rcu: Make rcu_barrier() understand about missing rcuo kthreads
[linux-2.6-block.git] / kernel / rcu / tree.h
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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
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16 * along with this program; if not, you can access it online at
17 * http://www.gnu.org/licenses/gpl-2.0.html.
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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>
016a8d5b 30#include <linux/irq_work.h>
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31
32/*
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33 * Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and
34 * CONFIG_RCU_FANOUT_LEAF.
9f77da9f 35 * In theory, it should be possible to add more levels straightforwardly.
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36 * In practice, this did work well going from three levels to four.
37 * Of course, your mileage may vary.
9f77da9f 38 */
cf244dc0 39#define MAX_RCU_LVLS 4
8932a63d 40#define RCU_FANOUT_1 (CONFIG_RCU_FANOUT_LEAF)
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41#define RCU_FANOUT_2 (RCU_FANOUT_1 * CONFIG_RCU_FANOUT)
42#define RCU_FANOUT_3 (RCU_FANOUT_2 * CONFIG_RCU_FANOUT)
43#define RCU_FANOUT_4 (RCU_FANOUT_3 * CONFIG_RCU_FANOUT)
9f77da9f 44
0209f649 45#if NR_CPUS <= RCU_FANOUT_1
f885b7f2 46# define RCU_NUM_LVLS 1
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47# define NUM_RCU_LVL_0 1
48# define NUM_RCU_LVL_1 (NR_CPUS)
49# define NUM_RCU_LVL_2 0
50# define NUM_RCU_LVL_3 0
cf244dc0 51# define NUM_RCU_LVL_4 0
0209f649 52#elif NR_CPUS <= RCU_FANOUT_2
f885b7f2 53# define RCU_NUM_LVLS 2
9f77da9f 54# define NUM_RCU_LVL_0 1
0209f649 55# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
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56# define NUM_RCU_LVL_2 (NR_CPUS)
57# define NUM_RCU_LVL_3 0
cf244dc0 58# define NUM_RCU_LVL_4 0
0209f649 59#elif NR_CPUS <= RCU_FANOUT_3
f885b7f2 60# define RCU_NUM_LVLS 3
9f77da9f 61# define NUM_RCU_LVL_0 1
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62# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
63# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
64# define NUM_RCU_LVL_3 (NR_CPUS)
cf244dc0 65# define NUM_RCU_LVL_4 0
0209f649 66#elif NR_CPUS <= RCU_FANOUT_4
f885b7f2 67# define RCU_NUM_LVLS 4
cf244dc0 68# define NUM_RCU_LVL_0 1
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69# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3)
70# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
71# define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
72# define NUM_RCU_LVL_4 (NR_CPUS)
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73#else
74# error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
0209f649 75#endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */
9f77da9f 76
cf244dc0 77#define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4)
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78#define NUM_RCU_NODES (RCU_SUM - NR_CPUS)
79
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80extern int rcu_num_lvls;
81extern int rcu_num_nodes;
82
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83/*
84 * Dynticks per-CPU state.
85 */
86struct rcu_dynticks {
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87 long long dynticks_nesting; /* Track irq/process nesting level. */
88 /* Process level is worth LLONG_MAX/2. */
89 int dynticks_nmi_nesting; /* Track NMI nesting level. */
90 atomic_t dynticks; /* Even value for idle, else odd. */
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91#ifdef CONFIG_NO_HZ_FULL_SYSIDLE
92 long long dynticks_idle_nesting;
93 /* irq/process nesting level from idle. */
94 atomic_t dynticks_idle; /* Even value for idle, else odd. */
95 /* "Idle" excludes userspace execution. */
96 unsigned long dynticks_idle_jiffies;
97 /* End of last non-NMI non-idle period. */
98#endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
5955f7ee 99#ifdef CONFIG_RCU_FAST_NO_HZ
c0f4dfd4 100 bool all_lazy; /* Are all CPU's CBs lazy? */
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101 unsigned long nonlazy_posted;
102 /* # times non-lazy CBs posted to CPU. */
103 unsigned long nonlazy_posted_snap;
104 /* idle-period nonlazy_posted snapshot. */
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105 unsigned long last_accelerate;
106 /* Last jiffy CBs were accelerated. */
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107 unsigned long last_advance_all;
108 /* Last jiffy CBs were all advanced. */
9d2ad243 109 int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
5955f7ee 110#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
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111};
112
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113/* RCU's kthread states for tracing. */
114#define RCU_KTHREAD_STOPPED 0
115#define RCU_KTHREAD_RUNNING 1
116#define RCU_KTHREAD_WAITING 2
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117#define RCU_KTHREAD_OFFCPU 3
118#define RCU_KTHREAD_YIELDING 4
119#define RCU_KTHREAD_MAX 4
d71df90e 120
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121/*
122 * Definition for node within the RCU grace-period-detection hierarchy.
