Root/
1 | /* |
2 | * Read-Copy Update mechanism for mutual exclusion (tree-based version) |
3 | * Internal non-public definitions. |
4 | * |
5 | * This program is free software; you can redistribute it and/or modify |
6 | * it under the terms of the GNU General Public License as published by |
7 | * the Free Software Foundation; either version 2 of the License, or |
8 | * (at your option) any later version. |
9 | * |
10 | * This program is distributed in the hope that it will be useful, |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
13 | * GNU General Public License for more details. |
14 | * |
15 | * You should have received a copy of the GNU General Public License |
16 | * along with this program; if not, write to the Free Software |
17 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
18 | * |
19 | * Copyright IBM Corporation, 2008 |
20 | * |
21 | * Author: Ingo Molnar <mingo@elte.hu> |
22 | * Paul E. McKenney <paulmck@linux.vnet.ibm.com> |
23 | */ |
24 | |
25 | #include <linux/cache.h> |
26 | #include <linux/spinlock.h> |
27 | #include <linux/threads.h> |
28 | #include <linux/cpumask.h> |
29 | #include <linux/seqlock.h> |
30 | |
31 | /* |
32 | * Define shape of hierarchy based on NR_CPUS and CONFIG_RCU_FANOUT. |
33 | * In theory, it should be possible to add more levels straightforwardly. |
34 | * In practice, this has not been tested, so there is probably some |
35 | * bug somewhere. |
36 | */ |
37 | #define MAX_RCU_LVLS 4 |
38 | #define RCU_FANOUT (CONFIG_RCU_FANOUT) |
39 | #define RCU_FANOUT_SQ (RCU_FANOUT * RCU_FANOUT) |
40 | #define RCU_FANOUT_CUBE (RCU_FANOUT_SQ * RCU_FANOUT) |
41 | #define RCU_FANOUT_FOURTH (RCU_FANOUT_CUBE * RCU_FANOUT) |
42 | |
43 | #if NR_CPUS <= RCU_FANOUT |
44 | # define NUM_RCU_LVLS 1 |
45 | # define NUM_RCU_LVL_0 1 |
46 | # define NUM_RCU_LVL_1 (NR_CPUS) |
47 | # define NUM_RCU_LVL_2 0 |
48 | # define NUM_RCU_LVL_3 0 |
49 | # define NUM_RCU_LVL_4 0 |
50 | #elif NR_CPUS <= RCU_FANOUT_SQ |
51 | # define NUM_RCU_LVLS 2 |
52 | # define NUM_RCU_LVL_0 1 |
53 | # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT) |
54 | # define NUM_RCU_LVL_2 (NR_CPUS) |
55 | # define NUM_RCU_LVL_3 0 |
56 | # define NUM_RCU_LVL_4 0 |
57 | #elif NR_CPUS <= RCU_FANOUT_CUBE |
58 | # define NUM_RCU_LVLS 3 |
59 | # define NUM_RCU_LVL_0 1 |
60 | # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_SQ) |
61 | # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT) |
62 | # define NUM_RCU_LVL_3 NR_CPUS |
63 | # define NUM_RCU_LVL_4 0 |
64 | #elif NR_CPUS <= RCU_FANOUT_FOURTH |
65 | # define NUM_RCU_LVLS 4 |
66 | # define NUM_RCU_LVL_0 1 |
67 | # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_CUBE) |
68 | # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_SQ) |
69 | # define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT) |
70 | # define NUM_RCU_LVL_4 NR_CPUS |
71 | #else |
72 | # error "CONFIG_RCU_FANOUT insufficient for NR_CPUS" |
73 | #endif /* #if (NR_CPUS) <= RCU_FANOUT */ |
74 | |
75 | #define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4) |
76 | #define NUM_RCU_NODES (RCU_SUM - NR_CPUS) |
77 | |
78 | /* |
79 | * Dynticks per-CPU state. |
80 | */ |
81 | struct rcu_dynticks { |
82 | int dynticks_nesting; /* Track nesting level, sort of. */ |
83 | int dynticks; /* Even value for dynticks-idle, else odd. */ |
84 | int dynticks_nmi; /* Even value for either dynticks-idle or */ |
85 | /* not in nmi handler, else odd. So this */ |
86 | /* remains even for nmi from irq handler. */ |
87 | }; |
88 | |
89 | /* |
