1
2#ifndef __NET_SCHED_RED_H
3#define __NET_SCHED_RED_H
4
5#include <linux/types.h>
6#include <linux/bug.h>
7#include <net/pkt_sched.h>
8#include <net/inet_ecn.h>
9#include <net/dsfield.h>
10#include <linux/reciprocal_div.h>
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109
110#define RED_ONE_PERCENT ((u32)DIV_ROUND_CLOSEST(1ULL<<32, 100))
111
112#define MAX_P_MIN (1 * RED_ONE_PERCENT)
113#define MAX_P_MAX (50 * RED_ONE_PERCENT)
114#define MAX_P_ALPHA(val) min(MAX_P_MIN, val / 4)
115
116#define RED_STAB_SIZE 256
117#define RED_STAB_MASK (RED_STAB_SIZE - 1)
118
119struct red_stats {
120 u32 prob_drop;
121 u32 prob_mark;
122 u32 forced_drop;
123 u32 forced_mark;
124 u32 pdrop;
125 u32 other;
126};
127
128struct red_parms {
129
130 u32 qth_min;
131 u32 qth_max;
132 u32 Scell_max;
133 u32 max_P;
134
135 struct reciprocal_value max_P_reciprocal;
136 u32 qth_delta;
137 u32 target_min;
138 u32 target_max;
139 u8 Scell_log;
140 u8 Wlog;
141 u8 Plog;
142 u8 Stab[RED_STAB_SIZE];
143};
144
145struct red_vars {
146
147 int qcount;
148
149 u32 qR;
150
151 unsigned long qavg;
152 ktime_t qidlestart;
153};
154
155static inline u32 red_maxp(u8 Plog)
156{
157 return Plog < 32 ? (~0U >> Plog) : ~0U;
158}
159
160static inline void red_set_vars(struct red_vars *v)
161{
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166 v->qavg = 0;
167
168 v->qcount = -1;
169}
170
171static inline bool red_check_params(u32 qth_min, u32 qth_max, u8 Wlog)
172{
173 if (fls(qth_min) + Wlog > 32)
174 return false;
175 if (fls(qth_max) + Wlog > 32)
176 return false;
177 if (qth_max < qth_min)
178 return false;
179 return true;
180}
181
182static inline int red_get_flags(unsigned char qopt_flags,
183 unsigned char historic_mask,
184 struct nlattr *flags_attr,
185 unsigned char supported_mask,
186 struct nla_bitfield32 *p_flags,
187 unsigned char *p_userbits,
188 struct netlink_ext_ack *extack)
189{
190 struct nla_bitfield32 flags;
191
192 if (qopt_flags && flags_attr) {
193 NL_SET_ERR_MSG_MOD(extack, "flags should be passed either through qopt, or through a dedicated attribute");
194 return -EINVAL;
195 }
196
197 if (flags_attr) {
198 flags = nla_get_bitfield32(flags_attr);
199 } else {
200 flags.selector = historic_mask;
201 flags.value = qopt_flags & historic_mask;
202 }
203
204 *p_flags = flags;
205 *p_userbits = qopt_flags & ~historic_mask;
206 return 0;
207}
208
209static inline int red_validate_flags(unsigned char flags,
210 struct netlink_ext_ack *extack)
211{
212 if ((flags & TC_RED_NODROP) && !(flags & TC_RED_ECN)) {
213 NL_SET_ERR_MSG_MOD(extack, "nodrop mode is only meaningful with ECN");
214 return -EINVAL;
215 }
216
217 return 0;
218}
219
220static inline void red_set_parms(struct red_parms *p,
221 u32 qth_min, u32 qth_max, u8 Wlog, u8 Plog,
222 u8 Scell_log, u8 *stab, u32 max_P)
223{
224 int delta = qth_max - qth_min;
225 u32 max_p_delta;
226
227 p->qth_min = qth_min << Wlog;
228 p->qth_max = qth_max << Wlog;
229 p->Wlog = Wlog;
230 p->Plog = Plog;
231 if (delta <= 0)
232 delta = 1;
233 p->qth_delta = delta;
234 if (!max_P) {
235 max_P = red_maxp(Plog);
236 max_P *= delta;
237 }
238 p->max_P = max_P;
239 max_p_delta = max_P / delta;
240 max_p_delta = max(max_p_delta, 1U);
241 p->max_P_reciprocal = reciprocal_value(max_p_delta);
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247 delta /= 5;
248 p->target_min = qth_min + 2*delta;
249 p->target_max = qth_min + 3*delta;
250
251 p->Scell_log = Scell_log;
252 p->Scell_max = (255 << Scell_log);
253
254 if (stab)
255 memcpy(p->Stab, stab, sizeof(p->Stab));
256}
257
258static inline int red_is_idling(const struct red_vars *v)
259{
260 return v->qidlestart != 0;
