1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_NET_QUEUES_H 3 #define _LINUX_NET_QUEUES_H 4 5 #include <linux/netdevice.h> 6 7 /* See the netdev.yaml spec for definition of each statistic */ 8 struct netdev_queue_stats_rx { 9 u64 bytes; 10 u64 packets; 11 u64 alloc_fail; 12 13 u64 hw_drops; 14 u64 hw_drop_overruns; 15 16 u64 csum_unnecessary; 17 u64 csum_none; 18 u64 csum_bad; 19 20 u64 hw_gro_packets; 21 u64 hw_gro_bytes; 22 u64 hw_gro_wire_packets; 23 u64 hw_gro_wire_bytes; 24 25 u64 hw_drop_ratelimits; 26 }; 27 28 struct netdev_queue_stats_tx { 29 u64 bytes; 30 u64 packets; 31 32 u64 hw_drops; 33 u64 hw_drop_errors; 34 35 u64 csum_none; 36 u64 needs_csum; 37 38 u64 hw_gso_packets; 39 u64 hw_gso_bytes; 40 u64 hw_gso_wire_packets; 41 u64 hw_gso_wire_bytes; 42 43 u64 hw_drop_ratelimits; 44 }; 45 46 /** 47 * struct netdev_stat_ops - netdev ops for fine grained stats 48 * @get_queue_stats_rx: get stats for a given Rx queue 49 * @get_queue_stats_tx: get stats for a given Tx queue 50 * @get_base_stats: get base stats (not belonging to any live instance) 51 * 52 * Query stats for a given object. The values of the statistics are undefined 53 * on entry (specifically they are *not* zero-initialized). Drivers should 54 * assign values only to the statistics they collect. Statistics which are not 55 * collected must be left undefined. 56 * 57 * Queue objects are not necessarily persistent, and only currently active 58 * queues are queried by the per-queue callbacks. This means that per-queue 59 * statistics will not generally add up to the total number of events for 60 * the device. The @get_base_stats callback allows filling in the delta 61 * between events for currently live queues and overall device history. 62 * When the statistics for the entire device are queried, first @get_base_stats 63 * is issued to collect the delta, and then a series of per-queue callbacks. 64 * Only statistics which are set in @get_base_stats will be reported 65 * at the device level, meaning that unlike in queue callbacks, setting 66 * a statistic to zero in @get_base_stats is a legitimate thing to do. 67 * This is because @get_base_stats has a second function of designating which 68 * statistics are in fact correct for the entire device (e.g. when history 69 * for some of the events is not maintained, and reliable "total" cannot 70 * be provided). 71 * 72 * Device drivers can assume that when collecting total device stats, 73 * the @get_base_stats and subsequent per-queue calls are performed 74 * "atomically" (without releasing the rtnl_lock). 75 * 76 * Device drivers are encouraged to reset the per-queue statistics when 77 * number of queues change. This is because the primary use case for 78 * per-queue statistics is currently to detect traffic imbalance. 79 */ 80 struct netdev_stat_ops { 81 void (*get_queue_stats_rx)(struct net_device *dev, int idx, 82 struct netdev_queue_stats_rx *stats); 83 void (*get_queue_stats_tx)(struct net_device *dev, int idx, 84 struct netdev_queue_stats_tx *stats); 85 void (*get_base_stats)(struct net_device *dev, 86 struct netdev_queue_stats_rx *rx, 87 struct netdev_queue_stats_tx *tx); 88 }; 89 90 /** 91 * struct netdev_queue_mgmt_ops - netdev ops for queue management 92 * 93 * @ndo_queue_mem_size: Size of the struct that describes a queue's memory. 94 * 95 * @ndo_queue_mem_alloc: Allocate memory for an RX queue at the specified index. 96 * The new memory is written at the specified address. 97 * 98 * @ndo_queue_mem_free: Free memory from an RX queue. 99 * 100 * @ndo_queue_start: Start an RX queue with the specified memory and at the 101 * specified index. 102 * 103 * @ndo_queue_stop: Stop the RX queue at the specified index. The stopped 104 * queue's memory is written at the specified address. 105 */ 106 struct netdev_queue_mgmt_ops { 107 size_t ndo_queue_mem_size; 108 int (*ndo_queue_mem_alloc)(struct net_device *dev, 109 void *per_queue_mem, 110 int idx); 111 void (*ndo_queue_mem_free)(struct net_device *dev, 112 void *per_queue_mem); 113 int (*ndo_queue_start)(struct net_device *dev, 114 void *per_queue_mem, 115 int idx); 116 int (*ndo_queue_stop)(struct net_device *dev, 117 void *per_queue_mem, 118 int idx); 119 }; 120 121 /** 122 * DOC: Lockless queue stopping / waking helpers. 123 * 124 * The netif_txq_maybe_stop() and __netif_txq_completed_wake() 125 * macros are designed to safely implement stopping 126 * and waking netdev queues without full lock protection. 127 * 128 * We assume that there can be no concurrent stop attempts and no concurrent 129 * wake attempts. The try-stop should happen from the xmit handler, 130 * while wake up should be triggered from NAPI poll context. 131 * The two may run concurrently (single producer, single consumer). 132 * 133 * The try-stop side is expected to run from the xmit handler and therefore 134 * it does not reschedule Tx (netif_tx_start_queue() instead of 135 * netif_tx_wake_queue()). Uses of the ``stop`` macros outside of the xmit 136 * handler may lead to xmit queue being enabled but not run. 137 * The waking side does not have similar context restrictions. 