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 */
12 struct netdev_config {
13 u32 hds_thresh;
14 u8 hds_config;
15 };
16
17 /* See the netdev.yaml spec for definition of each statistic */
18 struct 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
39 struct 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 * Device drivers can assume that when collecting total device stats,
89 * the @get_base_stats and subsequent per-queue calls are performed
90 * "atomically" (without releasing the rtnl_lock).
91 *
92 * Device drivers are encouraged to reset the per-queue statistics when
93 * number of queues change. This is because the primary use case for
94 * per-queue statistics is currently to detect traffic imbalance.
95 */
96 struct netdev_stat_ops {
97 void (*get_queue_stats_rx)(struct net_device *dev, int idx,
98 struct netdev_queue_stats_rx *stats);
99 void (*get_queue_stats_tx)(struct net_device *dev, int idx,
100 struct netdev_queue_stats_tx *stats);
101 void (*get_base_stats)(struct net_device *dev,
102 struct netdev_queue_stats_rx *rx,
103 struct netdev_queue_stats_tx *tx);
104 };
105
106 /**
107 * struct netdev_queue_mgmt_ops - netdev ops for queue management
108 *
109 * @ndo_queue_mem_size: Size of the struct that describes a queue's memory.
110 *
111 * @ndo_queue_mem_alloc: Allocate memory for an RX queue at the specified index.
112 * The new memory is written at the specified address.
113 *
114 * @ndo_queue_mem_free: Free memory from an RX queue.
115 *
116 * @ndo_queue_start: Start an RX queue with the specified memory and at the
117 * specified index.
118 *
119 * @ndo_queue_stop: Stop the RX queue at the specified index. The stopped
120 * queue's memory is written at the specified address.
121 *
122 * Note that @ndo_queue_mem_alloc and @ndo_queue_mem_free may be called while
123 * the interface is closed. @ndo_queue_start and @ndo_queue_stop will only
124 * be called for an interface which is open.
125 */
126 struct netdev_queue_mgmt_ops {
127 size_t ndo_queue_mem_size;
128 int (*ndo_queue_mem_alloc)(struct net_device *dev,
129 void *per_queue_mem,
130 int idx);
131 void (*ndo_queue_mem_free)(struct net_device *dev,
132 void *per_queue_mem);
133 int (*ndo_queue_start)(struct net_device *dev,
134 void *per_queue_mem,
135 int idx);
136 int (*ndo_queue_stop)(struct net_device *dev,
137 void *per_queue_mem,
138 int idx);
139 };
140
141 /**
142 * DOC: Lockless queue stopping / waking helpers.
143 *
144 * The netif_txq_maybe_stop() and __netif_txq_completed_wake()
145 * macros are designed to safely implement stopping
146 * and waking netdev queues without full lock protection.
147 *
148 * We assume that there can be no concurrent stop attempts and no concurrent
149 * wake attempts. The try-stop should happen from the xmit handler,
150 * while wake up should be triggered from NAPI poll context.
151 * The two may run concurrently (single producer, single consumer).
152 *
153 * The try-stop side is expected to run from the xmit handler and therefore
154 * it does not reschedule Tx (netif_tx_start_queue() instead of
155 * netif_tx_wake_queue()). Uses of the ``stop`` macros outside of the xmit
156 * handler may lead to xmit queue being enabled but not run.
157 * The waking side does not have similar context restrictions.
158 *
159 * The macros guarantee that rings will not remain stopped if there's
160 * space available, but they do *not* prevent false wake ups when
161 * the ring is full! Drivers should check for ring full at the start
162 * for the xmit handler.
163 *
164 * All descriptor ring indexes (and other relevant shared state) must
165 * be updated before invoking the macros.
166 */
167
168 #define netif_txq_try_stop(txq, get_desc, start_thrs) \
169 ({ \
170 int _res; \
171 \
172 netif_tx_stop_queue(txq); \
173 /* Producer index and stop bit must be visible \
174 * to consumer before we recheck. \
175 * Pairs with a barrier in __netif_txq_completed_wake(). \
176 */ \
177 smp_mb__after_atomic(); \
178 \
179 /* We need to check again in a case another \
180 * CPU has just made room available. \
181 */ \
182 _res = 0; \
183 if (unlikely(get_desc >= start_thrs)) { \
184 netif_tx_start_queue(txq); \
185 _res = -1; \
186 } \
187 _res; \
188 }) \
189
190 /**
191 * netif_txq_maybe_stop() - locklessly stop a Tx queue, if needed
192 * @txq: struct netdev_queue to stop/start
193 * @get_desc: get current number of free descriptors (see requirements below!)
