tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2020.02.29a head: 61f7110d6b78f4c84ea5d5480185740840889af7 commit: 61f7110d6b78f4c84ea5d5480185740840889af7 [43/43] rcu-tasks: Add an RCU-tasks rude variant config: mips-rm200_defconfig (attached as .config) compiler: mipsel-linux-gcc (GCC) 5.5.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout 61f7110d6b78f4c84ea5d5480185740840889af7 # save the attached .config to linux build tree GCC_VERSION=5.5.0 make.cross ARCH=mips If you fix the issue, kindly add following tag Reported-by: kbuild test robot All error/warnings (new ones prefixed by >>): union { typeof(x) __val; char __c[1]; } __u; \ ^ kernel/rcu/tasks.h:212:7: note: in expansion of macro 'READ_ONCE' if (!READ_ONCE(t->rcu_tasks_holdout) || ^ kernel/rcu/tasks.h:212:18: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' if (!READ_ONCE(t->rcu_tasks_holdout) || ^ include/linux/compiler.h:287:22: note: in definition of macro '__READ_ONCE' __read_once_size(&(x), __u.__c, sizeof(x)); \ ^ kernel/rcu/tasks.h:212:7: note: in expansion of macro 'READ_ONCE' if (!READ_ONCE(t->rcu_tasks_holdout) || ^ kernel/rcu/tasks.h:212:18: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' if (!READ_ONCE(t->rcu_tasks_holdout) || ^ include/linux/compiler.h:287:42: note: in definition of macro '__READ_ONCE' __read_once_size(&(x), __u.__c, sizeof(x)); \ ^ kernel/rcu/tasks.h:212:7: note: in expansion of macro 'READ_ONCE' if (!READ_ONCE(t->rcu_tasks_holdout) || ^ kernel/rcu/tasks.h:212:18: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' if (!READ_ONCE(t->rcu_tasks_holdout) || ^ include/linux/compiler.h:289:30: note: in definition of macro '__READ_ONCE' __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ ^ kernel/rcu/tasks.h:212:7: note: in expansion of macro 'READ_ONCE' if (!READ_ONCE(t->rcu_tasks_holdout) || ^ kernel/rcu/tasks.h:212:18: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' if (!READ_ONCE(t->rcu_tasks_holdout) || ^ include/linux/compiler.h:289:50: note: in definition of macro '__READ_ONCE' __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ ^ kernel/rcu/tasks.h:212:7: note: in expansion of macro 'READ_ONCE' if (!READ_ONCE(t->rcu_tasks_holdout) || ^ In file included from kernel/rcu/update.c:562:0: kernel/rcu/tasks.h:213:7: error: 'struct task_struct' has no member named 'rcu_tasks_nvcsw' t->rcu_tasks_nvcsw != READ_ONCE(t->nvcsw) || ^ kernel/rcu/tasks.h:216:28: error: 'struct task_struct' has no member named 'rcu_tasks_idle_cpu' !is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) { ^ In file included from include/linux/kernel.h:11:0, from kernel/rcu/update.c:21: kernel/rcu/tasks.h:217:15: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' WRITE_ONCE(t->rcu_tasks_holdout, false); ^ include/linux/compiler.h:310:17: note: in definition of macro 'WRITE_ONCE' union { typeof(x) __val; char __c[1]; } __u = \ ^ kernel/rcu/tasks.h:217:15: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' WRITE_ONCE(t->rcu_tasks_holdout, false); ^ include/linux/compiler.h:311:30: note: in definition of macro 'WRITE_ONCE' { .__val = (__force typeof(x)) (val) }; \ ^ kernel/rcu/tasks.h:217:15: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' WRITE_ONCE(t->rcu_tasks_holdout, false); ^ include/linux/compiler.h:312:22: note: in definition of macro 'WRITE_ONCE' __write_once_size(&(x), __u.__c, sizeof(x)); \ ^ kernel/rcu/tasks.h:217:15: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' WRITE_ONCE(t->rcu_tasks_holdout, false); ^ include/linux/compiler.h:312:42: note: in definition of macro 'WRITE_ONCE' __write_once_size(&(x), __u.