90 | * Definition for node within the RCU grace-period-detection hierarchy. |
91 | */ |
92 | struct rcu_node { |
93 | raw_spinlock_t lock; /* Root rcu_node's lock protects some */ |
94 | /* rcu_state fields as well as following. */ |
95 | unsigned long gpnum; /* Current grace period for this node. */ |
96 | /* This will either be equal to or one */ |
97 | /* behind the root rcu_node's gpnum. */ |
98 | unsigned long completed; /* Last GP completed for this node. */ |
99 | /* This will either be equal to or one */ |
100 | /* behind the root rcu_node's gpnum. */ |
101 | unsigned long qsmask; /* CPUs or groups that need to switch in */ |
102 | /* order for current grace period to proceed.*/ |
103 | /* In leaf rcu_node, each bit corresponds to */ |
104 | /* an rcu_data structure, otherwise, each */ |
105 | /* bit corresponds to a child rcu_node */ |
106 | /* structure. */ |
107 | unsigned long expmask; /* Groups that have ->blocked_tasks[] */ |
108 | /* elements that need to drain to allow the */ |
109 | /* current expedited grace period to */ |
110 | /* complete (only for TREE_PREEMPT_RCU). */ |
111 | unsigned long qsmaskinit; |
112 | /* Per-GP initial value for qsmask & expmask. */ |
113 | unsigned long grpmask; /* Mask to apply to parent qsmask. */ |
114 | /* Only one bit will be set in this mask. */ |
115 | int grplo; /* lowest-numbered CPU or group here. */ |
116 | int grphi; /* highest-numbered CPU or group here. */ |
117 | u8 grpnum; /* CPU/group number for next level up. */ |
118 | u8 level; /* root is at level 0. */ |
119 | struct rcu_node *parent; |
120 | struct list_head blocked_tasks[4]; |
121 | /* Tasks blocked in RCU read-side critsect. */ |
122 | /* Grace period number (->gpnum) x blocked */ |
123 | /* by tasks on the (x & 0x1) element of the */ |
124 | /* blocked_tasks[] array. */ |
125 | } ____cacheline_internodealigned_in_smp; |
126 | |
127 | /* |
128 | * Do a full breadth-first scan of the rcu_node structures for the |
129 | * specified rcu_state structure. |
130 | */ |
131 | #define rcu_for_each_node_breadth_first(rsp, rnp) \ |
132 | for ((rnp) = &(rsp)->node[0]; \ |
133 | (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++) |
134 | |
135 | /* |
136 | * Do a breadth-first scan of the non-leaf rcu_node structures for the |
137 | * specified rcu_state structure. Note that if there is a singleton |
138 | * rcu_node tree with but one rcu_node structure, this loop is a no-op. |
139 | */ |
140 | #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \ |
141 | for ((rnp) = &(rsp)->node[0]; \ |
142 | (rnp) < (rsp)->level[NUM_RCU_LVLS - 1]; (rnp)++) |
143 | |
144 | /* |
145 | * Scan the leaves of the rcu_node hierarchy for the specified rcu_state |
146 | * structure. Note that if there is a singleton rcu_node tree with but |
147 | * one rcu_node structure, this loop -will- visit the rcu_node structure. |
148 | * It is still a leaf node, even if it is also the root node. |
149 | */ |
150 | #define rcu_for_each_leaf_node(rsp, rnp) \ |
151 | for ((rnp) = (rsp)->level[NUM_RCU_LVLS - 1]; \ |
152 | (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++) |
153 | |
154 | /* Index values for nxttail array in struct rcu_data. */ |
155 | #define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */ |
156 | #define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */ |
157 | #define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */ |
158 | #define RCU_NEXT_TAIL 3 |
159 | #define RCU_NEXT_SIZE 4 |
160 | |
161 | /* Per-CPU data for read-copy update. */ |
162 | struct rcu_data { |