138 * 139 * The macros guarantee that rings will not remain stopped if there's 140 * space available, but they do *not* prevent false wake ups when 141 * the ring is full! Drivers should check for ring full at the start 142 * for the xmit handler. 143 * 144 * All descriptor ring indexes (and other relevant shared state) must 145 * be updated before invoking the macros. 146 */ 147 148 #define netif_txq_try_stop(txq, get_desc, start_thrs) \ 149 ({ \ 150 int _res; \ 151 \ 152 netif_tx_stop_queue(txq); \ 153 /* Producer index and stop bit must be visible \ 154 * to consumer before we recheck. \ 155 * Pairs with a barrier in __netif_txq_completed_wake(). \ 156 */ \ 157 smp_mb__after_atomic(); \ 158 \ 159 /* We need to check again in a case another \ 160 * CPU has just made room available. \ 161 */ \ 162 _res = 0; \ 163 if (unlikely(get_desc >= start_thrs)) { \ 164 netif_tx_start_queue(txq); \ 165 _res = -1; \ 166 } \ 167 _res; \ 168 }) \ 169 170 /** 171 * netif_txq_maybe_stop() - locklessly stop a Tx queue, if needed 172 * @txq: struct netdev_queue to stop/start 173 * @get_desc: get current number of free descriptors (see requirements below!) 174 * @stop_thrs: minimal number of available descriptors for queue to be left 175 * enabled 176 * @start_thrs: minimal number of descriptors to re-enable the queue, can be 177 * equal to @stop_thrs or higher to avoid frequent waking 178 * 179 * All arguments may be evaluated multiple times, beware of side effects. 180 * @get_desc must be a formula or a function call, it must always 181 * return up-to-date information when evaluated! 182 * Expected to be used from ndo_start_xmit, see the comment on top of the file. 183 * 184 * Returns: 185 * 0 if the queue was stopped 186 * 1 if the queue was left enabled 187 * -1 if the queue was re-enabled (raced with waking) 188 */ 189 #define netif_txq_maybe_stop(txq, get_desc, stop_thrs, start_thrs) \ 190 ({ \ 191 int _res; \ 192 \ 193 _res = 1; \ 194 if (unlikely(get_desc < stop_thrs)) \ 195 _res = netif_txq_try_stop(txq, get_desc, start_thrs); \ 196 _res; \ 197 }) \ 198 199 /* Variant of netdev_tx_completed_queue() which guarantees smp_mb() if 200 * @bytes != 0, regardless of kernel config. 201 */ 202 static inline void 203 netdev_txq_completed_mb(struct netdev_queue *dev_queue, 204 unsigned int pkts, unsigned int bytes) 205 { 206 if (IS_ENABLED(CONFIG_BQL)) 207 netdev_tx_completed_queue(dev_queue, pkts, bytes); 208 else if (bytes) 209 smp_mb(); 210 } 211 212 /** 213 * __netif_txq_completed_wake() - locklessly wake a Tx queue, if needed 214 * @txq: struct netdev_queue to stop/start 215 * @pkts: number of packets completed 216 * @bytes: number of bytes completed 217 * @get_desc: get current number of free descriptors (see requirements below!) 218 * @start_thrs: minimal number of descriptors to re-enable the queue 219 * @down_cond: down condition, predicate indicating that the queue should 220 * not be woken up even if descriptors are available 221 * 222 * All arguments may be evaluated multiple times. 223 * @get_desc must be a formula or a function call, it must always 224 * return up-to-date information when evaluated! 225 * Reports completed pkts/bytes to BQL. 226 * 227 * Returns: 228 * 0 if the queue was woken up 229 * 1 if the queue was already enabled (or disabled but @down_cond is true) 230 * -1 if the queue was left unchanged (@start_thrs not reached) 231 */ 232 #define __netif_txq_completed_wake(txq, pkts, bytes, \ 233 get_desc, start_thrs, down_cond) \ 234 ({ \ 235 int _res; \ 236 \ 237 /* Report to BQL and piggy back on its barrier. \ 238 * Barrier makes sure that anybody stopping the queue \ 239 * after this point sees the new consumer index. \ 240 * Pairs with barrier in netif_txq_try_stop(). \ 241 */ \ 242 netdev_txq_completed_mb(txq, pkts, bytes); \ 243 \ 244 _res = -1; \ 245 if (pkts && likely(get_desc >= start_thrs)) { \ 246 _res = 1; \ 247 if (unlikely(netif_tx_queue_stopped(txq)) && \ 248 !(down_cond)) { \ 249 netif_tx_wake_queue(txq); \ 250 _res = 0; \ 251 } \ 252 } \ 253 _res; \ 254 }) 255 256 #define netif_txq_completed_wake(txq, pkts, bytes, get_desc, start_thrs) \ 257 __netif_txq_completed_wake(txq, pkts, bytes, get_desc, start_thrs, false) 258 259 /* subqueue variants follow */ 260 261 #define netif_subqueue_try_stop(dev, idx, get_desc, start_thrs) \ 262 ({ \ 263 struct netdev_queue *txq; \ 264 \ 265 txq = netdev_get_tx_queue(dev, idx); \ 266 netif_txq_try_stop(txq, get_desc, start_thrs); \ 267 }) 268 269 #define netif_subqueue_maybe_stop(dev, idx, get_desc, stop_thrs, start_thrs) \ 270 ({ \ 271 struct netdev_queue *txq; \ 272 \ 273 txq = netdev_get_tx_queue(dev, idx); \ 274 netif_txq_maybe_stop(txq, get_desc, stop_thrs, start_thrs); \ 275 }) 276 277 #define netif_subqueue_completed_wake(dev, idx, pkts, bytes, \ 278 get_desc, start_thrs) \ 279 ({ \ 280 struct netdev_queue *txq; \ 281 \ 282 txq = netdev_get_tx_queue(dev, idx); \ 283 netif_txq_completed_wake(txq, pkts, bytes, \ 284 get_desc, start_thrs); \ 285 }) 286 287 #endif 288