target/linux/layerscape/patches-5.4/701-net-0191-dpaa2-eth-Avoid-unbounded-while-loops.patch

   1 From 3420c5bf9d08df074b67c7feda8a37d951d0b232 Mon Sep 17 00:00:00 2001
   2 From: Ioana Radulescu <ruxandra.radulescu@nxp.com>
   3 Date: Wed, 18 Sep 2019 13:31:07 +0300
   4 Subject: [PATCH] dpaa2-eth: Avoid unbounded while loops
   5
   6 Throughout the driver there are several places where we wait
   7 indefinitely for DPIO portal commands to be executed, while
   8 the portal returns a busy response code.
   9
  10 Even though in theory we are guaranteed the portals become
  11 available eventually, in practice the QBMan hardware module
  12 may become unresponsive in various corner cases.
  13
  14 Make sure we can never get stuck in an infinite while loop
  15 by adding a retry counter for all portal commands.
  16
  17 Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
  18 ---
  19  drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c | 30 ++++++++++++++++++++----
  20  drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h |  8 +++++++
  21  2 files changed, 33 insertions(+), 5 deletions(-)
  22
  23 --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
  24 +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
  25 @@ -221,6 +221,7 @@ static void xdp_release_buf(struct dpaa2
  26                             struct dpaa2_eth_channel *ch,
  27                             dma_addr_t addr)
  28  {
  29 +       int retries = 0;
  30         int err;
  31
  32         ch->xdp.drop_bufs[ch->xdp.drop_cnt++] = addr;
  33 @@ -229,8 +230,11 @@ static void xdp_release_buf(struct dpaa2
  34
  35         while ((err = dpaa2_io_service_release(ch->dpio, priv->bpid,
  36                                                ch->xdp.drop_bufs,
  37 -                                              ch->xdp.drop_cnt)) == -EBUSY)
  38 +                                              ch->xdp.drop_cnt)) == -EBUSY) {
  39 +               if (retries++ >= DPAA2_ETH_SWP_BUSY_RETRIES)
  40 +                       break;
  41                 cpu_relax();
  42 +       }
  43
  44         if (err) {
  45                 free_bufs(priv, ch->xdp.drop_bufs, ch->xdp.drop_cnt);
  46 @@ -458,7 +462,7 @@ static int consume_frames(struct dpaa2_e
  47         struct dpaa2_eth_fq *fq = NULL;
  48         struct dpaa2_dq *dq;
  49         const struct dpaa2_fd *fd;
  50 -       int cleaned = 0;
  51 +       int cleaned = 0, retries = 0;
  52         int is_last;
  53
  54         do {
  55 @@ -469,6 +473,11 @@ static int consume_frames(struct dpaa2_e
  56                          * the store until we get some sort of valid response
  57                          * token (either a valid frame or an "empty dequeue")
  58                          */
  59 +                       if (retries++ >= DPAA2_ETH_SWP_BUSY_RETRIES) {
  60 +                               netdev_err_once(priv->net_dev,
  61 +                                               "Unable to read a valid dequeue response\n");
  62 +                               return 0;
  63 +                       }
  64                         continue;
  65                 }
  66
  67 @@ -477,6 +486,7 @@ static int consume_frames(struct dpaa2_e
  68
  69                 fq->consume(priv, ch, fd, fq);
  70                 cleaned++;
  71 +               retries = 0;
  72         } while (!is_last);
  73
  74         if (!cleaned)
  75 @@ -949,6 +959,7 @@ static int add_bufs(struct dpaa2_eth_pri
  76         u64 buf_array[DPAA2_ETH_BUFS_PER_CMD];
  77         struct page *page;
  78         dma_addr_t addr;
  79 +       int retries = 0;
  80         int i, err;
  81
  82         for (i = 0; i < DPAA2_ETH_BUFS_PER_CMD; i++) {
  83 @@ -980,8 +991,11 @@ static int add_bufs(struct dpaa2_eth_pri
  84  release_bufs:
  85         /* In case the portal is busy, retry until successful */
  86         while ((err = dpaa2_io_service_release(ch->dpio, bpid,
  87 -                                              buf_array, i)) == -EBUSY)
  88 +                                              buf_array, i)) == -EBUSY) {
  89 +               if (retries++ >= DPAA2_ETH_SWP_BUSY_RETRIES)
  90 +                       break;
  91                 cpu_relax();
  92 +       }
  93
  94         /* If release command failed, clean up and bail out;
  95          * not much else we can do about it
  96 @@ -1032,16 +1046,21 @@ static int seed_pool(struct dpaa2_eth_pr
  97  static void drain_bufs(struct dpaa2_eth_priv *priv, int count)
  98  {
  99         u64 buf_array[DPAA2_ETH_BUFS_PER_CMD];
 100 +       int retries = 0;
 101         int ret;
 102
 103         do {
 104                 ret = dpaa2_io_service_acquire(NULL, priv->bpid,
 105                                                buf_array, count);
 106                 if (ret < 0) {
 107 +                       if (ret == -EBUSY &&
 108 +                           retries++ >= DPAA2_ETH_SWP_BUSY_RETRIES)
 109 +                               continue;
 110                         netdev_err(priv->net_dev, "dpaa2_io_service_acquire() failed\n");
 111                         return;
 112                 }
 113                 free_bufs(priv, buf_array, ret);
 114 +               retries = 0;
 115         } while (ret);
 116  }
 117
 118 @@ -1094,7 +1113,7 @@ static int pull_channel(struct dpaa2_eth
 119                                                     ch->store);
 120                 dequeues++;
 121                 cpu_relax();
 122 -       } while (err == -EBUSY);
 123 +       } while (err == -EBUSY && dequeues < DPAA2_ETH_SWP_BUSY_RETRIES);
 124
 125         ch->stats.dequeue_portal_busy += dequeues;
 126         if (unlikely(err))
 127 @@ -1118,6 +1137,7 @@ static int dpaa2_eth_poll(struct napi_st
 128         struct netdev_queue *nq;
 129         int store_cleaned, work_done;
 130         struct list_head rx_list;
 131 +       int retries = 0;
 132         int err;
 133
 134         ch = container_of(napi, struct dpaa2_eth_channel, napi);
 135 @@ -1163,7 +1183,7 @@ static int dpaa2_eth_poll(struct napi_st
 136         do {
 137                 err = dpaa2_io_service_rearm(ch->dpio, &ch->nctx);
 138                 cpu_relax();
 139 -       } while (err == -EBUSY);
 140 +       } while (err == -EBUSY && retries++ < DPAA2_ETH_SWP_BUSY_RETRIES);
 141         WARN_ONCE(err, "CDAN notifications rearm failed on core %d",
 142                   ch->nctx.desired_cpu);
 143
 144 --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
 145 +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
 146 @@ -245,6 +245,14 @@ static inline struct dpaa2_faead *dpaa2_
 147   */
 148  #define DPAA2_ETH_ENQUEUE_RETRIES      10
 149
 150 +/* Number of times to retry DPIO portal operations while waiting
 151 + * for portal to finish executing current command and become
 152 + * available. We want to avoid being stuck in a while loop in case
 153 + * hardware becomes unresponsive, but not give up too easily if
 154 + * the portal really is busy for valid reasons
 155 + */
 156 +#define DPAA2_ETH_SWP_BUSY_RETRIES     1000
 157 +
 158  /* Driver statistics, other than those in struct rtnl_link_stats64.
 159   * These are usually collected per-CPU and aggregated by ethtool.
 160   */