__c, sizeof(x)); \ ^ In file included from kernel/rcu/update.c:562:0: kernel/rcu/tasks.h:218:19: error: 'struct task_struct' has no member named 'rcu_tasks_holdout_list' list_del_init(&t->rcu_tasks_holdout_list); ^ In file included from include/linux/kernel.h:15:0, from kernel/rcu/update.c:21: kernel/rcu/tasks.h:233:5: error: 'struct task_struct' has no member named 'rcu_tasks_nvcsw' t->rcu_tasks_nvcsw, t->nvcsw, t->rcu_tasks_holdout, ^ include/linux/printk.h:300:35: note: in definition of macro 'pr_alert' printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__) ^ kernel/rcu/tasks.h:233:35: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' t->rcu_tasks_nvcsw, t->nvcsw, t->rcu_tasks_holdout, ^ include/linux/printk.h:300:35: note: in definition of macro 'pr_alert' printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__) ^ kernel/rcu/tasks.h:234:5: error: 'struct task_struct' has no member named 'rcu_tasks_idle_cpu' t->rcu_tasks_idle_cpu, cpu); ^ include/linux/printk.h:300:35: note: in definition of macro 'pr_alert' printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__) ^ In file included from kernel/rcu/update.c:562:0: kernel/rcu/tasks.h: At top level: >> kernel/rcu/tasks.h:239:38: warning: 'struct rcu_tasks' declared inside parameter list static void rcu_tasks_wait_gp(struct rcu_tasks *rtp) ^ >> kernel/rcu/tasks.h:239:38: warning: its scope is only this definition or declaration, which is probably not what you want kernel/rcu/tasks.h: In function 'rcu_tasks_wait_gp': kernel/rcu/tasks.h:271:5: error: 'struct task_struct' has no member named 'rcu_tasks_nvcsw' t->rcu_tasks_nvcsw = READ_ONCE(t->nvcsw); ^ In file included from include/linux/kernel.h:11:0, from kernel/rcu/update.c:21: kernel/rcu/tasks.h:272:16: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' WRITE_ONCE(t->rcu_tasks_holdout, true); ^ include/linux/compiler.h:310:17: note: in definition of macro 'WRITE_ONCE' union { typeof(x) __val; char __c[1]; } __u = \ ^ kernel/rcu/tasks.h:272:16: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' WRITE_ONCE(t->rcu_tasks_holdout, true); ^ include/linux/compiler.h:311:30: note: in definition of macro 'WRITE_ONCE' { .__val = (__force typeof(x)) (val) }; \ ^ kernel/rcu/tasks.h:272:16: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' WRITE_ONCE(t->rcu_tasks_holdout, true); ^ include/linux/compiler.h:312:22: note: in definition of macro 'WRITE_ONCE' __write_once_size(&(x), __u.__c, sizeof(x)); \ ^ kernel/rcu/tasks.h:272:16: error: 'struct task_struct' has no member named 'rcu_tasks_holdout' WRITE_ONCE(t->rcu_tasks_holdout, true); ^ include/linux/compiler.h:312:42: note: in definition of macro 'WRITE_ONCE' __write_once_size(&(x), __u.__c, sizeof(x)); \ ^ In file included from kernel/rcu/update.c:562:0: kernel/rcu/tasks.h:273:15: error: 'struct task_struct' has no member named 'rcu_tasks_holdout_list' list_add(&t->rcu_tasks_holdout_list, ^ kernel/rcu/tasks.h:286:20: error: 'tasks_rcu_exit_srcu' undeclared (first use in this function) synchronize_srcu(&tasks_rcu_exit_srcu); ^ kernel/rcu/tasks.h:286:20: note: each undeclared identifier is reported only once for each function it appears in In file included from include/linux/kernel.h:11:0, from kernel/rcu/update.c:21: kernel/rcu/tasks.h:313:20: error: 'rcu_task_stall_timeout' undeclared (first use in this function) rtst = READ_ONCE(rcu_task_stall_timeout); ^ include/linux/compiler.h:285:17: note: in definition of macro '__READ_ONCE' union { typeof(x) __val; char __c[1]; } __u; \ ^ kernel/rcu/tasks.h:313:10: note: in expansion of macro 'READ_ONCE' rtst = READ_ONCE(rcu_task_stall_timeout); ^ include/linux/kernel.h:987:51: error: 'struct task_struct' has no member named 'rcu_tasks_holdout_list' BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \ ^ include/linux/compiler.h:374:9: note: in definition of macro '__compiletime_assert' if (!