releases/4.13.9/vmbus-eliminate-duplicate-cached-index.patch

   1 From 05d00bc94ac27d220d8a78e365d7fa3a26dcca17 Mon Sep 17 00:00:00 2001
   2 From: Stephen Hemminger <stephen@networkplumber.org>
   3 Date: Sun, 25 Jun 2017 12:30:27 -0700
   4 Subject: vmbus: eliminate duplicate cached index
   5
   6 From: Stephen Hemminger <stephen@networkplumber.org>
   7
   8 commit 05d00bc94ac27d220d8a78e365d7fa3a26dcca17 upstream.
   9
  10 Don't need cached read index anymore now that packet iterator
  11 is used. The iterator has the original read index until the
  12 visible read_index is updated.
  13
  14 Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
  15 Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
  16 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  17
  18 ---
  19  drivers/hv/ring_buffer.c |   17 ++++-------------
  20  include/linux/hyperv.h   |   14 --------------
  21  2 files changed, 4 insertions(+), 27 deletions(-)
  22
  23 --- a/drivers/hv/ring_buffer.c
  24 +++ b/drivers/hv/ring_buffer.c
  25 @@ -358,9 +358,6 @@ struct vmpacket_descriptor *hv_pkt_iter_
  26  {
  27         struct hv_ring_buffer_info *rbi = &channel->inbound;
  28
  29 -       /* set state for later hv_pkt_iter_close */
  30 -       rbi->cached_read_index = rbi->ring_buffer->read_index;
  31 -
  32         if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
  33                 return NULL;
  34
  35 @@ -388,10 +385,7 @@ __hv_pkt_iter_next(struct vmbus_channel
  36                 rbi->priv_read_index -= dsize;
  37
  38         /* more data? */
  39 -       if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
  40 -               return NULL;
  41 -       else
  42 -               return hv_get_ring_buffer(rbi) + rbi->priv_read_index;
  43 +       return hv_pkt_iter_first(channel);
  44  }
  45  EXPORT_SYMBOL_GPL(__hv_pkt_iter_next);
  46
  47 @@ -401,7 +395,7 @@ EXPORT_SYMBOL_GPL(__hv_pkt_iter_next);
  48  void hv_pkt_iter_close(struct vmbus_channel *channel)
  49  {
  50         struct hv_ring_buffer_info *rbi = &channel->inbound;
  51 -       u32 cur_write_sz, cached_write_sz;
  52 +       u32 orig_write_sz = hv_get_bytes_to_write(rbi);
  53         u32 pending_sz;
  54
  55         /*
  56 @@ -430,13 +424,10 @@ void hv_pkt_iter_close(struct vmbus_chan
  57         if (pending_sz == 0)
  58                 return;
  59
  60 -       cur_write_sz = hv_get_bytes_to_write(rbi);
  61 -
  62 -       if (cur_write_sz < pending_sz)
  63 +       if (hv_get_bytes_to_write(rbi) < pending_sz)
  64                 return;
  65
  66 -       cached_write_sz = hv_get_cached_bytes_to_write(rbi);
  67 -       if (cached_write_sz < pending_sz)
  68 +       if (orig_write_sz < pending_sz)
  69                 vmbus_setevent(channel);
  70  }
  71  EXPORT_SYMBOL_GPL(hv_pkt_iter_close);
  72 --- a/include/linux/hyperv.h
  73 +++ b/include/linux/hyperv.h
  74 @@ -127,7 +127,6 @@ struct hv_ring_buffer_info {
  75         u32 ring_data_startoffset;
  76         u32 priv_write_index;
  77         u32 priv_read_index;
  78 -       u32 cached_read_index;
  79  };
  80
  81  /*
  82 @@ -180,19 +179,6 @@ static inline u32 hv_get_bytes_to_write(
  83         return write;
  84  }
  85
  86 -static inline u32 hv_get_cached_bytes_to_write(
  87 -       const struct hv_ring_buffer_info *rbi)
  88 -{
  89 -       u32 read_loc, write_loc, dsize, write;
  90 -
  91 -       dsize = rbi->ring_datasize;
  92 -       read_loc = rbi->cached_read_index;
  93 -       write_loc = rbi->ring_buffer->write_index;
  94 -
  95 -       write = write_loc >= read_loc ? dsize - (write_loc - read_loc) :
  96 -               read_loc - write_loc;
  97 -       return write;
  98 -}
  99  /*
 100   * VMBUS version is 32 bit entity broken up into
 101   * two 16 bit quantities: major_number. minor_number.