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-rw-r--r--kernel/rcutree.c273
1 files changed, 177 insertions, 96 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 9c5fa9fc57ec..6b11b07cfe7f 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -47,6 +47,8 @@
47#include <linux/mutex.h> 47#include <linux/mutex.h>
48#include <linux/time.h> 48#include <linux/time.h>
49 49
50#include "rcutree.h"
51
50#ifdef CONFIG_DEBUG_LOCK_ALLOC 52#ifdef CONFIG_DEBUG_LOCK_ALLOC
51static struct lock_class_key rcu_lock_key; 53static struct lock_class_key rcu_lock_key;
52struct lockdep_map rcu_lock_map = 54struct lockdep_map rcu_lock_map =
@@ -73,30 +75,59 @@ EXPORT_SYMBOL_GPL(rcu_lock_map);
73 .n_force_qs_ngp = 0, \ 75 .n_force_qs_ngp = 0, \
74} 76}
75 77
76struct rcu_state rcu_state = RCU_STATE_INITIALIZER(rcu_state); 78struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state);
77DEFINE_PER_CPU(struct rcu_data, rcu_data); 79DEFINE_PER_CPU(struct rcu_data, rcu_sched_data);
78 80
79struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state); 81struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state);
80DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); 82DEFINE_PER_CPU(struct rcu_data, rcu_bh_data);
81 83
84extern long rcu_batches_completed_sched(void);
85static struct rcu_node *rcu_get_root(struct rcu_state *rsp);
86static void cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp,
87 struct rcu_node *rnp, unsigned long flags);
88static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags);
89#ifdef CONFIG_HOTPLUG_CPU
90static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp);
91#endif /* #ifdef CONFIG_HOTPLUG_CPU */
92static void __rcu_process_callbacks(struct rcu_state *rsp,
93 struct rcu_data *rdp);
94static void __call_rcu(struct rcu_head *head,
95 void (*func)(struct rcu_head *rcu),
96 struct rcu_state *rsp);
97static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp);
98static void __cpuinit rcu_init_percpu_data(int cpu, struct rcu_state *rsp,
99 int preemptable);
100
101#include "rcutree_plugin.h"
102
82/* 103/*
83 * Increment the quiescent state counter. 104 * Note a quiescent state. Because we do not need to know
84 * The counter is a bit degenerated: We do not need to know
85 * how many quiescent states passed, just if there was at least 105 * how many quiescent states passed, just if there was at least
86 * one since the start of the grace period. Thus just a flag. 106 * one since the start of the grace period, this just sets a flag.
87 */ 107 */
88void rcu_qsctr_inc(int cpu) 108void rcu_sched_qs(int cpu)
89{ 109{
90 struct rcu_data *rdp = &per_cpu(rcu_data, cpu); 110 unsigned long flags;
111 struct rcu_data *rdp;
112
113 local_irq_save(flags);
114 rdp = &per_cpu(rcu_sched_data, cpu);
91 rdp->passed_quiesc = 1; 115 rdp->passed_quiesc = 1;
92 rdp->passed_quiesc_completed = rdp->completed; 116 rdp->passed_quiesc_completed = rdp->completed;
117 rcu_preempt_qs(cpu);
118 local_irq_restore(flags);
93} 119}
94 120
95void rcu_bh_qsctr_inc(int cpu) 121void rcu_bh_qs(int cpu)
96{ 122{
97 struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); 123 unsigned long flags;
124 struct rcu_data *rdp;
125
126 local_irq_save(flags);
127 rdp = &per_cpu(rcu_bh_data, cpu);
98 rdp->passed_quiesc = 1; 128 rdp->passed_quiesc = 1;
99 rdp->passed_quiesc_completed = rdp->completed; 129 rdp->passed_quiesc_completed = rdp->completed;
130 local_irq_restore(flags);
100} 131}
101 132
102#ifdef CONFIG_NO_HZ 133#ifdef CONFIG_NO_HZ
@@ -111,15 +142,16 @@ static int qhimark = 10000; /* If this many pending, ignore blimit. */
111static int qlowmark = 100; /* Once only this many pending, use blimit. */ 142static int qlowmark = 100; /* Once only this many pending, use blimit. */
112 143
113static void force_quiescent_state(struct rcu_state *rsp, int relaxed); 144static void force_quiescent_state(struct rcu_state *rsp, int relaxed);
145static int rcu_pending(int cpu);
114 146
115/* 147/*
116 * Return the number of RCU batches processed thus far for debug & stats. 148 * Return the number of RCU-sched batches processed thus far for debug & stats.
