target/linux/ipq806x/patches-3.18/150-dmaengine-Rework-dma_chan_get.patch

   1 From d2f4f99db3e9ec8b063cf2e45704e2bb95428317 Mon Sep 17 00:00:00 2001
   2 From: Maxime Ripard <maxime.ripard@free-electrons.com>
   3 Date: Mon, 17 Nov 2014 14:41:58 +0100
   4 Subject: [PATCH] dmaengine: Rework dma_chan_get
   5
   6 dma_chan_get uses a rather interesting error handling and code path.
   7
   8 Change it to something more usual in the kernel.
   9
  10 Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
  11 Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
  12 Signed-off-by: Vinod Koul <vinod.koul@intel.com>
  13 ---
  14  drivers/dma/dmaengine.c | 36 +++++++++++++++++++-----------------
  15  1 file changed, 19 insertions(+), 17 deletions(-)
  16
  17 --- a/drivers/dma/dmaengine.c
  18 +++ b/drivers/dma/dmaengine.c
  19 @@ -222,31 +222,33 @@ static void balance_ref_count(struct dma
  20   */
  21  static int dma_chan_get(struct dma_chan *chan)
  22  {
  23 -       int err = -ENODEV;
  24         struct module *owner = dma_chan_to_owner(chan);
  25 +       int ret;
  26
  27 +       /* The channel is already in use, update client count */
  28         if (chan->client_count) {
  29                 __module_get(owner);
  30 -               err = 0;
  31 -       } else if (try_module_get(owner))
  32 -               err = 0;
  33 +               goto out;
  34 +       }
  35
  36 -       if (err == 0)
  37 -               chan->client_count++;
  38 +       if (!try_module_get(owner))
  39 +               return -ENODEV;
  40
  41         /* allocate upon first client reference */
  42 -       if (chan->client_count == 1 && err == 0) {
  43 -               int desc_cnt = chan->device->device_alloc_chan_resources(chan);
  44 -
  45 -               if (desc_cnt < 0) {
  46 -                       err = desc_cnt;
  47 -                       chan->client_count = 0;
  48 -                       module_put(owner);
  49 -               } else if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
  50 -                       balance_ref_count(chan);
  51 -       }
  52 -
  53 -       return err;
  54 +       ret = chan->device->device_alloc_chan_resources(chan);
  55 +       if (ret < 0)
  56 +               goto err_out;
  57 +
  58 +       if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
  59 +               balance_ref_count(chan);
  60 +
  61 +out:
  62 +       chan->client_count++;
  63 +       return 0;
  64 +
  65 +err_out:
  66 +       module_put(owner);
  67 +       return ret;
  68  }
  69
  70  /**