From ef17bd7cc0c8bb14ea532fb66a708b02c5a4297e Mon Sep 17 00:00:00 2001 From: Ioana Radulescu Date: Mon, 7 Oct 2019 14:38:28 +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 Signed-off-by: Ioana Ciornei Signed-off-by: David S. Miller --- .../net/ethernet/freescale/dpaa2/dpaa2-eth.c | 32 +++++++++++++++---- .../net/ethernet/freescale/dpaa2/dpaa2-eth.h | 8 +++++ 2 files changed, 34 insertions(+), 6 deletions(-) diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c index 2c5072fa9aa0..1b959d7ec923 100644 --- 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_eth_priv *priv, 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_eth_priv *priv, 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_eth_channel *ch, 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_eth_channel *ch, * 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 -ETIMEDOUT; + } continue; } @@ -477,6 +486,7 @@ static int consume_frames(struct dpaa2_eth_channel *ch, 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_priv *priv, 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_priv *priv, 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_priv *priv, u16 bpid) 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_channel *ch) 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_struct *napi, int budget) 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); @@ -1136,7 +1156,7 @@ static int dpaa2_eth_poll(struct napi_struct *napi, int budget) refill_pool(priv, ch, priv->bpid); store_cleaned = consume_frames(ch, &fq); - if (!store_cleaned) + if (store_cleaned <= 0) break; if (fq->type == DPAA2_RX_FQ) { rx_cleaned += store_cleaned; @@ -1163,7 +1183,7 @@ static int dpaa2_eth_poll(struct napi_struct *napi, int budget) 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); diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h index 8a0e65b3267f..686b651edcb2 100644 --- 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_get_faead(void *buf_addr, bool swa) */ #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. */