117 */ 149 */
118long rcu_batches_completed(void) 150long rcu_batches_completed_sched(void)
119{ 151{
120 return rcu_state.completed; 152 return rcu_sched_state.completed;
121} 153}
122EXPORT_SYMBOL_GPL(rcu_batches_completed); 154EXPORT_SYMBOL_GPL(rcu_batches_completed_sched);
123 155
124/* 156/*
125 * Return the number of RCU BH batches processed thus far for debug & stats. 157 * Return the number of RCU BH batches processed thus far for debug & stats.
@@ -182,6 +214,10 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp)
182 return 1; 214 return 1;
183 } 215 }
184 216
217 /* If preemptable RCU, no point in sending reschedule IPI. */
218 if (rdp->preemptable)
219 return 0;
220
185 /* The CPU is online, so send it a reschedule IPI. */ 221 /* The CPU is online, so send it a reschedule IPI. */
186 if (rdp->cpu != smp_processor_id()) 222 if (rdp->cpu != smp_processor_id())
187 smp_send_reschedule(rdp->cpu); 223 smp_send_reschedule(rdp->cpu);
@@ -194,7 +230,6 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp)
194#endif /* #ifdef CONFIG_SMP */ 230#endif /* #ifdef CONFIG_SMP */
195 231
196#ifdef CONFIG_NO_HZ 232#ifdef CONFIG_NO_HZ
197static DEFINE_RATELIMIT_STATE(rcu_rs, 10 * HZ, 5);
198 233
199/** 234/**
200 * rcu_enter_nohz - inform RCU that current CPU is entering nohz 235 * rcu_enter_nohz - inform RCU that current CPU is entering nohz
@@ -214,7 +249,7 @@ void rcu_enter_nohz(void)
214 rdtp = &__get_cpu_var(rcu_dynticks); 249 rdtp = &__get_cpu_var(rcu_dynticks);
215 rdtp->dynticks++; 250 rdtp->dynticks++;
216 rdtp->dynticks_nesting--; 251 rdtp->dynticks_nesting--;
217 WARN_ON_RATELIMIT(rdtp->dynticks & 0x1, &rcu_rs); 252 WARN_ON_ONCE(rdtp->dynticks & 0x1);
218 local_irq_restore(flags); 253 local_irq_restore(flags);
219} 254}
220 255
@@ -233,7 +268,7 @@ void rcu_exit_nohz(void)
233 rdtp = &__get_cpu_var(rcu_dynticks); 268 rdtp = &__get_cpu_var(rcu_dynticks);
234 rdtp->dynticks++; 269 rdtp->dynticks++;
235 rdtp->dynticks_nesting++; 270 rdtp->dynticks_nesting++;
236 WARN_ON_RATELIMIT(!(rdtp->dynticks & 0x1), &rcu_rs); 271 WARN_ON_ONCE(!(rdtp->dynticks & 0x1));
237 local_irq_restore(flags); 272 local_irq_restore(flags);
238 smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ 273 smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
239} 274}
@@ -252,7 +287,7 @@ void rcu_nmi_enter(void)
252 if (rdtp->dynticks & 0x1) 287 if (rdtp->dynticks & 0x1)
253 return; 288 return;
254 rdtp->dynticks_nmi++; 289 rdtp->dynticks_nmi++;
255 WARN_ON_RATELIMIT(!(rdtp->dynticks_nmi & 0x1), &rcu_rs); 290 WARN_ON_ONCE(!(rdtp->dynticks_nmi & 0x1));
256 smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ 291 smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
257} 292}
258 293
@@ -271,7 +306,7 @@ void rcu_nmi_exit(void)
271 return; 306 return;
272 smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ 307 smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