163 | /* 1) quiescent-state and grace-period handling : */ |
164 | unsigned long completed; /* Track rsp->completed gp number */ |
165 | /* in order to detect GP end. */ |
166 | unsigned long gpnum; /* Highest gp number that this CPU */ |
167 | /* is aware of having started. */ |
168 | unsigned long passed_quiesc_completed; |
169 | /* Value of completed at time of qs. */ |
170 | bool passed_quiesc; /* User-mode/idle loop etc. */ |
171 | bool qs_pending; /* Core waits for quiesc state. */ |
172 | bool beenonline; /* CPU online at least once. */ |
173 | bool preemptable; /* Preemptable RCU? */ |
174 | struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ |
175 | unsigned long grpmask; /* Mask to apply to leaf qsmask. */ |
176 | |
177 | /* 2) batch handling */ |
178 | /* |
179 | * If nxtlist is not NULL, it is partitioned as follows. |
180 | * Any of the partitions might be empty, in which case the |
181 | * pointer to that partition will be equal to the pointer for |
182 | * the following partition. When the list is empty, all of |
183 | * the nxttail elements point to the ->nxtlist pointer itself, |
184 | * which in that case is NULL. |
185 | * |
186 | * [nxtlist, *nxttail[RCU_DONE_TAIL]): |
187 | * Entries that batch # <= ->completed |
188 | * The grace period for these entries has completed, and |
189 | * the other grace-period-completed entries may be moved |
190 | * here temporarily in rcu_process_callbacks(). |
191 | * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]): |
192 | * Entries that batch # <= ->completed - 1: waiting for current GP |
193 | * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]): |
194 | * Entries known to have arrived before current GP ended |
195 | * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]): |
196 | * Entries that might have arrived after current GP ended |
197 | * Note that the value of *nxttail[RCU_NEXT_TAIL] will |
198 | * always be NULL, as this is the end of the list. |
199 | */ |
200 | struct rcu_head *nxtlist; |
201 | struct rcu_head **nxttail[RCU_NEXT_SIZE]; |
202 | long qlen; /* # of queued callbacks */ |
203 | long qlen_last_fqs_check; |
204 | /* qlen at last check for QS forcing */ |
205 | unsigned long n_force_qs_snap; |
206 | /* did other CPU force QS recently? */ |
207 | long blimit; /* Upper limit on a processed batch */ |
208 | |
209 | #ifdef CONFIG_NO_HZ |
210 | /* 3) dynticks interface. */ |
211 | struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ |
212 | int dynticks_snap; /* Per-GP tracking for dynticks. */ |
213 | int dynticks_nmi_snap; /* Per-GP tracking for dynticks_nmi. */ |
214 | #endif /* #ifdef CONFIG_NO_HZ */ |
215 | |
216 | /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ |
217 | #ifdef CONFIG_NO_HZ |
218 | unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ |
219 | #endif /* #ifdef CONFIG_NO_HZ */ |
220 | unsigned long offline_fqs; /* Kicked due to being offline. */ |
221 | unsigned long resched_ipi; /* Sent a resched IPI. */ |
222 | |
223 | /* 5) __rcu_pending() statistics. */ |
224 | unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */ |
225 | unsigned long n_rp_qs_pending; |
226 | unsigned long n_rp_report_qs; |
227 | unsigned long n_rp_cb_ready; |
228 | unsigned long n_rp_cpu_needs_gp; |
229 | unsigned long n_rp_gp_completed; |
230 | unsigned long n_rp_gp_started; |
231 | unsigned long n_rp_need_fqs; |
232 | unsigned long n_rp_need_nothing; |
233 | |
234 | int cpu; |
235 | }; |
236 | |
237 | /* Values for signaled field in struct rcu_state. */ |
