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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: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Stephen Hemminger 2017-06-25 12:30:28 -07:00 committed by Greg Kroah-Hartman
parent 05d00bc94a
commit 03bad714a1
1 changed files with 19 additions and 8 deletions
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27
drivers/hv/ring_buffer.c
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@ -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 (hv_get_bytes_to_write(rbi) < pending_sz)
return;
if (rbi->ring_buffer->feature_bits.feat_pending_send_sz) {
u32 pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz);
if (orig_write_sz < pending_sz)
vmbus_setevent(channel);
/*
* 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;
}
vmbus_setevent(channel);
}
EXPORT_SYMBOL_GPL(hv_pkt_iter_close);