Blame view
kernel/rcutiny.c
9.63 KB
9b1d82fa1 rcu: "Tiny RCU", ... |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 |
/* * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * Copyright IBM Corporation, 2008 * * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> * * For detailed explanation of Read-Copy Update mechanism see - |
4ce5b9034 rcu: Do tiny clea... |
23 |
* Documentation/RCU |
9b1d82fa1 rcu: "Tiny RCU", ... |
24 |
*/ |
4ce5b9034 rcu: Do tiny clea... |
25 26 |
#include <linux/completion.h> #include <linux/interrupt.h> |
9b1d82fa1 rcu: "Tiny RCU", ... |
27 |
#include <linux/notifier.h> |
4ce5b9034 rcu: Do tiny clea... |
28 29 |
#include <linux/rcupdate.h> #include <linux/kernel.h> |
9984de1a5 kernel: Map most ... |
30 |
#include <linux/export.h> |
9b1d82fa1 rcu: "Tiny RCU", ... |
31 |
#include <linux/mutex.h> |
4ce5b9034 rcu: Do tiny clea... |
32 33 34 |
#include <linux/sched.h> #include <linux/types.h> #include <linux/init.h> |
9b1d82fa1 rcu: "Tiny RCU", ... |
35 |
#include <linux/time.h> |
4ce5b9034 rcu: Do tiny clea... |
36 |
#include <linux/cpu.h> |
268bb0ce3 sanitize <linux/p... |
37 |
#include <linux/prefetch.h> |
9b1d82fa1 rcu: "Tiny RCU", ... |
38 |
|
29c00b4a1 rcu: Add event-tr... |
39 |
#ifdef CONFIG_RCU_TRACE |
29c00b4a1 rcu: Add event-tr... |
40 |
#include <trace/events/rcu.h> |
29c00b4a1 rcu: Add event-tr... |
41 42 43 |
#endif /* #else #ifdef CONFIG_RCU_TRACE */ #include "rcu.h" |
a57eb940d rcu: Add a TINY_P... |
44 |
/* Forward declarations for rcutiny_plugin.h. */ |
24278d148 rcu: priority boo... |
45 |
struct rcu_ctrlblk; |
965a002b4 rcu: Make TINY_RC... |
46 47 48 |
static void invoke_rcu_callbacks(void); static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp); static void rcu_process_callbacks(struct softirq_action *unused); |
a57eb940d rcu: Add a TINY_P... |
49 50 51 52 53 |
static void __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), struct rcu_ctrlblk *rcp); #include "rcutiny_plugin.h" |
4145fa7fb rcu: Deconfuse dy... |
54 |
static long long rcu_dynticks_nesting = DYNTICK_TASK_NESTING; |
9b1d82fa1 rcu: "Tiny RCU", ... |
55 |
|
9b2e4f188 rcu: Track idlene... |
56 |
/* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */ |
4145fa7fb rcu: Deconfuse dy... |
57 |
static void rcu_idle_enter_common(long long oldval) |
9b2e4f188 rcu: Track idlene... |
58 59 |
{ if (rcu_dynticks_nesting) { |
4145fa7fb rcu: Deconfuse dy... |
60 61 |
RCU_TRACE(trace_rcu_dyntick("--=", oldval, rcu_dynticks_nesting)); |
9b2e4f188 rcu: Track idlene... |
62 63 |
return; } |
4145fa7fb rcu: Deconfuse dy... |
64 |
RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting)); |
99745b6a8 rcu: Make RCU use... |
65 |
if (!is_idle_task(current)) { |
0989cb467 rcu: Add more inf... |
66 |
struct task_struct *idle = idle_task(smp_processor_id()); |
9b2e4f188 rcu: Track idlene... |
67 |
RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task", |
4145fa7fb rcu: Deconfuse dy... |
68 |
oldval, rcu_dynticks_nesting)); |
9b2e4f188 rcu: Track idlene... |
69 |
ftrace_dump(DUMP_ALL); |
0989cb467 rcu: Add more inf... |
70 71 72 |
WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", current->pid, current->comm, idle->pid, idle->comm); /* must be idle task! */ |
9b2e4f188 rcu: Track idlene... |
73 74 75 76 77 78 79 80 81 82 83 |
} rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ } /* * Enter idle, which is an extended quiescent state if we have fully * entered that mode (i.e., if the new value of dynticks_nesting is zero). */ void rcu_idle_enter(void) { unsigned long flags; |
4145fa7fb rcu: Deconfuse dy... |
84 |
long long oldval; |
9b2e4f188 rcu: Track idlene... |
85 86 |
local_irq_save(flags); |
4145fa7fb rcu: Deconfuse dy... |
87 |
oldval = rcu_dynticks_nesting; |
9b2e4f188 rcu: Track idlene... |
88 |
rcu_dynticks_nesting = 0; |
4145fa7fb rcu: Deconfuse dy... |
89 |
rcu_idle_enter_common(oldval); |
9b2e4f188 rcu: Track idlene... |
90 91 92 93 94 95 96 97 98 |
local_irq_restore(flags); } /* * Exit an interrupt handler towards idle. */ void rcu_irq_exit(void) { unsigned long flags; |
4145fa7fb rcu: Deconfuse dy... |
99 |
long long oldval; |
9b2e4f188 rcu: Track idlene... |
100 101 |
local_irq_save(flags); |
4145fa7fb rcu: Deconfuse dy... |
102 |
oldval = rcu_dynticks_nesting; |
9b2e4f188 rcu: Track idlene... |
103 104 |
rcu_dynticks_nesting--; WARN_ON_ONCE(rcu_dynticks_nesting < 0); |
4145fa7fb rcu: Deconfuse dy... |
105 |
rcu_idle_enter_common(oldval); |
9b2e4f188 rcu: Track idlene... |
106 107 108 109 110 111 112 |
local_irq_restore(flags); } /* Common code for rcu_idle_exit() and rcu_irq_enter(), see kernel/rcutree.c. */ static void rcu_idle_exit_common(long long oldval) { if (oldval) { |
4145fa7fb rcu: Deconfuse dy... |
113 114 |
RCU_TRACE(trace_rcu_dyntick("++=", oldval, rcu_dynticks_nesting)); |
9b2e4f188 rcu: Track idlene... |
115 116 |
return; } |
4145fa7fb rcu: Deconfuse dy... |
117 |
RCU_TRACE(trace_rcu_dyntick("End", oldval, rcu_dynticks_nesting)); |
99745b6a8 rcu: Make RCU use... |
118 |
if (!is_idle_task(current)) { |
0989cb467 rcu: Add more inf... |
119 |
struct task_struct *idle = idle_task(smp_processor_id()); |
9b2e4f188 rcu: Track idlene... |
120 |
RCU_TRACE(trace_rcu_dyntick("Error on exit: not idle task", |
4145fa7fb rcu: Deconfuse dy... |
121 |
oldval, rcu_dynticks_nesting)); |
9b2e4f188 rcu: Track idlene... |
122 |
ftrace_dump(DUMP_ALL); |
0989cb467 rcu: Add more inf... |
123 124 125 |
WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", current->pid, current->comm, idle->pid, idle->comm); /* must be idle task! */ |
9b2e4f188 rcu: Track idlene... |
126 127 |
} } |
9b1d82fa1 rcu: "Tiny RCU", ... |
128 129 |
/* |
9b2e4f188 rcu: Track idlene... |
130 |
* Exit idle, so that we are no longer in an extended quiescent state. |
9b1d82fa1 rcu: "Tiny RCU", ... |
131 |
*/ |
9b2e4f188 rcu: Track idlene... |
132 |
void rcu_idle_exit(void) |
9b1d82fa1 rcu: "Tiny RCU", ... |
133 |
{ |
9b2e4f188 rcu: Track idlene... |
134 135 136 137 138 139 |
unsigned long flags; long long oldval; local_irq_save(flags); oldval = rcu_dynticks_nesting; WARN_ON_ONCE(oldval != 0); |
4145fa7fb rcu: Deconfuse dy... |
140 |
rcu_dynticks_nesting = DYNTICK_TASK_NESTING; |
9b2e4f188 rcu: Track idlene... |
141 142 |
rcu_idle_exit_common(oldval); local_irq_restore(flags); |