273 rdtp->dynticks_nmi++; 308 rdtp->dynticks_nmi++;
274 WARN_ON_RATELIMIT(rdtp->dynticks_nmi & 0x1, &rcu_rs); 309 WARN_ON_ONCE(rdtp->dynticks_nmi & 0x1);
275} 310}
276 311
277/** 312/**
@@ -287,7 +322,7 @@ void rcu_irq_enter(void)
287 if (rdtp->dynticks_nesting++) 322 if (rdtp->dynticks_nesting++)
288 return; 323 return;
289 rdtp->dynticks++; 324 rdtp->dynticks++;
290 WARN_ON_RATELIMIT(!(rdtp->dynticks & 0x1), &rcu_rs); 325 WARN_ON_ONCE(!(rdtp->dynticks & 0x1));
291 smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */ 326 smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
292} 327}
293 328
@@ -306,10 +341,10 @@ void rcu_irq_exit(void)
306 return; 341 return;
307 smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */ 342 smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
308 rdtp->dynticks++; 343 rdtp->dynticks++;
309 WARN_ON_RATELIMIT(rdtp->dynticks & 0x1, &rcu_rs); 344 WARN_ON_ONCE(rdtp->dynticks & 0x1);
310 345
311 /* If the interrupt queued a callback, get out of dyntick mode. */ 346 /* If the interrupt queued a callback, get out of dyntick mode. */
312 if (__get_cpu_var(rcu_data).nxtlist || 347 if (__get_cpu_var(rcu_sched_data).nxtlist ||
313 __get_cpu_var(rcu_bh_data).nxtlist) 348 __get_cpu_var(rcu_bh_data).nxtlist)
314 set_need_resched(); 349 set_need_resched();
315} 350}
@@ -462,6 +497,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
462 497
463 printk(KERN_ERR "INFO: RCU detected CPU stalls:"); 498 printk(KERN_ERR "INFO: RCU detected CPU stalls:");
464 for (; rnp_cur < rnp_end; rnp_cur++) { 499 for (; rnp_cur < rnp_end; rnp_cur++) {
500 rcu_print_task_stall(rnp);
465 if (rnp_cur->qsmask == 0) 501 if (rnp_cur->qsmask == 0)
466 continue; 502 continue;
467 for (cpu = 0; cpu <= rnp_cur->grphi - rnp_cur->grplo; cpu++) 503 for (cpu = 0; cpu <= rnp_cur->grphi - rnp_cur->grplo; cpu++)
@@ -679,6 +715,19 @@ rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
679} 715}
680 716
681/* 717/*
718 * Clean up after the prior grace period and let rcu_start_gp() start up
719 * the next grace period if one is needed. Note that the caller must
720 * hold rnp->lock, as required by rcu_start_gp(), which will release it.
721 */
722static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags)
723 __releases(rnp->lock)
724{
725 rsp->completed = rsp->gpnum;
726 rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]);
727 rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */
728}
729
730/*
682 * Similar to cpu_quiet(), for which it is a helper function. Allows 731 * Similar to cpu_quiet(), for which it is a helper function. Allows
683 * a group of CPUs to be quieted at one go, though all the CPUs in the 732 * a group of CPUs to be quieted at one go, though all the CPUs in the
684 * group must be represented by the same leaf rcu_node structure. 733 * group must be represented by the same leaf rcu_node structure.
