/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_NET_QUEUES_H #define _LINUX_NET_QUEUES_H #include <linux/netdevice.h> /* See the netdev.yaml spec for definition of each statistic */ struct netdev_queue_stats_rx { … }; struct netdev_queue_stats_tx { … }; /** * struct netdev_stat_ops - netdev ops for fine grained stats * @get_queue_stats_rx: get stats for a given Rx queue * @get_queue_stats_tx: get stats for a given Tx queue * @get_base_stats: get base stats (not belonging to any live instance) * * Query stats for a given object. The values of the statistics are undefined * on entry (specifically they are *not* zero-initialized). Drivers should * assign values only to the statistics they collect. Statistics which are not * collected must be left undefined. * * Queue objects are not necessarily persistent, and only currently active * queues are queried by the per-queue callbacks. This means that per-queue * statistics will not generally add up to the total number of events for * the device. The @get_base_stats callback allows filling in the delta * between events for currently live queues and overall device history. * @get_base_stats can also be used to report any miscellaneous packets * transferred outside of the main set of queues used by the networking stack. * When the statistics for the entire device are queried, first @get_base_stats * is issued to collect the delta, and then a series of per-queue callbacks. * Only statistics which are set in @get_base_stats will be reported * at the device level, meaning that unlike in queue callbacks, setting * a statistic to zero in @get_base_stats is a legitimate thing to do. * This is because @get_base_stats has a second function of designating which * statistics are in fact correct for the entire device (e.g. when history * for some of the events is not maintained, and reliable "total" cannot * be provided). * * Device drivers can assume that when collecting total device stats, * the @get_base_stats and subsequent per-queue calls are performed * "atomically" (without releasing the rtnl_lock). * * Device drivers are encouraged to reset the per-queue statistics when * number of queues change. This is because the primary use case for * per-queue statistics is currently to detect traffic imbalance. */ struct netdev_stat_ops { … }; /** * struct netdev_queue_mgmt_ops - netdev ops for queue management * * @ndo_queue_mem_size: Size of the struct that describes a queue's memory. * * @ndo_queue_mem_alloc: Allocate memory for an RX queue at the specified index. * The new memory is written at the specified address. * * @ndo_queue_mem_free: Free memory from an RX queue. * * @ndo_queue_start: Start an RX queue with the specified memory and at the * specified index. * * @ndo_queue_stop: Stop the RX queue at the specified index. The stopped * queue's memory is written at the specified address. */ struct netdev_queue_mgmt_ops { … }; /** * DOC: Lockless queue stopping / waking helpers. * * The netif_txq_maybe_stop() and __netif_txq_completed_wake() * macros are designed to safely implement stopping * and waking netdev queues without full lock protection. * * We assume that there can be no concurrent stop attempts and no concurrent * wake attempts. The try-stop should happen from the xmit handler, * while wake up should be triggered from NAPI poll context. * The two may run concurrently (single producer, single consumer). * * The try-stop side is expected to run from the xmit handler and therefore * it does not reschedule Tx (netif_tx_start_queue() instead of * netif_tx_wake_queue()). Uses of the ``stop`` macros outside of the xmit * handler may lead to xmit queue being enabled but not run. * The waking side does not have similar context restrictions. * * The macros guarantee that rings will not remain stopped if there's * space available, but they do *not* prevent false wake ups when * the ring is full! Drivers should check for ring full at the start * for the xmit handler. * * All descriptor ring indexes (and other relevant shared state) must * be updated before invoking the macros. */ #define netif_txq_try_stop(txq, get_desc, start_thrs) … \ /** * netif_txq_maybe_stop() - locklessly stop a Tx queue, if needed * @txq: struct netdev_queue to stop/start * @get_desc: get current number of free descriptors (see requirements below!) * @stop_thrs: minimal number of available descriptors for queue to be left * enabled * @start_thrs: minimal number of descriptors to re-enable the queue, can be * equal to @stop_thrs or higher to avoid frequent waking * * All arguments may be evaluated multiple times, beware of side effects. * @get_desc must be a formula or a function call, it must always * return up-to-date information when evaluated! * Expected to be used from ndo_start_xmit, see the comment on top of the file. * * Returns: * 0 if the queue was stopped * 1 if the queue was left enabled * -1 if the queue was re-enabled (raced with waking) */ #define netif_txq_maybe_stop(txq, get_desc, stop_thrs, start_thrs) … \ /* Variant of netdev_tx_completed_queue() which guarantees smp_mb() if * @bytes != 0, regardless of kernel config. */ static inline void netdev_txq_completed_mb(struct netdev_queue *dev_queue, unsigned int pkts, unsigned int bytes) { … } /** * __netif_txq_completed_wake() - locklessly wake a Tx queue, if needed * @txq: struct netdev_queue to stop/start * @pkts: number of packets completed * @bytes: number of bytes completed * @get_desc: get current number of free descriptors (see requirements below!) * @start_thrs: minimal number of descriptors to re-enable the queue * @down_cond: down condition, predicate indicating that the queue should * not be woken up even if descriptors are available * * All arguments may be evaluated multiple times. * @get_desc must be a formula or a function call, it must always * return up-to-date information when evaluated! * Reports completed pkts/bytes to BQL. * * Returns: * 0 if the queue was woken up * 1 if the queue was already enabled (or disabled but @down_cond is true) * -1 if the queue was left unchanged (@start_thrs not reached) */ #define __netif_txq_completed_wake(txq, pkts, bytes, \ get_desc, start_thrs, down_cond) … #define netif_txq_completed_wake(txq, pkts, bytes, get_desc, start_thrs) … /* subqueue variants follow */ #define netif_subqueue_try_stop(dev, idx, get_desc, start_thrs) … #define netif_subqueue_maybe_stop(dev, idx, get_desc, stop_thrs, start_thrs) … #define netif_subqueue_completed_wake(dev, idx, pkts, bytes, \ get_desc, start_thrs) … #endif