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/**
8 * struct netdev_config - queue-related configuration for a netdev
9 * @hds_thresh: HDS Threshold value.
10 * @hds_config: HDS value from userspace.
11 */
12struct netdev_config {
13 u32 hds_thresh;
14 u8 hds_config;
15};
16
17/* See the netdev.yaml spec for definition of each statistic */
18struct netdev_queue_stats_rx {
19 u64 bytes;
20 u64 packets;
21 u64 alloc_fail;
22
23 u64 hw_drops;
24 u64 hw_drop_overruns;
25
26 u64 csum_complete;
27 u64 csum_unnecessary;
28 u64 csum_none;
29 u64 csum_bad;
30
31 u64 hw_gro_packets;
32 u64 hw_gro_bytes;
33 u64 hw_gro_wire_packets;
34 u64 hw_gro_wire_bytes;
35
36 u64 hw_drop_ratelimits;
37};
38
39struct netdev_queue_stats_tx {
40 u64 bytes;
41 u64 packets;
42
43 u64 hw_drops;
44 u64 hw_drop_errors;
45
46 u64 csum_none;
47 u64 needs_csum;
48
49 u64 hw_gso_packets;
50 u64 hw_gso_bytes;
51 u64 hw_gso_wire_packets;
52 u64 hw_gso_wire_bytes;
53
54 u64 hw_drop_ratelimits;
55
56 u64 stop;
57 u64 wake;
58};
59
60/**
61 * struct netdev_stat_ops - netdev ops for fine grained stats
62 * @get_queue_stats_rx: get stats for a given Rx queue
63 * @get_queue_stats_tx: get stats for a given Tx queue
64 * @get_base_stats: get base stats (not belonging to any live instance)
65 *
66 * Query stats for a given object. The values of the statistics are undefined
67 * on entry (specifically they are *not* zero-initialized). Drivers should
68 * assign values only to the statistics they collect. Statistics which are not
69 * collected must be left undefined.
70 *
71 * Queue objects are not necessarily persistent, and only currently active
72 * queues are queried by the per-queue callbacks. This means that per-queue
73 * statistics will not generally add up to the total number of events for
74 * the device. The @get_base_stats callback allows filling in the delta
75 * between events for currently live queues and overall device history.
76 * @get_base_stats can also be used to report any miscellaneous packets
77 * transferred outside of the main set of queues used by the networking stack.
78 * When the statistics for the entire device are queried, first @get_base_stats
79 * is issued to collect the delta, and then a series of per-queue callbacks.
80 * Only statistics which are set in @get_base_stats will be reported
81 * at the device level, meaning that unlike in queue callbacks, setting
82 * a statistic to zero in @get_base_stats is a legitimate thing to do.
83 * This is because @get_base_stats has a second function of designating which
84 * statistics are in fact correct for the entire device (e.g. when history
85 * for some of the events is not maintained, and reliable "total" cannot
86 * be provided).
87 *
88 * Ops are called under the instance lock if netdev_need_ops_lock()
89 * returns true, otherwise under rtnl_lock.
90 * Device drivers can assume that when collecting total device stats,
91 * the @get_base_stats and subsequent per-queue calls are performed
92 * "atomically" (without releasing the relevant lock).
93 *
94 * Device drivers are encouraged to reset the per-queue statistics when
95 * number of queues change. This is because the primary use case for
96 * per-queue statistics is currently to detect traffic imbalance.
97 */
98struct netdev_stat_ops {
99 void (*get_queue_stats_rx)(struct net_device *dev, int idx,
100 struct netdev_queue_stats_rx *stats);
101 void (*get_queue_stats_tx)(struct net_device *dev, int idx,
102 struct netdev_queue_stats_tx *stats);
103 void (*get_base_stats)(struct net_device *dev,
104 struct netdev_queue_stats_rx *rx,
105 struct netdev_queue_stats_tx *tx);
106};
107
108void netdev_stat_queue_sum(struct net_device *netdev,
109 int rx_start, int rx_end,
110 struct netdev_queue_stats_rx *rx_sum,
111 int tx_start, int tx_end,
112 struct netdev_queue_stats_tx *tx_sum);
113
114/**
115 * struct netdev_queue_mgmt_ops - netdev ops for queue management
116 *
117 * @ndo_queue_mem_size: Size of the struct that describes a queue's memory.
