Merge tag 'v4.10' into patchwork

Linux 4.10

* tag 'v4.10': (1558 commits)
  Linux 4.10
  Fix missing sanity check in /dev/sg
  scsi: don't BUG_ON() empty DMA transfers
  ipv6: release dst on error in ip6_dst_lookup_tail
  printk: use rcuidle console tracepoint
  ARM: multi_v7_defconfig: enable Qualcomm RPMCC
  irda: Fix lockdep annotations in hashbin_delete().
  vxlan: fix oops in dev_fill_metadata_dst
  dccp: fix freeing skb too early for IPV6_RECVPKTINFO
  dpaa_eth: small leak on error
  packet: Do not call fanout_release from atomic contexts
  reset: fix shared reset triggered_count decrement on error
  ntb: ntb_hw_intel: link_poll isn't clearing the pending status properly
  ntb_transport: Pick an unused queue
  ntb: ntb_perf missing dmaengine_unmap_put
  NTB: ntb_transport: fix debugfs_remove_recursive
  Revert "nohz: Fix collision between tick and other hrtimers"
  vfs: fix uninitialized flags in splice_to_pipe()
  drm/radeon: Use mode h/vdisplay fields to hide out of bounds HW cursor
  ARM: 8658/1: uaccess: fix zeroing of 64-bit get_user()
  ...

1 files changed, 30 insertions, 2 deletions

diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 42fe43fb0c80..183efde54269 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -128,6 +128,7 @@ struct hv_ring_buffer_info {
 	u32 ring_data_startoffset;
 	u32 priv_write_index;
 	u32 priv_read_index;
+	u32 cached_read_index;
 };
 
 /*
@@ -180,6 +181,19 @@ static inline u32 hv_get_bytes_to_write(struct hv_ring_buffer_info *rbi)
 	return write;
 }
 
+static inline u32 hv_get_cached_bytes_to_write(
+	const struct hv_ring_buffer_info *rbi)
+{
+	u32 read_loc, write_loc, dsize, write;
+
+	dsize = rbi->ring_datasize;
+	read_loc = rbi->cached_read_index;
+	write_loc = rbi->ring_buffer->write_index;
+
+	write = write_loc >= read_loc ? dsize - (write_loc - read_loc) :
+		read_loc - write_loc;
+	return write;
+}
 /*
  * VMBUS version is 32 bit entity broken up into
  * two 16 bit quantities: major_number. minor_number.
@@ -1488,7 +1502,7 @@ hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info)
 
 static inline  void hv_signal_on_read(struct vmbus_channel *channel)
 {
-	u32 cur_write_sz;
+	u32 cur_write_sz, cached_write_sz;
 	u32 pending_sz;
 	struct hv_ring_buffer_info *rbi = &channel->inbound;
 
@@ -1512,12 +1526,24 @@ static inline  void hv_signal_on_read(struct vmbus_channel *channel)
 
 	cur_write_sz = hv_get_bytes_to_write(rbi);
 
-	if (cur_write_sz >= pending_sz)
+	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);
 
 	return;
 }
 
+static inline void
+init_cached_read_index(struct vmbus_channel *channel)
+{
+	struct hv_ring_buffer_info *rbi = &channel->inbound;
+
+	rbi->cached_read_index = rbi->ring_buffer->read_index;
+}
+
 /*
  * An API to support in-place processing of incoming VMBUS packets.
  */
@@ -1569,6 +1595,8 @@ static inline void put_pkt_raw(struct vmbus_channel *channel,
  * This call commits the read index and potentially signals the host.
  * Here is the pattern for using the "in-place" consumption APIs:
  *
+ * init_cached_read_index();
+ *
  * while (get_next_pkt_raw() {
  *	process the packet "in-place";
  *	put_pkt_raw();