9b1d82fa1 rcu: "Tiny RCU", ... |
143 144 145 |
} /* |
9b2e4f188 rcu: Track idlene... |
146 |
* Enter an interrupt handler, moving away from idle. |
9b1d82fa1 rcu: "Tiny RCU", ... |
147 |
*/ |
9b2e4f188 rcu: Track idlene... |
148 |
void rcu_irq_enter(void) |
9b1d82fa1 rcu: "Tiny RCU", ... |
149 |
{ |
9b2e4f188 rcu: Track idlene... |
150 151 152 153 154 |
unsigned long flags; long long oldval; local_irq_save(flags); oldval = rcu_dynticks_nesting; |
9b1d82fa1 rcu: "Tiny RCU", ... |
155 |
rcu_dynticks_nesting++; |
9b2e4f188 rcu: Track idlene... |
156 157 158 |
WARN_ON_ONCE(rcu_dynticks_nesting == 0); rcu_idle_exit_common(oldval); local_irq_restore(flags); |
9b1d82fa1 rcu: "Tiny RCU", ... |
159 |
} |
9b2e4f188 rcu: Track idlene... |
160 161 162 163 164 165 166 167 168 |
#ifdef CONFIG_PROVE_RCU /* * Test whether RCU thinks that the current CPU is idle. */ int rcu_is_cpu_idle(void) { return !rcu_dynticks_nesting; } |
e6b80a3b0 rcu: Detect illeg... |
169 |
EXPORT_SYMBOL(rcu_is_cpu_idle); |
9b2e4f188 rcu: Track idlene... |
170 171 172 173 174 175 176 177 178 179 180 181 |
#endif /* #ifdef CONFIG_PROVE_RCU */ /* * Test whether the current CPU was interrupted from idle. Nested * interrupts don't count, we must be running at the first interrupt * level. */ int rcu_is_cpu_rrupt_from_idle(void) { return rcu_dynticks_nesting <= 0; } |
9b1d82fa1 rcu: "Tiny RCU", ... |
182 183 |
/* |
b554d7de8 rcu: optimize rcu... |
184 185 |
* Helper function for rcu_sched_qs() and rcu_bh_qs(). * Also irqs are disabled to avoid confusion due to interrupt handlers |
4ce5b9034 rcu: Do tiny clea... |
186 |
* invoking call_rcu(). |
9b1d82fa1 rcu: "Tiny RCU", ... |
187 188 189 |
*/ static int rcu_qsctr_help(struct rcu_ctrlblk *rcp) { |
9b1d82fa1 rcu: "Tiny RCU", ... |
190 191 192 |
if (rcp->rcucblist != NULL && rcp->donetail != rcp->curtail) { rcp->donetail = rcp->curtail; |
9b1d82fa1 rcu: "Tiny RCU", ... |
193 194 |
return 1; } |
4ce5b9034 rcu: Do tiny clea... |
195 |
|
9b1d82fa1 rcu: "Tiny RCU", ... |
196 197 198 199 200 201 202 203 204 205 |
return 0; } /* * Record an rcu quiescent state. And an rcu_bh quiescent state while we * are at it, given that any rcu quiescent state is also an rcu_bh * quiescent state. Use "+" instead of "||" to defeat short circuiting. */ void rcu_sched_qs(int cpu) { |
b554d7de8 rcu: optimize rcu... |
206 207 208 |
unsigned long flags; local_irq_save(flags); |
99652b54d rcu: rename rcuti... |
209 210 |
if (rcu_qsctr_help(&rcu_sched_ctrlblk) + rcu_qsctr_help(&rcu_bh_ctrlblk)) |
965a002b4 rcu: Make TINY_RC... |
211 |
invoke_rcu_callbacks(); |
b554d7de8 rcu: optimize rcu... |
212 |
local_irq_restore(flags); |
9b1d82fa1 rcu: "Tiny RCU", ... |
213 214 215 216 217 218 219 |
} /* * Record an rcu_bh quiescent state. */ void rcu_bh_qs(int cpu) { |
b554d7de8 rcu: optimize rcu... |
220 221 222 |
unsigned long flags; local_irq_save(flags); |
9b1d82fa1 rcu: "Tiny RCU", ... |
223 |
if (rcu_qsctr_help(&rcu_bh_ctrlblk)) |
965a002b4 rcu: Make TINY_RC... |
224 |
invoke_rcu_callbacks(); |
b554d7de8 rcu: optimize rcu... |
225 |
local_irq_restore(flags); |
9b1d82fa1 rcu: "Tiny RCU", ... |
226 227 228 229 |
