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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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 u8 Scell_log, u8 *stab)
173{
174 if (fls(qth_min) + Wlog >= 32)
175 return false;
176 if (fls(qth_max) + Wlog >= 32)
177 return false;
178 if (Scell_log >= 32)
179 return false;
180 if (qth_max < qth_min)
181 return false;
182 if (stab) {
183 int i;
184
185 for (i = 0; i < RED_STAB_SIZE; i++)
186 if (stab[i] >= 32)
187 return false;
188 }
189 return true;
190}
191
192static inline int red_get_flags(unsigned char qopt_flags,
193 unsigned char historic_mask,
194 struct nlattr *flags_attr,
195 unsigned char supported_mask,
196 struct nla_bitfield32 *p_flags,
197 unsigned char *p_userbits,
198 struct netlink_ext_ack *extack)
199{
200 struct nla_bitfield32 flags;
201
202 if (qopt_flags && flags_attr) {
203 NL_SET_ERR_MSG_MOD(extack, "flags should be passed either through qopt, or through a dedicated attribute");
204 return -EINVAL;
205 }
206
207 if (flags_attr) {
208 flags = nla_get_bitfield32(flags_attr);
209 } else {
210 flags.selector = historic_mask;
211 flags.value = qopt_flags & historic_mask;
212 }
213
214 *p_flags = flags;
215 *p_userbits = qopt_flags & ~historic_mask;
216 return 0;
217}
218
219static inline int red_validate_flags(unsigned char flags,
220 struct netlink_ext_ack *extack)
221{
222 if ((flags & TC_RED_NODROP) && !(flags & TC_RED_ECN)) {
223 NL_SET_ERR_MSG_MOD(extack, "nodrop mode is only meaningful with ECN");
224 return -EINVAL;
225 }
226
227 return 0;
228}
229
230static inline void red_set_parms(struct red_parms *p,
231 u32 qth_min, u32 qth_max, u8 Wlog, u8 Plog,
232 u8 Scell_log, u8 *stab, u32 max_P)
233{
234 int delta = qth_max - qth_min;
235 u32 max_p_delta;
236
237 p->qth_min = qth_min << Wlog;
238 p->qth_max = qth_max << Wlog;
239 p->Wlog = Wlog;
240 p->Plog = Plog;
241 if (delta <= 0)
242 delta = 1;
243 p->qth_delta = delta;
244 if (!max_P) {
245 max_P = red_maxp(Plog);
246 max_P *= delta;
247 }
248 p->max_P = max_P;
249 max_p_delta = max_P / delta;
250 max_p_delta = max(max_p_delta, 1U);
251 p->max_P_reciprocal = reciprocal_value(max_p_delta);
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257 delta /= 5;
258 p->target_min = qth_min + 2*delta;
259 p->target_max = qth_min + 3*delta;
260
261 p->Scell_log = Scell_log;
262 p->Scell_max = (255 << Scell_log);
263
264 if (stab)
265 memcpy(p->Stab, stab, sizeof(p->Stab));
266}
267
268static inline int red_is_idling(const struct red_vars *v)
269{
270 return v->qidlestart != 0;
271}
272
273static inline void red_start_of_idle_period(struct red_vars *v)
274{
275 v->qidlestart = ktime_get();
276}
277
278static inline void red_end_of_idle_period(struct red_vars *v)
279{
280 v->qidlestart = 0;
281}
282
283static inline void red_restart(struct red_vars *v)
284{
285 red_end_of_idle_period(v);
286 v->qavg = 0;
287 v->qcount = -1;
288}
289
290static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms *p,
291 const struct red_vars *v)
292{
293 s64 delta = ktime_us_delta(ktime_get(), v->qidlestart);
294 long us_idle = min_t(s64, delta, p->Scell_max);
295 int shift;
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317 shift = p->Stab[(us_idle >> p->Scell_log) & RED_STAB_MASK];
318
319 if (shift)
320 return v->qavg >> shift;
321 else {
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329 us_idle = (v->qavg * (u64)us_idle) >> p->Scell_log;
330
331 if (us_idle < (v->qavg >> 1))
332 return v->qavg - us_idle;
333 else
334 return v->qavg >> 1;
335 }
336}
337
338static inline unsigned long red_calc_qavg_no_idle_time(const struct red_parms *p,
339 const struct red_vars *v,
340 unsigned int backlog)
341{
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351 return v->qavg + (backlog - (v->qavg >> p->Wlog));
352}
353
354static inline unsigned long red_calc_qavg(const struct red_parms *p,
355 const struct red_vars *v,
356 unsigned int backlog)
357{
358 if (!red_is_idling(v))
359 return red_calc_qavg_no_idle_time(p, v, backlog);
360 else
361 return red_calc_qavg_from_idle_time(p, v);
362}
363
364
365static inline u32 red_random(const struct red_parms *p)
366{
367 return reciprocal_divide(prandom_u32(), p->max_P_reciprocal);
368}
369
370static inline int red_mark_probability(const struct red_parms *p,
371 const struct red_vars *v,
372 unsigned long qavg)
373{
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390 return !(((qavg - p->qth_min) >> p->Wlog) * v->qcount < v->qR);
391}
392
393enum {
394 RED_BELOW_MIN_THRESH,
395 RED_BETWEEN_TRESH,
396 RED_ABOVE_MAX_TRESH,
397};
398
399static inline int red_cmp_thresh(const struct red_parms *p, unsigned long qavg)
400{
401 if (qavg < p->qth_min)
402 return RED_BELOW_MIN_THRESH;
403 else if (qavg >= p->qth_max)
404 return RED_ABOVE_MAX_TRESH;
405 else
406 return RED_BETWEEN_TRESH;
407}
408
409enum {
410 RED_DONT_MARK,
411 RED_PROB_MARK,
412 RED_HARD_MARK,
413};
414
415static inline int red_action(const struct red_parms *p,
416 struct red_vars *v,
417 unsigned long qavg)
418{
419 switch (red_cmp_thresh(p, qavg)) {
420 case RED_BELOW_MIN_THRESH:
421 v->qcount = -1;
422 return RED_DONT_MARK;
423
424 case RED_BETWEEN_TRESH:
425 if (++v->qcount) {
426 if (red_mark_probability(p, v, qavg)) {
427 v->qcount = 0;
428 v->qR = red_random(p);
429 return RED_PROB_MARK;
430 }
431 } else
432 v->qR = red_random(p);
433
434 return RED_DONT_MARK;
435
436 case RED_ABOVE_MAX_TRESH:
437 v->qcount = -1;
438 return RED_HARD_MARK;
439 }
440
441 BUG();
442 return RED_DONT_MARK;
443}
444
445static inline void red_adaptative_algo(struct red_parms *p, struct red_vars *v)
446{
447 unsigned long qavg;
448 u32 max_p_delta;
449
450 qavg = v->qavg;
451 if (red_is_idling(v))
452 qavg = red_calc_qavg_from_idle_time(p, v);
453
454
455 qavg >>= p->Wlog;
456
457 if (qavg > p->target_max && p->max_P <= MAX_P_MAX)
458 p->max_P += MAX_P_ALPHA(p->max_P);
459 else if (qavg < p->target_min && p->max_P >= MAX_P_MIN)
460 p->max_P = (p->max_P/10)*9;
461
462 max_p_delta = DIV_ROUND_CLOSEST(p->max_P, p->qth_delta);
463 max_p_delta = max(max_p_delta, 1U);
464 p->max_P_reciprocal = reciprocal_value(max_p_delta);
465}
466#endif
467