From 3420c5bf9d08df074b67c7feda8a37d951d0b232 Mon Sep 17 00:00:00 2001 From: Ioana Radulescu Date: Wed, 18 Sep 2019 13:31:07 +0300 Subject: [PATCH] dpaa2-eth: Avoid unbounded while loops Throughout the driver there are several places where we wait indefinitely for DPIO portal commands to be executed, while the portal returns a busy response code. Even though in theory we are guaranteed the portals become available eventually, in practice the QBMan hardware module may become unresponsive in various corner cases. Make sure we can never get stuck in an infinite while loop by adding a retry counter for all portal commands. Signed-off-by: Ioana Radulescu --- drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c | 30 ++++++++++++++++++++---- drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h | 8 +++++++ 2 files changed, 33 insertions(+), 5 deletions(-) --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c @@ -221,6 +221,7 @@ static void xdp_release_buf(struct dpaa2 struct dpaa2_eth_channel *ch, dma_addr_t addr) { + int retries = 0; int err; ch->xdp.drop_bufs[ch->xdp.drop_cnt++] = addr; @@ -229,8 +230,11 @@ static void xdp_release_buf(struct dpaa2 while ((err = dpaa2_io_service_release(ch->dpio, priv->bpid, ch->xdp.drop_bufs, - ch->xdp.drop_cnt)) == -EBUSY) + ch->xdp.drop_cnt)) == -EBUSY) { + if (retries++ >= DPAA2_ETH_SWP_BUSY_RETRIES) + break; cpu_relax(); + } if (err) { free_bufs(priv, ch->xdp.drop_bufs, ch->xdp.drop_cnt); @@ -458,7 +462,7 @@ static int consume_frames(struct dpaa2_e struct dpaa2_eth_fq *fq = NULL; struct dpaa2_dq *dq; const struct dpaa2_fd *fd; - int cleaned = 0; + int cleaned = 0, retries = 0; int is_last; do { @@ -469,6 +473,11 @@ static int consume_frames(struct dpaa2_e * the store until we get some sort of valid response * token (either a valid frame or an "empty dequeue") */ + if (retries++ >= DPAA2_ETH_SWP_BUSY_RETRIES) { + netdev_err_once(priv->net_dev, + "Unable to read a valid dequeue response\n"); + return 0; + } continue; } @@ -477,6 +486,7 @@ static int consume_frames(struct dpaa2_e fq->consume(priv, ch, fd, fq); cleaned++; + retries = 0; } while (!is_last); if (!cleaned) @@ -949,6 +959,7 @@ static int add_bufs(struct dpaa2_eth_pri u64 buf_array[DPAA2_ETH_BUFS_PER_CMD]; struct page *page; dma_addr_t addr; + int retries = 0; int i, err; for (i = 0; i < DPAA2_ETH_BUFS_PER_CMD; i++) { @@ -980,8 +991,11 @@ static int add_bufs(struct dpaa2_eth_pri release_bufs: /* In case the portal is busy, retry until successful */ while ((err = dpaa2_io_service_release(ch->dpio, bpid, - buf_array, i)) == -EBUSY) + buf_array, i)) == -EBUSY) { + if (retries++ >= DPAA2_ETH_SWP_BUSY_RETRIES) + break; cpu_relax(); + } /* If release command failed, clean up and bail out; * not much else we can do about it @@ -1032,16 +1046,21 @@ static int seed_pool(struct dpaa2_eth_pr static void drain_bufs(struct dpaa2_eth_priv *priv, int count) { u64 buf_array[DPAA2_ETH_BUFS_PER_CMD]; + int retries = 0; int ret; do { ret = dpaa2_io_service_acquire(NULL, priv->bpid, buf_array, count); if (ret < 0) { + if (ret == -EBUSY && + retries++ >= DPAA2_ETH_SWP_BUSY_RETRIES) + continue; netdev_err(priv->net_dev, "dpaa2_io_service_acquire() failed\n"); return; } free_bufs(priv, buf_array, ret); + retries = 0; } while (ret); } @@ -1094,7 +1113,7 @@ static int pull_channel(struct dpaa2_eth ch->store); dequeues++; cpu_relax(); - } while (err == -EBUSY); + } while (err == -EBUSY && dequeues < DPAA2_ETH_SWP_BUSY_RETRIES); ch->stats.dequeue_portal_busy += dequeues; if (unlikely(err)) @@ -1118,6 +1137,7 @@ static int dpaa2_eth_poll(struct napi_st struct netdev_queue *nq; int store_cleaned, work_done; struct list_head rx_list; + int retries = 0; int err; ch = container_of(napi, struct dpaa2_eth_channel, napi); @@ -1163,7 +1183,7 @@ static int dpaa2_eth_poll(struct napi_st do { err = dpaa2_io_service_rearm(ch->dpio, &ch->nctx); cpu_relax(); - } while (err == -EBUSY); + } while (err == -EBUSY && retries++ < DPAA2_ETH_SWP_BUSY_RETRIES); WARN_ONCE(err, "CDAN notifications rearm failed on core %d", ch->nctx.desired_cpu); --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h @@ -245,6 +245,14 @@ static inline struct dpaa2_faead *dpaa2_ */ #define DPAA2_ETH_ENQUEUE_RETRIES 10 +/* Number of times to retry DPIO portal operations while waiting + * for portal to finish executing current command and become + * available. We want to avoid being stuck in a while loop in case + * hardware becomes unresponsive, but not give up too easily if + * the portal really is busy for valid reasons + */ +#define DPAA2_ETH_SWP_BUSY_RETRIES 1000 + /* Driver statistics, other than those in struct rtnl_link_stats64. * These are usually collected per-CPU and aggregated by ethtool. */ #n22'>22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181