@@ -699,7 +748,7 @@ cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
699 return; 748 return;
700 } 749 }
701 rnp->qsmask &= ~mask; 750 rnp->qsmask &= ~mask;
702 if (rnp->qsmask != 0) { 751 if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) {
703 752
704 /* Other bits still set at this level, so done. */ 753 /* Other bits still set at this level, so done. */
705 spin_unlock_irqrestore(&rnp->lock, flags); 754 spin_unlock_irqrestore(&rnp->lock, flags);
@@ -719,14 +768,10 @@ cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
719 768
720 /* 769 /*
721 * Get here if we are the last CPU to pass through a quiescent 770 * Get here if we are the last CPU to pass through a quiescent
722 * state for this grace period. Clean up and let rcu_start_gp() 771 * state for this grace period. Invoke cpu_quiet_msk_finish()
723 * start up the next grace period if one is needed. Note that 772 * to clean up and start the next grace period if one is needed.
724 * we still hold rnp->lock, as required by rcu_start_gp(), which
725 * will release it.
726 */ 773 */
727 rsp->completed = rsp->gpnum; 774 cpu_quiet_msk_finish(rsp, flags); /* releases rnp->lock. */
728 rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]);
729 rcu_start_gp(rsp, flags); /* releases rnp->lock. */
730} 775}
731 776
732/* 777/*
@@ -833,11 +878,12 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
833 spin_lock(&rnp->lock); /* irqs already disabled. */ 878 spin_lock(&rnp->lock); /* irqs already disabled. */
834 rnp->qsmaskinit &= ~mask; 879 rnp->qsmaskinit &= ~mask;
835 if (rnp->qsmaskinit != 0) { 880 if (rnp->qsmaskinit != 0) {
836 spin_unlock(&rnp->lock); /* irqs already disabled. */ 881 spin_unlock(&rnp->lock); /* irqs remain disabled. */
837 break; 882 break;
838 } 883 }
884 rcu_preempt_offline_tasks(rsp, rnp);
839 mask = rnp->grpmask; 885 mask = rnp->grpmask;
840 spin_unlock(&rnp->lock); /* irqs already disabled. */ 886 spin_unlock(&rnp->lock); /* irqs remain disabled. */
841 rnp = rnp->parent; 887 rnp = rnp->parent;
842 } while (rnp != NULL); 888 } while (rnp != NULL);
843 lastcomp = rsp->completed; 889 lastcomp = rsp->completed;
@@ -850,7 +896,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
850 /* 896 /*
851 * Move callbacks from the outgoing CPU to the running CPU. 897 * Move callbacks from the outgoing CPU to the running CPU.
852 * Note that the outgoing CPU is now quiscent, so it is now 898 * Note that the outgoing CPU is now quiscent, so it is now
853 * (uncharacteristically) safe to access it rcu_data structure. 899 * (uncharacteristically) safe to access its rcu_data structure.
854 * Note also that we must carefully retain the order of the 900 * Note also that we must carefully retain the order of the
855 * outgoing CPU's callbacks in order for rcu_barrier() to work 901 * outgoing CPU's callbacks in order for rcu_barrier() to work
856 * correctly. Finally, note that we start all the callbacks 902 * correctly. Finally, note that we start all the callbacks
@@ -881,8 +927,9 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
881 */ 927 */
882static void rcu_offline_cpu(int cpu) 928static void rcu_offline_cpu(int cpu)
883{ 929{
884 __rcu_offline_cpu(cpu, &rcu_state); 930 __rcu_offline_cpu(cpu, &rcu_sched_state);
885 __rcu_offline_cpu(cpu, &rcu_bh_state); 931 __rcu_offline_cpu(cpu, &rcu_bh_state);
932 rcu_preempt_offline_cpu(cpu);
886} 933}
887 934
888#else /* #ifdef CONFIG_HOTPLUG_CPU */ 935#else /* #ifdef CONFIG_HOTPLUG_CPU */
@@ -968,6 +1015,8 @@ static void rcu_do_batch(struct rcu_data *rdp)
968 */ 1015 */
969void rcu_check_callbacks(int cpu, int user) 1016void rcu_check_callbacks(int cpu, int user)
970{ 1017{
1018 if (!rcu_pending(cpu))
1019 return; /* if nothing for RCU to do. */
971 if (user || 1020 if (user ||
972 (idle_cpu(cpu) && rcu_scheduler_active && 1021 (idle_cpu(cpu) && rcu_scheduler_active &&
973 !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { 1022 !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
@@ -976,17 +1025,16 @@ void rcu_check_callbacks(int cpu, int user)
976 * Get here if this CPU took its interrupt from user 1025 * Get here if this CPU took its interrupt from user
977 * mode or from the idle loop, and if this is not a 1026 * mode or from the idle loop, and if this is not a
978 * nested interrupt. In this case, the CPU is in 1027 * nested interrupt. In this case, the CPU is in
979 * a quiescent state, so count it. 1028 * a quiescent state, so note it.