123 */
124struct rcu_node {
1304afb2 125 raw_spinlock_t lock; /* Root rcu_node's lock protects some */
1eba8f84 126 /* rcu_state fields as well as following. */
20133cfc 127 unsigned long gpnum; /* Current grace period for this node. */
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128 /* This will either be equal to or one */
129 /* behind the root rcu_node's gpnum. */
20133cfc 130 unsigned long completed; /* Last GP completed for this node. */
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131 /* This will either be equal to or one */
132 /* behind the root rcu_node's gpnum. */
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133 unsigned long qsmask; /* CPUs or groups that need to switch in */
134 /* order for current grace period to proceed.*/
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135 /* In leaf rcu_node, each bit corresponds to */
136 /* an rcu_data structure, otherwise, each */
137 /* bit corresponds to a child rcu_node */
138 /* structure. */
12f5f524 139 unsigned long expmask; /* Groups that have ->blkd_tasks */
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140 /* elements that need to drain to allow the */
141 /* current expedited grace period to */
142 /* complete (only for TREE_PREEMPT_RCU). */
9f77da9f 143 unsigned long qsmaskinit;
d9a3da06 144 /* Per-GP initial value for qsmask & expmask. */
9f77da9f 145 unsigned long grpmask; /* Mask to apply to parent qsmask. */
1eba8f84 146 /* Only one bit will be set in this mask. */
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147 int grplo; /* lowest-numbered CPU or group here. */
148 int grphi; /* highest-numbered CPU or group here. */
149 u8 grpnum; /* CPU/group number for next level up. */
150 u8 level; /* root is at level 0. */
151 struct rcu_node *parent;
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152 struct list_head blkd_tasks;
153 /* Tasks blocked in RCU read-side critical */
154 /* section. Tasks are placed at the head */
155 /* of this list and age towards the tail. */
156 struct list_head *gp_tasks;
157 /* Pointer to the first task blocking the */
158 /* current grace period, or NULL if there */
159 /* is no such task. */
160 struct list_head *exp_tasks;
161 /* Pointer to the first task blocking the */
162 /* current expedited grace period, or NULL */
163 /* if there is no such task. If there */
164 /* is no current expedited grace period, */
165 /* then there can cannot be any such task. */
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166#ifdef CONFIG_RCU_BOOST
167 struct list_head *boost_tasks;
168 /* Pointer to first task that needs to be */
169 /* priority boosted, or NULL if no priority */
170 /* boosting is needed for this rcu_node */
171 /* structure. If there are no tasks */
172 /* queued on this rcu_node structure that */
173 /* are blocking the current grace period, */
174 /* there can be no such task. */
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175 struct completion boost_completion;
176 /* Used to ensure that the rt_mutex used */
177 /* to carry out the boosting is fully */
178 /* released with no future boostee accesses */
179 /* before that rt_mutex is re-initialized. */
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180 struct rt_mutex boost_mtx;
181 /* Used only for the priority-boosting */
182 /* side effect, not as a lock. */
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183 unsigned long boost_time;
184 /* When to start boosting (jiffies). */
185 struct task_struct *boost_kthread_task;
186 /* kthread that takes care of priority */
187 /* boosting for this rcu_node structure. */
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188 unsigned int boost_kthread_status;
189 /* State of boost_kthread_task for tracing. */
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190 unsigned long n_tasks_boosted;
191 /* Total number of tasks boosted. */
192 unsigned long n_exp_boosts;
193 /* Number of tasks boosted for expedited GP. */
194 unsigned long n_normal_boosts;
195 /* Number of tasks boosted for normal GP. */
196 unsigned long n_balk_blkd_tasks;
197 /* Refused to boost: no blocked tasks. */
198 unsigned long n_balk_exp_gp_tasks;
199 /* Refused to boost: nothing blocking GP. */
200 unsigned long n_balk_boost_tasks;
201 /* Refused to boost: already boosting. */
202 unsigned long n_balk_notblocked;
203 /* Refused to boost: RCU RS CS still running. */