194 * @stop_thrs: minimal number of available descriptors for queue to be left
195 * enabled
196 * @start_thrs: minimal number of descriptors to re-enable the queue, can be
197 * equal to @stop_thrs or higher to avoid frequent waking
198 *
199 * All arguments may be evaluated multiple times, beware of side effects.
200 * @get_desc must be a formula or a function call, it must always
201 * return up-to-date information when evaluated!
202 * Expected to be used from ndo_start_xmit, see the comment on top of the file.
203 *
204 * Returns:
205 * 0 if the queue was stopped
206 * 1 if the queue was left enabled
207 * -1 if the queue was re-enabled (raced with waking)
208 */
209 #define netif_txq_maybe_stop(txq, get_desc, stop_thrs, start_thrs) \
210 ({ \
211 int _res; \
212 \
213 _res = 1; \
214 if (unlikely(get_desc < stop_thrs)) \
215 _res = netif_txq_try_stop(txq, get_desc, start_thrs); \
216 _res; \
217 }) \
218
219 /* Variant of netdev_tx_completed_queue() which guarantees smp_mb() if
220 * @bytes != 0, regardless of kernel config.
221 */
222 static inline void
netdev_txq_completed_mb(struct netdev_queue * dev_queue,unsigned int pkts,unsigned int bytes)223 netdev_txq_completed_mb(struct netdev_queue *dev_queue,
224 unsigned int pkts, unsigned int bytes)
225 {
226 if (IS_ENABLED(CONFIG_BQL))
227 netdev_tx_completed_queue(dev_queue, pkts, bytes);
228 else if (bytes)
229 smp_mb();
230 }
231
232 /**
233 * __netif_txq_completed_wake() - locklessly wake a Tx queue, if needed
234 * @txq: struct netdev_queue to stop/start
235 * @pkts: number of packets completed
236 * @bytes: number of bytes completed
237 * @get_desc: get current number of free descriptors (see requirements below!)
238 * @start_thrs: minimal number of descriptors to re-enable the queue
239 * @down_cond: down condition, predicate indicating that the queue should
240 * not be woken up even if descriptors are available
241 *
242 * All arguments may be evaluated multiple times.
243 * @get_desc must be a formula or a function call, it must always
244 * return up-to-date information when evaluated!
245 * Reports completed pkts/bytes to BQL.
246 *
247 * Returns:
248 * 0 if the queue was woken up
249 * 1 if the queue was already enabled (or disabled but @down_cond is true)
250 * -1 if the queue was left unchanged (@start_thrs not reached)
251 */
252 #define __netif_txq_completed_wake(txq, pkts, bytes, \
253 get_desc, start_thrs, down_cond) \
254 ({ \
255 int _res; \
256 \
257 /* Report to BQL and piggy back on its barrier. \
258 * Barrier makes sure that anybody stopping the queue \
259 * after this point sees the new consumer index. \
260 * Pairs with barrier in netif_txq_try_stop(). \
261 */ \
262 netdev_txq_completed_mb(txq, pkts, bytes); \
263 \
264 _res = -1; \
265 if (pkts && likely(get_desc >= start_thrs)) { \
266 _res = 1; \
267 if (unlikely(netif_tx_queue_stopped(txq)) && \
268 !(down_cond)) { \
269 netif_tx_wake_queue(txq); \
270 _res = 0; \
271 } \
272 } \
273 _res; \
274 })
275
276 #define netif_txq_completed_wake(txq, pkts, bytes, get_desc, start_thrs) \
277 __netif_txq_completed_wake(txq, pkts, bytes, get_desc, start_thrs, false)
278
279 /* subqueue variants follow */
280
281 #define netif_subqueue_try_stop(dev, idx, get_desc, start_thrs) \
282 ({ \
283 struct netdev_queue *txq; \
284 \
285 txq = netdev_get_tx_queue(dev, idx); \
286 netif_txq_try_stop(txq, get_desc, start_thrs); \
287 })
288
289 #define netif_subqueue_maybe_stop(dev, idx, get_desc, stop_thrs, start_thrs) \
290 ({ \
291 struct netdev_queue *txq; \
292 \
293 txq = netdev_get_tx_queue(dev, idx); \
294 netif_txq_maybe_stop(txq, get_desc, stop_thrs, start_thrs); \
295 })
296
297 #define netif_subqueue_completed_wake(dev, idx, pkts, bytes, \
298 get_desc, start_thrs) \
299 ({ \
300 struct netdev_queue *txq; \
301 \
302 txq = netdev_get_tx_queue(dev, idx); \
303 netif_txq_completed_wake(txq, pkts, bytes, \
304 get_desc, start_thrs); \
305 })
306
307 #endif
308