238 | #define RCU_GP_IDLE 0 /* No grace period in progress. */ |
239 | #define RCU_GP_INIT 1 /* Grace period being initialized. */ |
240 | #define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */ |
241 | #define RCU_FORCE_QS 3 /* Need to force quiescent state. */ |
242 | #ifdef CONFIG_NO_HZ |
243 | #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK |
244 | #else /* #ifdef CONFIG_NO_HZ */ |
245 | #define RCU_SIGNAL_INIT RCU_FORCE_QS |
246 | #endif /* #else #ifdef CONFIG_NO_HZ */ |
247 | |
248 | #define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */ |
249 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR |
250 | |
251 | #ifdef CONFIG_PROVE_RCU |
252 | #define RCU_STALL_DELAY_DELTA (5 * HZ) |
253 | #else |
254 | #define RCU_STALL_DELAY_DELTA 0 |
255 | #endif |
256 | |
257 | #define RCU_SECONDS_TILL_STALL_CHECK (10 * HZ + RCU_STALL_DELAY_DELTA) |
258 | /* for rsp->jiffies_stall */ |
259 | #define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ + RCU_STALL_DELAY_DELTA) |
260 | /* for rsp->jiffies_stall */ |
261 | #define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time */ |
262 | /* to take at least one */ |
263 | /* scheduling clock irq */ |
264 | /* before ratting on them. */ |
265 | |
266 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
267 | |
268 | #define ULONG_CMP_GE(a, b) (ULONG_MAX / 2 >= (a) - (b)) |
269 | #define ULONG_CMP_LT(a, b) (ULONG_MAX / 2 < (a) - (b)) |
270 | |
271 | /* |
272 | * RCU global state, including node hierarchy. This hierarchy is |
273 | * represented in "heap" form in a dense array. The root (first level) |
274 | * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second |
275 | * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]), |
276 | * and the third level in ->node[m+1] and following (->node[m+1] referenced |
277 | * by ->level[2]). The number of levels is determined by the number of |
278 | * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy" |
279 | * consisting of a single rcu_node. |
280 | */ |
281 | struct rcu_state { |
282 | struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */ |
283 | struct rcu_node *level[NUM_RCU_LVLS]; /* Hierarchy levels. */ |
284 | u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */ |
285 | u8 levelspread[NUM_RCU_LVLS]; /* kids/node in each level. */ |
286 | struct rcu_data *rda[NR_CPUS]; /* array of rdp pointers. */ |
287 | |
288 | /* The following fields are guarded by the root rcu_node's lock. */ |
289 | |
290 | u8 signaled ____cacheline_internodealigned_in_smp; |
291 | /* Force QS state. */ |
292 | u8 fqs_active; /* force_quiescent_state() */ |
293 | /* is running. */ |
294 | u8 fqs_need_gp; /* A CPU was prevented from */ |
295 | /* starting a new grace */ |
296 | /* period because */ |
297 | /* force_quiescent_state() */ |
298 | /* was running. */ |
299 | unsigned long gpnum; /* Current gp number. */ |
300 | unsigned long completed; /* # of last completed gp. */ |
301 | |
302 | /* End of fields guarded by root rcu_node's lock. */ |
303 | |
304 | raw_spinlock_t onofflock; /* exclude on/offline and */ |
305 | /* starting new GP. Also */ |
306 | /* protects the following */ |
307 | /* orphan_cbs fields. */ |
308 | struct rcu_head *orphan_cbs_list; /* list of rcu_head structs */ |
309 | /* orphaned by all CPUs in */ |
310 | /* a given leaf rcu_node */ |
311 | /* going offline. */ |
312 | struct rcu_head **orphan_cbs_tail; /* And tail pointer. */ |
313 | long orphan_qlen; /* Number of orphaned cbs. */ |
314 | raw_spinlock_t fqslock; /* Only one task forcing */ |