204 unsigned long n_balk_notyet;
205 /* Refused to boost: not yet time. */
206 unsigned long n_balk_nos;
207 /* Refused to boost: not sure why, though. */
208 /* This can happen due to race conditions. */
27f4d280 209#endif /* #ifdef CONFIG_RCU_BOOST */
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210#ifdef CONFIG_RCU_NOCB_CPU
211 wait_queue_head_t nocb_gp_wq[2];
212 /* Place for rcu_nocb_kthread() to wait GP. */
dae6e64d 213#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
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214 int need_future_gp[2];
215 /* Counts of upcoming no-CB GP requests. */
394f2769 216 raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp;
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217} ____cacheline_internodealigned_in_smp;
218
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219/*
220 * Do a full breadth-first scan of the rcu_node structures for the
221 * specified rcu_state structure.
222 */
223#define rcu_for_each_node_breadth_first(rsp, rnp) \
224 for ((rnp) = &(rsp)->node[0]; \
f885b7f2 225 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
a0b6c9a7 226
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227/*
228 * Do a breadth-first scan of the non-leaf rcu_node structures for the
229 * specified rcu_state structure. Note that if there is a singleton
230 * rcu_node tree with but one rcu_node structure, this loop is a no-op.
231 */
232#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
233 for ((rnp) = &(rsp)->node[0]; \
f885b7f2 234 (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)
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235
236/*
237 * Scan the leaves of the rcu_node hierarchy for the specified rcu_state
238 * structure. Note that if there is a singleton rcu_node tree with but
239 * one rcu_node structure, this loop -will- visit the rcu_node structure.
240 * It is still a leaf node, even if it is also the root node.
241 */
a0b6c9a7 242#define rcu_for_each_leaf_node(rsp, rnp) \
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243 for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
244 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
a0b6c9a7 245
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246/* Index values for nxttail array in struct rcu_data. */
247#define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */
248#define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */
249#define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */
250#define RCU_NEXT_TAIL 3
251#define RCU_NEXT_SIZE 4
252
253/* Per-CPU data for read-copy update. */
254struct rcu_data {
255 /* 1) quiescent-state and grace-period handling : */
20133cfc 256 unsigned long completed; /* Track rsp->completed gp number */
9f77da9f 257 /* in order to detect GP end. */
20133cfc 258 unsigned long gpnum; /* Highest gp number that this CPU */
9f77da9f 259 /* is aware of having started. */
e4cc1f22 260 bool passed_quiesce; /* User-mode/idle loop etc. */
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261 bool qs_pending; /* Core waits for quiesc state. */
262 bool beenonline; /* CPU online at least once. */
263 struct rcu_node *mynode; /* This CPU's leaf of hierarchy */
264 unsigned long grpmask; /* Mask to apply to leaf qsmask. */
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265#ifdef CONFIG_RCU_CPU_STALL_INFO
266 unsigned long ticks_this_gp; /* The number of scheduling-clock */
267 /* ticks this CPU has handled */
268 /* during and after the last grace */
269 /* period it is aware of. */
270#endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */
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271
272 /* 2) batch handling */
273 /*
274 * If nxtlist is not NULL, it is partitioned as follows.
275 * Any of the partitions might be empty, in which case the
276 * pointer to that partition will be equal to the pointer for
277 * the following partition. When the list is empty, all of
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278 * the nxttail elements point to the ->nxtlist pointer itself,
279 * which in that case is NULL.
9f77da9f 280 *
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281 * [nxtlist, *nxttail[RCU_DONE_TAIL]):
282 * Entries that batch # <= ->completed
283 * The grace period for these entries has completed, and
284 * the other grace-period-completed entries may be moved
285 * here temporarily in rcu_process_callbacks().