980 * 1029 *
981 * No memory barrier is required here because both 1030 * No memory barrier is required here because both
982 * rcu_qsctr_inc() and rcu_bh_qsctr_inc() reference 1031 * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local
983 * only CPU-local variables that other CPUs neither 1032 * variables that other CPUs neither access nor modify,
984 * access nor modify, at least not while the corresponding 1033 * at least not while the corresponding CPU is online.
985 * CPU is online.
986 */ 1034 */
987 1035
988 rcu_qsctr_inc(cpu); 1036 rcu_sched_qs(cpu);
989 rcu_bh_qsctr_inc(cpu); 1037 rcu_bh_qs(cpu);
990 1038
991 } else if (!in_softirq()) { 1039 } else if (!in_softirq()) {
992 1040
@@ -994,11 +1042,12 @@ void rcu_check_callbacks(int cpu, int user)
994 * Get here if this CPU did not take its interrupt from 1042 * Get here if this CPU did not take its interrupt from
995 * softirq, in other words, if it is not interrupting 1043 * softirq, in other words, if it is not interrupting
996 * a rcu_bh read-side critical section. This is an _bh 1044 * a rcu_bh read-side critical section. This is an _bh
997 * critical section, so count it. 1045 * critical section, so note it.
998 */ 1046 */
999 1047
1000 rcu_bh_qsctr_inc(cpu); 1048 rcu_bh_qs(cpu);
1001 } 1049 }
1050 rcu_preempt_check_callbacks(cpu);
1002 raise_softirq(RCU_SOFTIRQ); 1051 raise_softirq(RCU_SOFTIRQ);
1003} 1052}
1004 1053
@@ -1137,6 +1186,8 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
1137{ 1186{
1138 unsigned long flags; 1187 unsigned long flags;
1139 1188
1189 WARN_ON_ONCE(rdp->beenonline == 0);
1190
1140 /* 1191 /*
1141 * If an RCU GP has gone long enough, go check for dyntick 1192 * If an RCU GP has gone long enough, go check for dyntick
1142 * idle CPUs and, if needed, send resched IPIs. 1193 * idle CPUs and, if needed, send resched IPIs.
@@ -1175,8 +1226,10 @@ static void rcu_process_callbacks(struct softirq_action *unused)
1175 */ 1226 */
1176 smp_mb(); /* See above block comment. */ 1227 smp_mb(); /* See above block comment. */
1177 1228
1178 __rcu_process_callbacks(&rcu_state, &__get_cpu_var(rcu_data)); 1229 __rcu_process_callbacks(&rcu_sched_state,
1230 &__get_cpu_var(rcu_sched_data));
1179 __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data)); 1231 __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data));
1232 rcu_preempt_process_callbacks();
1180 1233
1181 /* 1234 /*
1182 * Memory references from any later RCU read-side critical sections 1235 * Memory references from any later RCU read-side critical sections
@@ -1232,13 +1285,13 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
1232} 1285}
1233 1286
1234/* 1287/*
1235 * Queue an RCU callback for invocation after a grace period. 1288 * Queue an RCU-sched callback for invocation after a grace period.