315 | /* quiescent states. */ |
316 | unsigned long jiffies_force_qs; /* Time at which to invoke */ |
317 | /* force_quiescent_state(). */ |
318 | unsigned long n_force_qs; /* Number of calls to */ |
319 | /* force_quiescent_state(). */ |
320 | unsigned long n_force_qs_lh; /* ~Number of calls leaving */ |
321 | /* due to lock unavailable. */ |
322 | unsigned long n_force_qs_ngp; /* Number of calls leaving */ |
323 | /* due to no GP active. */ |
324 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR |
325 | unsigned long gp_start; /* Time at which GP started, */ |
326 | /* but in jiffies. */ |
327 | unsigned long jiffies_stall; /* Time at which to check */ |
328 | /* for CPU stalls. */ |
329 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
330 | char *name; /* Name of structure. */ |
331 | }; |
332 | |
333 | /* Return values for rcu_preempt_offline_tasks(). */ |
334 | |
335 | #define RCU_OFL_TASKS_NORM_GP 0x1 /* Tasks blocking normal */ |
336 | /* GP were moved to root. */ |
337 | #define RCU_OFL_TASKS_EXP_GP 0x2 /* Tasks blocking expedited */ |
338 | /* GP were moved to root. */ |
339 | |
340 | /* |
341 | * RCU implementation internal declarations: |
342 | */ |
343 | extern struct rcu_state rcu_sched_state; |
344 | DECLARE_PER_CPU(struct rcu_data, rcu_sched_data); |
345 | |
346 | extern struct rcu_state rcu_bh_state; |
347 | DECLARE_PER_CPU(struct rcu_data, rcu_bh_data); |
348 | |
349 | #ifdef CONFIG_TREE_PREEMPT_RCU |
350 | extern struct rcu_state rcu_preempt_state; |
351 | DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data); |
352 | #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */ |
353 | |
354 | #ifndef RCU_TREE_NONCORE |
355 | |
356 | /* Forward declarations for rcutree_plugin.h */ |
357 | static void rcu_bootup_announce(void); |
358 | long rcu_batches_completed(void); |
359 | static void rcu_preempt_note_context_switch(int cpu); |
360 | static int rcu_preempted_readers(struct rcu_node *rnp); |
361 | #ifdef CONFIG_HOTPLUG_CPU |
362 | static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, |
363 | unsigned long flags); |
364 | #endif /* #ifdef CONFIG_HOTPLUG_CPU */ |
365 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR |
366 | static void rcu_print_detail_task_stall(struct rcu_state *rsp); |
367 | static void rcu_print_task_stall(struct rcu_node *rnp); |
368 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
369 | static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); |
370 | #ifdef CONFIG_HOTPLUG_CPU |
371 | static int rcu_preempt_offline_tasks(struct rcu_state *rsp, |
372 | struct rcu_node *rnp, |
373 | struct rcu_data *rdp); |
374 | static void rcu_preempt_offline_cpu(int cpu); |
375 | #endif /* #ifdef CONFIG_HOTPLUG_CPU */ |
376 | static void rcu_preempt_check_callbacks(int cpu); |
377 | static void rcu_preempt_process_callbacks(void); |
378 | void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); |
379 | #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) |
380 | static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp); |
381 | #endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */ |
382 | static int rcu_preempt_pending(int cpu); |
383 | static int rcu_preempt_needs_cpu(int cpu); |
384 | static void __cpuinit rcu_preempt_init_percpu_data(int cpu); |
385 | static void rcu_preempt_send_cbs_to_orphanage(void); |
386 | static void __init __rcu_init_preempt(void); |
387 | static void rcu_needs_cpu_flush(void); |
388 | |
389 | #endif /* #ifndef RCU_TREE_NONCORE */ |
390 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9