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286 * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]):
287 * Entries that batch # <= ->completed - 1: waiting for current GP
288 * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]):
289 * Entries known to have arrived before current GP ended
290 * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]):
291 * Entries that might have arrived after current GP ended
292 * Note that the value of *nxttail[RCU_NEXT_TAIL] will
293 * always be NULL, as this is the end of the list.
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294 */
295 struct rcu_head *nxtlist;
296 struct rcu_head **nxttail[RCU_NEXT_SIZE];
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297 unsigned long nxtcompleted[RCU_NEXT_SIZE];
298 /* grace periods for sublists. */
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299 long qlen_lazy; /* # of lazy queued callbacks */
300 long qlen; /* # of queued callbacks, incl lazy */
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301 long qlen_last_fqs_check;
302 /* qlen at last check for QS forcing */
269dcc1c 303 unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */
c635a4e1 304 unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */
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305 unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */
306 unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */
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307 unsigned long n_force_qs_snap;
308 /* did other CPU force QS recently? */
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309 long blimit; /* Upper limit on a processed batch */
310
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311 /* 3) dynticks interface. */
312 struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */
313 int dynticks_snap; /* Per-GP tracking for dynticks. */
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314
315 /* 4) reasons this CPU needed to be kicked by force_quiescent_state */
9f77da9f 316 unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */
9f77da9f 317 unsigned long offline_fqs; /* Kicked due to being offline. */
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318 unsigned long cond_resched_completed;
319 /* Grace period that needs help */
320 /* from cond_resched(). */
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321
322 /* 5) __rcu_pending() statistics. */
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323 unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */
324 unsigned long n_rp_qs_pending;
d21670ac 325 unsigned long n_rp_report_qs;
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326 unsigned long n_rp_cb_ready;
327 unsigned long n_rp_cpu_needs_gp;
328 unsigned long n_rp_gp_completed;
329 unsigned long n_rp_gp_started;
96d3fd0d 330 unsigned long n_rp_nocb_defer_wakeup;
20133cfc 331 unsigned long n_rp_need_nothing;
9f77da9f 332
b626c1b6 333 /* 6) _rcu_barrier() and OOM callbacks. */
06668efa 334 struct rcu_head barrier_head;
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335#ifdef CONFIG_RCU_FAST_NO_HZ
336 struct rcu_head oom_head;
337#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
06668efa 338
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339 /* 7) Callback offloading. */
340#ifdef CONFIG_RCU_NOCB_CPU
341 struct rcu_head *nocb_head; /* CBs waiting for kthread. */
342 struct rcu_head **nocb_tail;
343 atomic_long_t nocb_q_count; /* # CBs waiting for kthread */
344 atomic_long_t nocb_q_count_lazy; /* (approximate). */
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345 struct rcu_head *nocb_follower_head; /* CBs ready to invoke. */
346 struct rcu_head **nocb_follower_tail;
347 atomic_long_t nocb_follower_count; /* # CBs ready to invoke. */
348 atomic_long_t nocb_follower_count_lazy; /* (approximate). */
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349 int nocb_p_count; /* # CBs being invoked by kthread */
350 int nocb_p_count_lazy; /* (approximate). */
351 wait_queue_head_t nocb_wq; /* For nocb kthreads to sleep on. */
352 struct task_struct *nocb_kthread;
9fdd3bc9 353 int nocb_defer_wakeup; /* Defer wakeup of nocb_kthread. */
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354
355 /* The following fields are used by the leader, hence own cacheline. */
356 struct rcu_head *nocb_gp_head ____cacheline_internodealigned_in_smp;
357 /* CBs waiting for GP. */
358 struct rcu_head **nocb_gp_tail;
359 long nocb_gp_count;
360 long nocb_gp_count_lazy;
11ed7f93 361 bool nocb_leader_sleep; /* Is the nocb leader thread asleep? */
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362 struct rcu_data *nocb_next_follower;
363 /* Next follower in wakeup chain. */
364
365 /* The following fields are used by the follower, hence new cachline. */
366 struct rcu_data *nocb_leader ____cacheline_internodealigned_in_smp;
367 /* Leader CPU takes GP-end wakeups. */
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368#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
369
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370 /* 8) RCU CPU stall data. */