118 *
119 * @ndo_queue_mem_alloc: Allocate memory for an RX queue at the specified index.
120 * The new memory is written at the specified address.
121 *
122 * @ndo_queue_mem_free: Free memory from an RX queue.
123 *
124 * @ndo_queue_start: Start an RX queue with the specified memory and at the
125 * specified index.
126 *
127 * @ndo_queue_stop: Stop the RX queue at the specified index. The stopped
128 * queue's memory is written at the specified address.
129 *
130 * Note that @ndo_queue_mem_alloc and @ndo_queue_mem_free may be called while
131 * the interface is closed. @ndo_queue_start and @ndo_queue_stop will only
132 * be called for an interface which is open.
133 */
134struct netdev_queue_mgmt_ops {
135 size_t ndo_queue_mem_size;
136 int (*ndo_queue_mem_alloc)(struct net_device *dev,
137 void *per_queue_mem,
138 int idx);
139 void (*ndo_queue_mem_free)(struct net_device *dev,
140 void *per_queue_mem);
141 int (*ndo_queue_start)(struct net_device *dev,
142 void *per_queue_mem,
143 int idx);
144 int (*ndo_queue_stop)(struct net_device *dev,
145 void *per_queue_mem,
146 int idx);
147};
148
149/**
150 * DOC: Lockless queue stopping / waking helpers.
151 *
152 * The netif_txq_maybe_stop() and __netif_txq_completed_wake()
153 * macros are designed to safely implement stopping
154 * and waking netdev queues without full lock protection.
155 *
156 * We assume that there can be no concurrent stop attempts and no concurrent
157 * wake attempts. The try-stop should happen from the xmit handler,
158 * while wake up should be triggered from NAPI poll context.
159 * The two may run concurrently (single producer, single consumer).
160 *
161 * The try-stop side is expected to run from the xmit handler and therefore
162 * it does not reschedule Tx (netif_tx_start_queue() instead of
163 * netif_tx_wake_queue()). Uses of the ``stop`` macros outside of the xmit
164 * handler may lead to xmit queue being enabled but not run.
165 * The waking side does not have similar context restrictions.
166 *
167 * The macros guarantee that rings will not remain stopped if there's
168 * space available, but they do *not* prevent false wake ups when
169 * the ring is full! Drivers should check for ring full at the start
170 * for the xmit handler.
171 *
172 * All descriptor ring indexes (and other relevant shared state) must
173 * be updated before invoking the macros.
174 */
175
176#define netif_txq_try_stop(txq, get_desc, start_thrs) \
177 ({ \
178 int _res; \
179 \
180 netif_tx_stop_queue(txq); \
181 /* Producer index and stop bit must be visible \
182 * to consumer before we recheck. \
183 * Pairs with a barrier in __netif_txq_completed_wake(). \
184 */ \
185 smp_mb__after_atomic(); \
186 \
187 /* We need to check again in a case another \
188 * CPU has just made room available. \
189 */ \
190 _res = 0; \
191 if (unlikely(get_desc >= start_thrs)) { \
192 netif_tx_start_queue(txq); \
193 _res = -1; \
194 } \
195 _res; \
196 }) \
197
198/**
199 * netif_txq_maybe_stop() - locklessly stop a Tx queue, if needed
200 * @txq: struct netdev_queue to stop/start
201 * @get_desc: get current number of free descriptors (see requirements below!)
202 * @stop_thrs: minimal number of available descriptors for queue to be left
203 * enabled
204 * @start_thrs: minimal number of descriptors to re-enable the queue, can be
205 * equal to @stop_thrs or higher to avoid frequent waking
206 *
207 * All arguments may be evaluated multiple times, beware of side effects.
208 * @get_desc must be a formula or a function call, it must always
209 * return up-to-date information when evaluated!
210 * Expected to be used from ndo_start_xmit, see the comment on top of the file.
