus_channel *channel) 
	 */

	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)

	/* If host has disabled notifications then skip */

	if (rbi->ring_buffer->interrupt_mask)

		return;



	if (rbi->ring_buffer->feature_bits.feat_pending_send_sz) {

		u32 pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz);



		/*

		 * If there was space before we began iteration,

		 * then host was not blocked. Also handles case where

		 * pending_sz is zero then host has nothing pending

		 * and does not need to be signaled.

		 */

		if (orig_write_sz > pending_sz)

			return;



		/* If pending write will not fit, don't give false hope. */

		if (hv_get_bytes_to_write(rbi) < pending_sz)

			return;

	}



	if (orig_write_sz < pending_sz)

	vmbus_setevent(channel);

}

EXPORT_SYMBOL_GPL(hv_pkt_iter_close);