371#ifdef CONFIG_RCU_CPU_STALL_INFO
372 unsigned int softirq_snap; /* Snapshot of softirq activity. */
373#endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */
374
9f77da9f 375 int cpu;
d4c08f2a 376 struct rcu_state *rsp;
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377};
378
af446b70 379/* Values for fqs_state field in struct rcu_state. */
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380#define RCU_GP_IDLE 0 /* No grace period in progress. */
381#define RCU_GP_INIT 1 /* Grace period being initialized. */
382#define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */
ee47eb9f 383#define RCU_FORCE_QS 3 /* Need to force quiescent state. */
9f77da9f 384#define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK
9f77da9f 385
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386/* Values for nocb_defer_wakeup field in struct rcu_data. */
387#define RCU_NOGP_WAKE_NOT 0
388#define RCU_NOGP_WAKE 1
389#define RCU_NOGP_WAKE_FORCE 2
390
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391#define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500))
392 /* For jiffies_till_first_fqs and */
393 /* and jiffies_till_next_fqs. */
007b0924 394
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395#define RCU_JIFFIES_FQS_DIV 256 /* Very large systems need more */
396 /* delay between bouts of */
397 /* quiescent-state forcing. */
398
399#define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time to take */
400 /* at least one scheduling clock */
401 /* irq before ratting on them. */
9f77da9f 402
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403#define rcu_wait(cond) \
404do { \
405 for (;;) { \
406 set_current_state(TASK_INTERRUPTIBLE); \
407 if (cond) \
408 break; \
409 schedule(); \
410 } \
411 __set_current_state(TASK_RUNNING); \
412} while (0)
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413
414/*
415 * RCU global state, including node hierarchy. This hierarchy is
416 * represented in "heap" form in a dense array. The root (first level)
417 * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
418 * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
419 * and the third level in ->node[m+1] and following (->node[m+1] referenced
420 * by ->level[2]). The number of levels is determined by the number of
421 * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy"
422 * consisting of a single rcu_node.
423 */
424struct rcu_state {
425 struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
f885b7f2 426 struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */
9f77da9f 427 u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
f885b7f2 428 u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */
4a81e832 429 u8 flavor_mask; /* bit in flavor mask. */
394f99a9 430 struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
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431 void (*call)(struct rcu_head *head, /* call_rcu() flavor. */
432 void (*func)(struct rcu_head *head));
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433
434 /* The following fields are guarded by the root rcu_node's lock. */
435
af446b70 436 u8 fqs_state ____cacheline_internodealigned_in_smp;
9f77da9f 437 /* Force QS state. */
a46e0899 438 u8 boost; /* Subject to priority boost. */
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439 unsigned long gpnum; /* Current gp number. */
440 unsigned long completed; /* # of last completed gp. */
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441 struct task_struct *gp_kthread; /* Task for grace periods. */
442 wait_queue_head_t gp_wq; /* Where GP task waits. */
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443 short gp_flags; /* Commands for GP task. */
444 short gp_state; /* GP kthread sleep state. */
1eba8f84 445
d9a3da06 446 /* End of fields guarded by root rcu_node's lock. */
1eba8f84 447
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448 raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp;
449 /* Protect following fields. */
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450 struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */
451 /* need a grace period. */
452 struct rcu_head **orphan_nxttail; /* Tail of above. */
453 struct rcu_head *orphan_donelist; /* Orphaned callbacks that */
454 /* are ready to invoke. */
455 struct rcu_head **orphan_donetail; /* Tail of above. */
456 long qlen_lazy; /* Number of lazy callbacks. */
457 long qlen; /* Total number of callbacks. */
7b2e6011 458 /* End of fields guarded by orphan_lock. */
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459
460 struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */
461
7be7f0be 462 struct mutex barrier_mutex; /* Guards barrier fields. */
24ebbca8 463 atomic_t barrier_cpu_count; /* # CPUs waiting on. */
7db74df8 464 struct completion barrier_completion; /* Wake at barrier end. */
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465 unsigned long n_barrier_done; /* ++ at start and end of */
466 /* _rcu_barrier(). */