} /* * Check to see if the scheduling-clock interrupt came from an extended |
9b2e4f188 rcu: Track idlene... |
230 231 232 |
* quiescent state, and, if so, tell RCU about it. This function must * be called from hardirq context. It is normally called from the * scheduling-clock interrupt. |
9b1d82fa1 rcu: "Tiny RCU", ... |
233 234 235 |
*/ void rcu_check_callbacks(int cpu, int user) { |
9b2e4f188 rcu: Track idlene... |
236 |
if (user || rcu_is_cpu_rrupt_from_idle()) |
9b1d82fa1 rcu: "Tiny RCU", ... |
237 238 239 |
rcu_sched_qs(cpu); else if (!in_softirq()) rcu_bh_qs(cpu); |
a57eb940d rcu: Add a TINY_P... |
240 |
rcu_preempt_check_callbacks(); |
9b1d82fa1 rcu: "Tiny RCU", ... |
241 242 243 |
} /* |
b2c0710c4 rcu: move TINY_RC... |
244 245 |
* Invoke the RCU callbacks on the specified rcu_ctrlkblk structure * whose grace period has elapsed. |
9b1d82fa1 rcu: "Tiny RCU", ... |
246 |
*/ |
965a002b4 rcu: Make TINY_RC... |
247 |
static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp) |
9b1d82fa1 rcu: "Tiny RCU", ... |
248 |
{ |
d4c08f2ac rcu: Add grace-pe... |
249 |
char *rn = NULL; |
9b1d82fa1 rcu: "Tiny RCU", ... |
250 |
struct rcu_head *next, *list; |
4ce5b9034 rcu: Do tiny clea... |
251 |
unsigned long flags; |
9e571a82f rcu: add tracing ... |
252 |
RCU_TRACE(int cb_count = 0); |
9b1d82fa1 rcu: "Tiny RCU", ... |
253 254 |
/* If no RCU callbacks ready to invoke, just return. */ |
29c00b4a1 rcu: Add event-tr... |
255 |
if (&rcp->rcucblist == rcp->donetail) { |
72fe701b7 rcu: Add RCU type... |
256 |
RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, -1)); |
4968c300e rcu: Augment rcu_... |
257 258 259 260 261 |
RCU_TRACE(trace_rcu_batch_end(rcp->name, 0, ACCESS_ONCE(rcp->rcucblist), need_resched(), is_idle_task(current), rcu_is_callbacks_kthread())); |
9b1d82fa1 rcu: "Tiny RCU", ... |
262 |
return; |
29c00b4a1 rcu: Add event-tr... |
263 |
} |
9b1d82fa1 rcu: "Tiny RCU", ... |
264 265 266 |
/* Move the ready-to-invoke callbacks to a local list. */ local_irq_save(flags); |
72fe701b7 rcu: Add RCU type... |
267 |
RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, -1)); |
9b1d82fa1 rcu: "Tiny RCU", ... |
268 269 270 271 272 |
list = rcp->rcucblist; rcp->rcucblist = *rcp->donetail; *rcp->donetail = NULL; if (rcp->curtail == rcp->donetail) rcp->curtail = &rcp->rcucblist; |
a57eb940d rcu: Add a TINY_P... |
273 |
rcu_preempt_remove_callbacks(rcp); |
9b1d82fa1 rcu: "Tiny RCU", ... |
274 275 276 277 |
rcp->donetail = &rcp->rcucblist; local_irq_restore(flags); /* Invoke the callbacks on the local list. */ |
d4c08f2ac rcu: Add grace-pe... |
278 |
RCU_TRACE(rn = rcp->name); |
9b1d82fa1 rcu: "Tiny RCU", ... |
279 280 281 |
while (list) { next = list->next; prefetch(next); |
551d55a94 tree/tiny rcu: Ad... |
282 |
debug_rcu_head_unqueue(list); |
b2c0710c4 rcu: move TINY_RC... |
283 |
local_bh_disable(); |
d4c08f2ac rcu: Add grace-pe... |
284 |
__rcu_reclaim(rn, list); |
b2c0710c4 rcu: move TINY_RC... |
285 |
local_bh_enable(); |
9b1d82fa1 rcu: "Tiny RCU", ... |
286 |
list = next; |
9e571a82f rcu: add tracing ... |
287 |
RCU_TRACE(cb_count++); |
9b1d82fa1 rcu: "Tiny RCU", ... |
288 |
} |
9e571a82f rcu: add tracing ... |