1236 */ 1289 */
1237void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) 1290void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
1238{ 1291{
1239 __call_rcu(head, func, &rcu_state); 1292 __call_rcu(head, func, &rcu_sched_state);
1240} 1293}
1241EXPORT_SYMBOL_GPL(call_rcu); 1294EXPORT_SYMBOL_GPL(call_rcu_sched);
1242 1295
1243/* 1296/*
1244 * Queue an RCU for invocation after a quicker grace period. 1297 * Queue an RCU for invocation after a quicker grace period.
@@ -1310,10 +1363,11 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
1310 * by the current CPU, returning 1 if so. This function is part of the 1363 * by the current CPU, returning 1 if so. This function is part of the
1311 * RCU implementation; it is -not- an exported member of the RCU API. 1364 * RCU implementation; it is -not- an exported member of the RCU API.
1312 */ 1365 */
1313int rcu_pending(int cpu) 1366static int rcu_pending(int cpu)
1314{ 1367{
1315 return __rcu_pending(&rcu_state, &per_cpu(rcu_data, cpu)) || 1368 return __rcu_pending(&rcu_sched_state, &per_cpu(rcu_sched_data, cpu)) ||
1316 __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)); 1369 __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) ||
1370 rcu_preempt_pending(cpu);
1317} 1371}
1318 1372
1319/* 1373/*
@@ -1325,27 +1379,46 @@ int rcu_pending(int cpu)
1325int rcu_needs_cpu(int cpu) 1379int rcu_needs_cpu(int cpu)
1326{ 1380{
1327 /* RCU callbacks either ready or pending? */ 1381 /* RCU callbacks either ready or pending? */
1328 return per_cpu(rcu_data, cpu).nxtlist || 1382 return per_cpu(rcu_sched_data, cpu).nxtlist ||
1329 per_cpu(rcu_bh_data, cpu).nxtlist; 1383 per_cpu(rcu_bh_data, cpu).nxtlist ||
1384 rcu_preempt_needs_cpu(cpu);
1330} 1385}
1331 1386
1332/* 1387/*
1333 * Initialize a CPU's per-CPU RCU data. We take this "scorched earth" 1388 * Do boot-time initialization of a CPU's per-CPU RCU data.
1334 * approach so that we don't have to worry about how long the CPU has
1335 * been gone, or whether it ever was online previously. We do trust the
1336 * ->mynode field, as it is constant for a given struct rcu_data and
1337 * initialized during early boot.
1338 *
1339 * Note that only one online or offline event can be happening at a given
1340 * time. Note also that we can accept some slop in the rsp->completed
1341 * access due to the fact that this CPU cannot possibly have any RCU
1342 * callbacks in flight yet.
1343 */ 1389 */
1344static void __cpuinit 1390static void __init
1345rcu_init_percpu_data(int cpu, struct rcu_state *rsp) 1391rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
1346{ 1392{
1347 unsigned long flags; 1393 unsigned long flags;
1348 int i; 1394 int i;
1395 struct rcu_data *rdp = rsp->rda[cpu];
1396 struct rcu_node *rnp = rcu_get_root(rsp);
1397
1398 /* Set up local state, ensuring consistent view of global state. */
1399 spin_lock_irqsave(&rnp->lock, flags);
1400 rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
1401 rdp->nxtlist = NULL;
1402 for (i = 0; i < RCU_NEXT_SIZE; i++)
1403 rdp->nxttail[i] = &rdp->nxtlist;
1404 rdp->qlen = 0;
1405#ifdef CONFIG_NO_HZ
1406 rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
1407#endif /* #ifdef CONFIG_NO_HZ */
1408 rdp->cpu = cpu;
1409 spin_unlock_irqrestore(&rnp->lock, flags);
1410}
1411
1412/*
1413 * Initialize a CPU's per-CPU RCU data. Note that only one online or
1414 * offline event can be happening at a given time. Note also that we
1415 * can accept some slop in the rsp->completed access due to the fact
1416 * that this CPU cannot possibly have any RCU callbacks in flight yet.