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467 /* End of fields guarded by barrier_mutex. */
468
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469 atomic_long_t expedited_start; /* Starting ticket. */
470 atomic_long_t expedited_done; /* Done ticket. */
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471 atomic_long_t expedited_wrap; /* # near-wrap incidents. */
472 atomic_long_t expedited_tryfail; /* # acquisition failures. */
473 atomic_long_t expedited_workdone1; /* # done by others #1. */
474 atomic_long_t expedited_workdone2; /* # done by others #2. */
475 atomic_long_t expedited_normal; /* # fallbacks to normal. */
476 atomic_long_t expedited_stoppedcpus; /* # successful stop_cpus. */
477 atomic_long_t expedited_done_tries; /* # tries to update _done. */
478 atomic_long_t expedited_done_lost; /* # times beaten to _done. */
479 atomic_long_t expedited_done_exit; /* # times exited _done loop. */
40694d66 480
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481 unsigned long jiffies_force_qs; /* Time at which to invoke */
482 /* force_quiescent_state(). */
483 unsigned long n_force_qs; /* Number of calls to */
484 /* force_quiescent_state(). */
485 unsigned long n_force_qs_lh; /* ~Number of calls leaving */
486 /* due to lock unavailable. */
487 unsigned long n_force_qs_ngp; /* Number of calls leaving */
488 /* due to no GP active. */
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489 unsigned long gp_start; /* Time at which GP started, */
490 /* but in jiffies. */
491 unsigned long jiffies_stall; /* Time at which to check */
492 /* for CPU stalls. */
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493 unsigned long jiffies_resched; /* Time at which to resched */
494 /* a reluctant CPU. */
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495 unsigned long gp_max; /* Maximum GP duration in */
496 /* jiffies. */
e66c33d5 497 const char *name; /* Name of structure. */
a4889858 498 char abbr; /* Abbreviated name. */
6ce75a23 499 struct list_head flavors; /* List of RCU flavors. */
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500};
501
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502/* Values for rcu_state structure's gp_flags field. */
503#define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */
504#define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */
505
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506/* Values for rcu_state structure's gp_flags field. */
507#define RCU_GP_WAIT_INIT 0 /* Initial state. */
508#define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */
509#define RCU_GP_WAIT_FQS 2 /* Wait for force-quiescent-state time. */
510
6ce75a23 511extern struct list_head rcu_struct_flavors;
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512
513/* Sequence through rcu_state structures for each RCU flavor. */
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514#define for_each_rcu_flavor(rsp) \
515 list_for_each_entry((rsp), &rcu_struct_flavors, flavors)
516
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517/* Return values for rcu_preempt_offline_tasks(). */
518
519#define RCU_OFL_TASKS_NORM_GP 0x1 /* Tasks blocking normal */
520 /* GP were moved to root. */
521#define RCU_OFL_TASKS_EXP_GP 0x2 /* Tasks blocking expedited */
522 /* GP were moved to root. */
523
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524/*
525 * RCU implementation internal declarations:
526 */
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527extern struct rcu_state rcu_sched_state;
528DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
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529
530extern struct rcu_state rcu_bh_state;
531DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
532
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533#ifdef CONFIG_TREE_PREEMPT_RCU
534extern struct rcu_state rcu_preempt_state;
535DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
536#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
537
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538#ifdef CONFIG_RCU_BOOST
539DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
540DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu);
541DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
542DECLARE_PER_CPU(char, rcu_cpu_has_work);
543#endif /* #ifdef CONFIG_RCU_BOOST */
544
017c4261 545#ifndef RCU_TREE_NONCORE
9f77da9f 546
9b2619af 547/* Forward declarations for rcutree_plugin.h */
dbe01350 548static void rcu_bootup_announce(void);
9b2619af 549long rcu_batches_completed(void);
cba6d0d6 550static void rcu_preempt_note_context_switch(int cpu);
27f4d280 551static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
b668c9cf 552#ifdef CONFIG_HOTPLUG_CPU
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553static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
554 unsigned long flags);
b668c9cf 555#endif /* #ifdef CONFIG_HOTPLUG_CPU */
1ed509a2 556static void rcu_print_detail_task_stall(struct rcu_state *rsp);
9bc8b558 557static int rcu_print_task_stall(struct rcu_node *rnp);