289 |
RCU_TRACE(rcu_trace_sub_qlen(rcp, cb_count)); |
4968c300e rcu: Augment rcu_... |
290 291 292 |
RCU_TRACE(trace_rcu_batch_end(rcp->name, cb_count, 0, need_resched(), is_idle_task(current), rcu_is_callbacks_kthread())); |
9b1d82fa1 rcu: "Tiny RCU", ... |
293 |
} |
965a002b4 rcu: Make TINY_RC... |
294 |
static void rcu_process_callbacks(struct softirq_action *unused) |
b2c0710c4 rcu: move TINY_RC... |
295 |
{ |
965a002b4 rcu: Make TINY_RC... |
296 297 298 |
__rcu_process_callbacks(&rcu_sched_ctrlblk); __rcu_process_callbacks(&rcu_bh_ctrlblk); rcu_preempt_process_callbacks(); |
b2c0710c4 rcu: move TINY_RC... |
299 300 301 |
} /* |
9b1d82fa1 rcu: "Tiny RCU", ... |
302 303 304 305 306 307 308 309 310 |
* Wait for a grace period to elapse. But it is illegal to invoke * synchronize_sched() from within an RCU read-side critical section. * Therefore, any legal call to synchronize_sched() is a quiescent * state, and so on a UP system, synchronize_sched() need do nothing. * Ditto for synchronize_rcu_bh(). (But Lai Jiangshan points out the * benefits of doing might_sleep() to reduce latency.) * * Cool, huh? (Due to Josh Triplett.) * |
da848c47b rcu: shrink rcuti... |
311 312 |
* But we want to make this a static inline later. The cond_resched() * currently makes this problematic. |
9b1d82fa1 rcu: "Tiny RCU", ... |
313 314 315 316 317 318 |
*/ void synchronize_sched(void) { cond_resched(); } EXPORT_SYMBOL_GPL(synchronize_sched); |
9b1d82fa1 rcu: "Tiny RCU", ... |
319 320 321 322 323 324 325 326 |
/* * Helper function for call_rcu() and call_rcu_bh(). */ static void __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), struct rcu_ctrlblk *rcp) { unsigned long flags; |
551d55a94 tree/tiny rcu: Ad... |
327 |
debug_rcu_head_queue(head); |
9b1d82fa1 rcu: "Tiny RCU", ... |
328 329 |
head->func = func; head->next = NULL; |
4ce5b9034 rcu: Do tiny clea... |
330 |
|
9b1d82fa1 rcu: "Tiny RCU", ... |
331 332 333 |
local_irq_save(flags); *rcp->curtail = head; rcp->curtail = &head->next; |
9e571a82f rcu: add tracing ... |
334 |
RCU_TRACE(rcp->qlen++); |
9b1d82fa1 rcu: "Tiny RCU", ... |
335 336 337 338 |
local_irq_restore(flags); } /* |
a57eb940d rcu: Add a TINY_P... |
339 |
* Post an RCU callback to be invoked after the end of an RCU-sched grace |
9b1d82fa1 rcu: "Tiny RCU", ... |
340 341 342 |
* period. But since we have but one CPU, that would be after any * quiescent state. */ |
a57eb940d rcu: Add a TINY_P... |
343 |
void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
9b1d82fa1 rcu: "Tiny RCU", ... |
344 |
{ |
99652b54d rcu: rename rcuti... |
345 |
__call_rcu(head, func, &rcu_sched_ctrlblk); |
9b1d82fa1 rcu: "Tiny RCU", ... |
346 |
} |
a57eb940d rcu: Add a TINY_P... |
347 |
EXPORT_SYMBOL_GPL(call_rcu_sched); |
9b1d82fa1 rcu: "Tiny RCU", ... |
348 349 350 351 352 |
/* * Post an RCU bottom-half callback to be invoked after any subsequent * quiescent state. */ |
4ce5b9034 rcu: Do tiny clea... |
353 |
void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) |
9b1d82fa1 rcu: "Tiny RCU", ... |
354 355 356 357 |
{ __call_rcu(head, func, &rcu_bh_ctrlblk); } EXPORT_SYMBOL_GPL(call_rcu_bh); |