261}
262
263static inline void red_start_of_idle_period(struct red_vars *v)
264{
265 v->qidlestart = ktime_get();
266}
267
268static inline void red_end_of_idle_period(struct red_vars *v)
269{
270 v->qidlestart = 0;
271}
272
273static inline void red_restart(struct red_vars *v)
274{
275 red_end_of_idle_period(v);
276 v->qavg = 0;
277 v->qcount = -1;
278}
279
280static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms *p,
281 const struct red_vars *v)
282{
283 s64 delta = ktime_us_delta(ktime_get(), v->qidlestart);
284 long us_idle = min_t(s64, delta, p->Scell_max);
285 int shift;
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307 shift = p->Stab[(us_idle >> p->Scell_log) & RED_STAB_MASK];
308
309 if (shift)
310 return v->qavg >> shift;
311 else {
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319 us_idle = (v->qavg * (u64)us_idle) >> p->Scell_log;
320
321 if (us_idle < (v->qavg >> 1))
322 return v->qavg - us_idle;
323 else
324 return v->qavg >> 1;
325 }
326}
327
328static inline unsigned long red_calc_qavg_no_idle_time(const struct red_parms *p,
329 const struct red_vars *v,
330 unsigned int backlog)
331{
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341 return v->qavg + (backlog - (v->qavg >> p->Wlog));
342}
343
344static inline unsigned long red_calc_qavg(const struct red_parms *p,
345 const struct red_vars *v,
346 unsigned int backlog)
347{
348 if (!red_is_idling(v))
349 return red_calc_qavg_no_idle_time(p, v, backlog);
350 else
351 return red_calc_qavg_from_idle_time(p, v);
352}
353
354
355static inline u32 red_random(const struct red_parms *p)
356{
357 return reciprocal_divide(prandom_u32(), p->max_P_reciprocal);
358}
359
360static inline int red_mark_probability(const struct red_parms *p,
361 const struct red_vars *v,
362 unsigned long qavg)
363{
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380 return !(((qavg - p->qth_min) >> p->Wlog) * v->qcount < v->qR);
381}
382
383enum {
384 RED_BELOW_MIN_THRESH,
385 RED_BETWEEN_TRESH,
386 RED_ABOVE_MAX_TRESH,
387};
388
389static inline int red_cmp_thresh(const struct red_parms *p, unsigned long qavg)
390{
391 if (qavg < p->qth_min)
392 return RED_BELOW_MIN_THRESH;
393 else if (qavg >= p->qth_max)
394 return RED_ABOVE_MAX_TRESH;
395 else
396 return RED_BETWEEN_TRESH;
397}
398
399enum {
400 RED_DONT_MARK,
401 RED_PROB_MARK,
402 RED_HARD_MARK,
403};
404
405static inline int red_action(const struct red_parms *p,
406 struct red_vars *v,
407 unsigned long qavg)
408{
409 switch (red_cmp_thresh(p, qavg)) {
410 case RED_BELOW_MIN_THRESH:
411 v->qcount = -1;
412 return RED_DONT_MARK;
413
414 case RED_BETWEEN_TRESH:
415 if (++v->qcount) {
416 if (red_mark_probability(p, v, qavg)) {
417 v->qcount = 0;
418 v->qR = red_random(p);
419 return RED_PROB_MARK;
420 }
421 } else
422 v->qR = red_random(p);
423
424 return RED_DONT_MARK;
425
426 case RED_ABOVE_MAX_TRESH:
427 v->qcount = -1;
428 return RED_HARD_MARK;
429 }
430
431 BUG();
432 return RED_DONT_MARK;
433}
434
435static inline void red_adaptative_algo(struct red_parms *p, struct red_vars *v)
436{
437 unsigned long qavg;
438 u32 max_p_delta;
439
440 qavg = v->qavg;
441 if (red_is_idling(v))
442 qavg = red_calc_qavg_from_idle_time(p, v);
443
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445 qavg >>= p->Wlog;
446
447 if (qavg > p->target_max && p->max_P <= MAX_P_MAX)
448 p->max_P += MAX_P_ALPHA(p->max_P);
449 else if (qavg < p->target_min && p->max_P >= MAX_P_MIN)
450 p->max_P = (p->max_P/10)*9;
451
452 max_p_delta = DIV_ROUND_CLOSEST(p->max_P, p->qth_delta);
453 max_p_delta = max(max_p_delta, 1U);
454 p->max_P_reciprocal = reciprocal_value(max_p_delta);
455}
456#endif
457