211 *
212 * Returns:
213 * 0 if the queue was stopped
214 * 1 if the queue was left enabled
215 * -1 if the queue was re-enabled (raced with waking)
216 */
217#define netif_txq_maybe_stop(txq, get_desc, stop_thrs, start_thrs) \
218 ({ \
219 int _res; \
220 \
221 _res = 1; \
222 if (unlikely(get_desc < stop_thrs)) \
223 _res = netif_txq_try_stop(txq, get_desc, start_thrs); \
224 _res; \
225 }) \
226
227/* Variant of netdev_tx_completed_queue() which guarantees smp_mb() if
228 * @bytes != 0, regardless of kernel config.
229 */
230static inline void
231netdev_txq_completed_mb(struct netdev_queue *dev_queue,
232 unsigned int pkts, unsigned int bytes)
233{
234 if (IS_ENABLED(CONFIG_BQL))
235 netdev_tx_completed_queue(dev_queue, pkts, bytes);
236 else if (bytes)
237 smp_mb();
238}
239
240/**
241 * __netif_txq_completed_wake() - locklessly wake a Tx queue, if needed
242 * @txq: struct netdev_queue to stop/start
243 * @pkts: number of packets completed
244 * @bytes: number of bytes completed
245 * @get_desc: get current number of free descriptors (see requirements below!)
246 * @start_thrs: minimal number of descriptors to re-enable the queue
247 * @down_cond: down condition, predicate indicating that the queue should
248 * not be woken up even if descriptors are available
249 *
250 * All arguments may be evaluated multiple times.
251 * @get_desc must be a formula or a function call, it must always
252 * return up-to-date information when evaluated!
253 * Reports completed pkts/bytes to BQL.
254 *
255 * Returns:
256 * 0 if the queue was woken up
257 * 1 if the queue was already enabled (or disabled but @down_cond is true)
258 * -1 if the queue was left unchanged (@start_thrs not reached)
259 */
260#define __netif_txq_completed_wake(txq, pkts, bytes, \
261 get_desc, start_thrs, down_cond) \
262 ({ \
263 int _res; \
264 \
265 /* Report to BQL and piggy back on its barrier. \
266 * Barrier makes sure that anybody stopping the queue \
267 * after this point sees the new consumer index. \
268 * Pairs with barrier in netif_txq_try_stop(). \
269 */ \
270 netdev_txq_completed_mb(txq, pkts, bytes); \
271 \
272 _res = -1; \
273 if (pkts && likely(get_desc >= start_thrs)) { \
274 _res = 1; \
275 if (unlikely(netif_tx_queue_stopped(txq)) && \
276 !(down_cond)) { \
277 netif_tx_wake_queue(txq); \
278 _res = 0; \
279 } \
280 } \
281 _res; \
282 })
283
284#define netif_txq_completed_wake(txq, pkts, bytes, get_desc, start_thrs) \
285 __netif_txq_completed_wake(txq, pkts, bytes, get_desc, start_thrs, false)
286
287/* subqueue variants follow */
288
289#define netif_subqueue_try_stop(dev, idx, get_desc, start_thrs) \
290 ({ \
291 struct netdev_queue *_txq; \
292 \
293 _txq = netdev_get_tx_queue(dev, idx); \
294 netif_txq_try_stop(_txq, get_desc, start_thrs); \
295 })
296
297#define netif_subqueue_maybe_stop(dev, idx, get_desc, stop_thrs, start_thrs) \
298 ({ \
299 struct netdev_queue *_txq; \
300 \
301 _txq = netdev_get_tx_queue(dev, idx); \
302 netif_txq_maybe_stop(_txq, get_desc, stop_thrs, start_thrs); \
303 })
304
305#define netif_subqueue_completed_wake(dev, idx, pkts, bytes, \
306 get_desc, start_thrs) \
307 ({ \
308 struct netdev_queue *_txq; \
309 \
310 _txq = netdev_get_tx_queue(dev, idx); \
311 netif_txq_completed_wake(_txq, pkts, bytes, \
312 get_desc, start_thrs); \
313 })
314
315#endif
316

source code of linux/include/net/netdev_queues.h