1417 */
1418static void __cpuinit
1419rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
1420{
1421 unsigned long flags;
1349 long lastcomp; 1422 long lastcomp;
1350 unsigned long mask; 1423 unsigned long mask;
1351 struct rcu_data *rdp = rsp->rda[cpu]; 1424 struct rcu_data *rdp = rsp->rda[cpu];
@@ -1359,17 +1432,9 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
1359 rdp->passed_quiesc = 0; /* We could be racing with new GP, */ 1432 rdp->passed_quiesc = 0; /* We could be racing with new GP, */
1360 rdp->qs_pending = 1; /* so set up to respond to current GP. */ 1433 rdp->qs_pending = 1; /* so set up to respond to current GP. */
1361 rdp->beenonline = 1; /* We have now been online. */ 1434 rdp->beenonline = 1; /* We have now been online. */
1435 rdp->preemptable = preemptable;
1362 rdp->passed_quiesc_completed = lastcomp - 1; 1436 rdp->passed_quiesc_completed = lastcomp - 1;
1363 rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
1364 rdp->nxtlist = NULL;
1365 for (i = 0; i < RCU_NEXT_SIZE; i++)
1366 rdp->nxttail[i] = &rdp->nxtlist;
1367 rdp->qlen = 0;
1368 rdp->blimit = blimit; 1437 rdp->blimit = blimit;
1369#ifdef CONFIG_NO_HZ
1370 rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
1371#endif /* #ifdef CONFIG_NO_HZ */
1372 rdp->cpu = cpu;
1373 spin_unlock(&rnp->lock); /* irqs remain disabled. */ 1438 spin_unlock(&rnp->lock); /* irqs remain disabled. */
1374 1439
1375 /* 1440 /*
@@ -1410,16 +1475,16 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
1410 1475
1411static void __cpuinit rcu_online_cpu(int cpu) 1476static void __cpuinit rcu_online_cpu(int cpu)
1412{ 1477{
1413 rcu_init_percpu_data(cpu, &rcu_state); 1478 rcu_init_percpu_data(cpu, &rcu_sched_state, 0);
1414 rcu_init_percpu_data(cpu, &rcu_bh_state); 1479 rcu_init_percpu_data(cpu, &rcu_bh_state, 0);
1415 open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); 1480 rcu_preempt_init_percpu_data(cpu);
1416} 1481}
1417 1482
1418/* 1483/*
1419 * Handle CPU online/offline notifcation events. 1484 * Handle CPU online/offline notification events.
1420 */ 1485 */
1421static int __cpuinit rcu_cpu_notify(struct notifier_block *self, 1486int __cpuinit rcu_cpu_notify(struct notifier_block *self,
1422 unsigned long action, void *hcpu) 1487 unsigned long action, void *hcpu)
1423{ 1488{
1424 long cpu = (long)hcpu; 1489 long cpu = (long)hcpu;
1425 1490
@@ -1491,6 +1556,7 @@ static void __init rcu_init_one(struct rcu_state *rsp)
1491 rnp = rsp->level[i]; 1556 rnp = rsp->level[i];
1492 for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { 1557 for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) {
1493 spin_lock_init(&rnp->lock); 1558 spin_lock_init(&rnp->lock);
1559 rnp->gpnum = 0;
1494 rnp->qsmask = 0; 1560 rnp->qsmask = 0;
1495 rnp->qsmaskinit = 0; 1561 rnp->qsmaskinit = 0;
1496 rnp->grplo = j * cpustride; 1562 rnp->grplo = j * cpustride;
@@ -1508,16 +1574,20 @@ static void __init rcu_init_one(struct rcu_state *rsp)
1508 j / rsp->levelspread[i - 1]; 1574 j / rsp->levelspread[i - 1];
1509 } 1575 }
1510 rnp->level = i; 1576 rnp->level = i;
1577 INIT_LIST_HEAD(&rnp->blocked_tasks[0]);
1578 INIT_LIST_HEAD(&rnp->blocked_tasks[1]);
1511 } 1579 }
1512 } 1580 }
1513} 1581}
1514 1582
1515/* 1583/*
1516 * Helper macro for __rcu_init(). To be used nowhere else! 1584 * Helper macro for __rcu_init() and __rcu_init_preempt(). To be used
1517 * Assigns leaf node pointers into each CPU's rcu_data structure. 1585 * nowhere else! Assigns leaf node pointers into each CPU's rcu_data
1586 * structure.
