From mboxrd@z Thu Jan 1 00:00:00 1970 From: Edward Cree Subject: [PATCH net 2/2] sfc: limit ARFS workitems in flight per channel Date: Thu, 12 Apr 2018 15:02:50 +0100 Message-ID: References: <1713aaa9-2803-0d3b-127a-5240876da7b1@solarflare.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: netdev To: , David Miller Return-path: Received: from dispatch1-us1.ppe-hosted.com ([67.231.154.164]:40362 "EHLO dispatch1-us1.ppe-hosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752406AbeDLOC6 (ORCPT ); Thu, 12 Apr 2018 10:02:58 -0400 In-Reply-To: <1713aaa9-2803-0d3b-127a-5240876da7b1@solarflare.com> Content-Language: en-GB Sender: netdev-owner@vger.kernel.org List-ID: A misconfigured system (e.g. with all interrupts affinitised to all CPUs) may produce a storm of ARFS steering events. With the existing sfc ARFS implementation, that could create a backlog of workitems that grinds the system to a halt. To prevent this, limit the number of workitems that may be in flight for a given SFC device to 8 (EFX_RPS_MAX_IN_FLIGHT), and return EBUSY from our ndo_rx_flow_steer method if the limit is reached. Given this limit, also store the workitems in an array of slots within the struct efx_nic, rather than dynamically allocating for each request. Signed-off-by: Edward Cree --- drivers/net/ethernet/sfc/net_driver.h | 25 +++++++++++++++ drivers/net/ethernet/sfc/rx.c | 58 ++++++++++++++++++----------------- 2 files changed, 55 insertions(+), 28 deletions(-) diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h index 5e379a83c729..eea3808b3f25 100644 --- a/drivers/net/ethernet/sfc/net_driver.h +++ b/drivers/net/ethernet/sfc/net_driver.h @@ -733,6 +733,27 @@ struct efx_rss_context { u32 rx_indir_table[128]; }; +#ifdef CONFIG_RFS_ACCEL +/** + * struct efx_async_filter_insertion - Request to asynchronously insert a filter + * @net_dev: Reference to the netdevice + * @spec: The filter to insert + * @work: Workitem for this request + * @rxq_index: Identifies the channel for which this request was made + * @flow_id: Identifies the kernel-side flow for which this request was made + */ +struct efx_async_filter_insertion { + struct net_device *net_dev; + struct efx_filter_spec spec; + struct work_struct work; + u16 rxq_index; + u32 flow_id; +}; + +/* Maximum number of ARFS workitems that may be in flight on an efx_nic */ +#define EFX_RPS_MAX_IN_FLIGHT 8 +#endif /* CONFIG_RFS_ACCEL */ + /** * struct efx_nic - an Efx NIC * @name: Device name (net device name or bus id before net device registered) @@ -850,6 +871,8 @@ struct efx_rss_context { * @rps_expire_channel: Next channel to check for expiry * @rps_expire_index: Next index to check for expiry in * @rps_expire_channel's @rps_flow_id + * @rps_slot_map: bitmap of in-flight entries in @rps_slot + * @rps_slot: array of ARFS insertion requests for efx_filter_rfs_work() * @active_queues: Count of RX and TX queues that haven't been flushed and drained. * @rxq_flush_pending: Count of number of receive queues that need to be flushed. * Decremented when the efx_flush_rx_queue() is called. @@ -1004,6 +1027,8 @@ struct efx_nic { struct mutex rps_mutex; unsigned int rps_expire_channel; unsigned int rps_expire_index; + unsigned long rps_slot_map; + struct efx_async_filter_insertion rps_slot[EFX_RPS_MAX_IN_FLIGHT]; #endif atomic_t active_queues; diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c index 13b0eb71dbf3..9c593c661cbf 100644 --- a/drivers/net/ethernet/sfc/rx.c +++ b/drivers/net/ethernet/sfc/rx.c @@ -827,28 +827,13 @@ MODULE_PARM_DESC(rx_refill_threshold, #ifdef CONFIG_RFS_ACCEL -/** - * struct efx_async_filter_insertion - Request to asynchronously insert a filter - * @net_dev: Reference to the netdevice - * @spec: The filter to insert - * @work: Workitem for this request - * @rxq_index: Identifies the channel for which this request was made - * @flow_id: Identifies the kernel-side flow for which this request was made - */ -struct efx_async_filter_insertion { - struct net_device *net_dev; - struct efx_filter_spec spec; - struct work_struct work; - u16 rxq_index; - u32 flow_id; -}; - static void efx_filter_rfs_work(struct work_struct *data) { struct efx_async_filter_insertion *req = container_of(data, struct efx_async_filter_insertion, work); struct efx_nic *efx = netdev_priv(req->net_dev); struct efx_channel *channel = efx_get_channel(efx, req->rxq_index); + int slot_idx = req - efx->rps_slot; int rc; rc = efx->type->filter_insert(efx, &req->spec, true); @@ -878,8 +863,8 @@ static void efx_filter_rfs_work(struct work_struct *data) } /* Release references */ + clear_bit(slot_idx, &efx->rps_slot_map); dev_put(req->net_dev); - kfree(req); } int efx_filter_rfs(struct net_device *net_dev, const struct sk_buff *skb, @@ -888,22 +873,36 @@ int efx_filter_rfs(struct net_device *net_dev, const struct sk_buff *skb, struct efx_nic *efx = netdev_priv(net_dev); struct efx_async_filter_insertion *req; struct flow_keys fk; + int slot_idx; + int rc; - if (flow_id == RPS_FLOW_ID_INVALID) - return -EINVAL; + /* find a free slot */ + for (slot_idx = 0; slot_idx < EFX_RPS_MAX_IN_FLIGHT; slot_idx++) + if (!test_and_set_bit(slot_idx, &efx->rps_slot_map)) + break; + if (slot_idx >= EFX_RPS_MAX_IN_FLIGHT) + return -EBUSY; - if (!skb_flow_dissect_flow_keys(skb, &fk, 0)) - return -EPROTONOSUPPORT; + if (flow_id == RPS_FLOW_ID_INVALID) { + rc = -EINVAL; + goto out_clear; + } - if (fk.basic.n_proto != htons(ETH_P_IP) && fk.basic.n_proto != htons(ETH_P_IPV6)) - return -EPROTONOSUPPORT; - if (fk.control.flags & FLOW_DIS_IS_FRAGMENT) - return -EPROTONOSUPPORT; + if (!skb_flow_dissect_flow_keys(skb, &fk, 0)) { + rc = -EPROTONOSUPPORT; + goto out_clear; + } - req = kmalloc(sizeof(*req), GFP_ATOMIC); - if (!req) - return -ENOMEM; + if (fk.basic.n_proto != htons(ETH_P_IP) && fk.basic.n_proto != htons(ETH_P_IPV6)) { + rc = -EPROTONOSUPPORT; + goto out_clear; + } + if (fk.control.flags & FLOW_DIS_IS_FRAGMENT) { + rc = -EPROTONOSUPPORT; + goto out_clear; + } + req = efx->rps_slot + slot_idx; efx_filter_init_rx(&req->spec, EFX_FILTER_PRI_HINT, efx->rx_scatter ? EFX_FILTER_FLAG_RX_SCATTER : 0, rxq_index); @@ -933,6 +932,9 @@ int efx_filter_rfs(struct net_device *net_dev, const struct sk_buff *skb, req->flow_id = flow_id; schedule_work(&req->work); return 0; +out_clear: + clear_bit(slot_idx, &efx->rps_slot_map); + return rc; } bool __efx_filter_rfs_expire(struct efx_nic *efx, unsigned int quota)