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558static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
559#ifdef CONFIG_HOTPLUG_CPU
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560static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
561 struct rcu_node *rnp,
562 struct rcu_data *rdp);
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563#endif /* #ifdef CONFIG_HOTPLUG_CPU */
564static void rcu_preempt_check_callbacks(int cpu);
9b2619af 565void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
d9a3da06 566#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU)
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567static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
568 bool wake);
d9a3da06 569#endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */
9b2619af 570static void __init __rcu_init_preempt(void);
1217ed1b 571static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
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572static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
573static void invoke_rcu_callbacks_kthread(void);
dff1672d 574static bool rcu_is_callbacks_kthread(void);
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575#ifdef CONFIG_RCU_BOOST
576static void rcu_preempt_do_callbacks(void);
49fb4c62 577static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
5d01bbd1 578 struct rcu_node *rnp);
a46e0899 579#endif /* #ifdef CONFIG_RCU_BOOST */
9386c0b7 580static void __init rcu_spawn_boost_kthreads(void);
49fb4c62 581static void rcu_prepare_kthreads(int cpu);
7cb92499 582static void rcu_cleanup_after_idle(int cpu);
aea1b35e 583static void rcu_prepare_for_idle(int cpu);
c57afe80 584static void rcu_idle_count_callbacks_posted(void);
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585static void print_cpu_stall_info_begin(void);
586static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
587static void print_cpu_stall_info_end(void);
588static void zero_cpu_stall_ticks(struct rcu_data *rdp);
589static void increment_cpu_stall_ticks(void);
d7e29933 590static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu);
dae6e64d 591static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq);
0446be48 592static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp);
dae6e64d 593static void rcu_init_one_nocb(struct rcu_node *rnp);
3fbfbf7a 594static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
96d3fd0d 595 bool lazy, unsigned long flags);
3fbfbf7a 596static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
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597 struct rcu_data *rdp,
598 unsigned long flags);
9fdd3bc9 599static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp);
96d3fd0d 600static void do_nocb_deferred_wakeup(struct rcu_data *rdp);
3fbfbf7a 601static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp);
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602static void rcu_spawn_all_nocb_kthreads(int cpu);
603static void __init rcu_spawn_nocb_kthreads(void);
604#ifdef CONFIG_RCU_NOCB_CPU
605static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp);
606#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
4a81e832 607static void __maybe_unused rcu_kick_nohz_cpu(int cpu);
34ed6246 608static bool init_nocb_callback_list(struct rcu_data *rdp);
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609static void rcu_sysidle_enter(struct rcu_dynticks *rdtp, int irq);
610static void rcu_sysidle_exit(struct rcu_dynticks *rdtp, int irq);
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611static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle,
612 unsigned long *maxj);
613static bool is_sysidle_rcu_state(struct rcu_state *rsp);
614static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle,
615 unsigned long maxj);
eb75767b 616static void rcu_bind_gp_kthread(void);
2333210b 617static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp);
a096932f 618static bool rcu_nohz_full_cpu(struct rcu_state *rsp);
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619static void rcu_dynticks_task_enter(void);
620static void rcu_dynticks_task_exit(void);
9b2619af 621
017c4261 622#endif /* #ifndef RCU_TREE_NONCORE */
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623
624#ifdef CONFIG_RCU_TRACE
625#ifdef CONFIG_RCU_NOCB_CPU
626/* Sum up queue lengths for tracing. */
627static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
628{
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629 *ql = atomic_long_read(&rdp->nocb_q_count) +
630 rdp->nocb_p_count +
631 atomic_long_read(&rdp->nocb_follower_count) +
632 rdp->nocb_p_count + rdp->nocb_gp_count;
633 *qll = atomic_long_read(&rdp->nocb_q_count_lazy) +
634 rdp->nocb_p_count_lazy +
635 atomic_long_read(&rdp->nocb_follower_count_lazy) +
636 rdp->nocb_p_count_lazy + rdp->nocb_gp_count_lazy;
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637}
638#else /* #ifdef CONFIG_RCU_NOCB_CPU */
639static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
640{
641 *ql = 0;
642 *qll = 0;
643}
644#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
645#endif /* #ifdef CONFIG_RCU_TRACE */