1518 */ 1587 */
1519#define RCU_DATA_PTR_INIT(rsp, rcu_data) \ 1588#define RCU_INIT_FLAVOR(rsp, rcu_data) \
1520do { \ 1589do { \
1590 rcu_init_one(rsp); \
1521 rnp = (rsp)->level[NUM_RCU_LVLS - 1]; \ 1591 rnp = (rsp)->level[NUM_RCU_LVLS - 1]; \
1522 j = 0; \ 1592 j = 0; \
1523 for_each_possible_cpu(i) { \ 1593 for_each_possible_cpu(i) { \
@@ -1525,32 +1595,43 @@ do { \
1525 j++; \ 1595 j++; \
1526 per_cpu(rcu_data, i).mynode = &rnp[j]; \ 1596 per_cpu(rcu_data, i).mynode = &rnp[j]; \
1527 (rsp)->rda[i] = &per_cpu(rcu_data, i); \ 1597 (rsp)->rda[i] = &per_cpu(rcu_data, i); \
1598 rcu_boot_init_percpu_data(i, rsp); \
1528 } \ 1599 } \
1529} while (0) 1600} while (0)
1530 1601
1531static struct notifier_block __cpuinitdata rcu_nb = { 1602#ifdef CONFIG_TREE_PREEMPT_RCU
1532 .notifier_call = rcu_cpu_notify, 1603
1533}; 1604void __init __rcu_init_preempt(void)
1605{
1606 int i; /* All used by RCU_INIT_FLAVOR(). */
1607 int j;
1608 struct rcu_node *rnp;
1609
1610 RCU_INIT_FLAVOR(&rcu_preempt_state, rcu_preempt_data);
1611}
1612
1613#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
1614
1615void __init __rcu_init_preempt(void)
1616{
1617}
1618
1619#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
1534 1620
1535void __init __rcu_init(void) 1621void __init __rcu_init(void)
1536{ 1622{
1537 int i; /* All used by RCU_DATA_PTR_INIT(). */ 1623 int i; /* All used by RCU_INIT_FLAVOR(). */
1538 int j; 1624 int j;
1539 struct rcu_node *rnp; 1625 struct rcu_node *rnp;
1540 1626
1541 printk(KERN_INFO "Hierarchical RCU implementation.\n"); 1627 rcu_bootup_announce();
1542#ifdef CONFIG_RCU_CPU_STALL_DETECTOR 1628#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
1543 printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n"); 1629 printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n");
1544#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ 1630#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
1545 rcu_init_one(&rcu_state); 1631 RCU_INIT_FLAVOR(&rcu_sched_state, rcu_sched_data);
1546 RCU_DATA_PTR_INIT(&rcu_state, rcu_data); 1632 RCU_INIT_FLAVOR(&rcu_bh_state, rcu_bh_data);
1547 rcu_init_one(&rcu_bh_state); 1633 __rcu_init_preempt();
1548 RCU_DATA_PTR_INIT(&rcu_bh_state, rcu_bh_data); 1634 open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
1549
1550 for_each_online_cpu(i)
1551 rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, (void *)(long)i);
1552 /* Register notifier for non-boot CPUs */
1553 register_cpu_notifier(&rcu_nb);
1554} 1635}
1555 1636
1556module_param(blimit, int, 0); 1637module_param(blimit, int, 0);