(condition)) \ ^ include/linux/compiler.h:394:2: note: in expansion of macro '_compiletime_assert' _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) ^ include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) ^ include/linux/kernel.h:987:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \ ^ include/linux/kernel.h:987:20: note: in expansion of macro '__same_type' BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \ ^ include/linux/list.h:493:2: note: in expansion of macro 'container_of' container_of(ptr, type, member) ^ include/linux/list.h:504:2: note: in expansion of macro 'list_entry' list_entry((ptr)->next, type, member) ^ include/linux/list.h:688:13: note: in expansion of macro 'list_first_entry' for (pos = list_first_entry(head, typeof(*pos), member), \ ^ kernel/rcu/tasks.h:319:3: note: in expansion of macro 'list_for_each_entry_safe' list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts, ^ In file included from :0:0: include/linux/compiler_types.h:129:35: error: 'struct task_struct' has no member named 'rcu_tasks_holdout_list' #define __compiler_offsetof(a, b) __builtin_offsetof(a, b) ^ include/linux/stddef.h:17:32: note: in expansion of macro '__compiler_offsetof' #define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE, MEMBER) ^ include/linux/kernel.h:990:21: note: in expansion of macro 'offsetof' ((type *)(__mptr - offsetof(type, member))); }) ^ include/linux/list.h:493:2: note: in expansion of macro 'container_of' container_of(ptr, type, member) ^ include/linux/list.h:504:2: note: in expansion of macro 'list_entry' list_entry((ptr)->next, type, member) ^ include/linux/list.h:688:13: note: in expansion of macro 'list_first_entry' for (pos = list_first_entry(head, typeof(*pos), member), \ ^ kernel/rcu/tasks.h:319:3: note: in expansion of macro 'list_for_each_entry_safe' list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts, -- ^ include/linux/list.h:537:2: note: in expansion of macro 'list_entry' list_entry((pos)->member.next, typeof(*(pos)), member) ^ include/linux/list.h:691:20: note: in expansion of macro 'list_next_entry' pos = n, n = list_next_entry(n, member)) ^ kernel/rcu/tasks.h:319:3: note: in expansion of macro 'list_for_each_entry_safe' list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts, ^ include/linux/kernel.h:987:51: error: 'struct task_struct' has no member named 'rcu_tasks_holdout_list' BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \ ^ include/linux/compiler.h:374:9: note: in definition of macro '__compiletime_assert' if (!(condition)) \ ^ include/linux/compiler.h:394:2: note: in expansion of macro '_compiletime_assert' _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) ^ include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) ^ include/linux/kernel.h:987:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \ ^ include/linux/kernel.h:987:20: note: in expansion of macro '__same_type' BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \ ^ include/linux/list.h:493:2: note: in expansion of macro 'container_of' container_of(ptr, type, member) ^ include/linux/list.h:537:2: note: in expansion of macro 'list_entry' list_entry((pos)->member.next, typeof(*(pos)), member) ^ include/linux/list.h:691:20: note: in expansion of macro 'list_next_entry' pos = n, n = list_next_entry(n, member)) ^ kernel/rcu/tasks.h:319:3: note: in expansion of macro 'list_for_each_entry_safe' list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts, ^ include/linux/list.h:537:18: error: 'struct task_struct' has no member named 'rcu_tasks_holdout_list' list_entry((pos)->member.next, typeof(*(pos)), member) ^ include/linux/compiler.h:374:9: note: in definition of macro '__compiletime_assert' if (!(condition)) \ ^ include/linux/compiler.h:394:2: note: in expansion of macro '_compiletime_assert' _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) ^ include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) ^ include/linux/kernel.h:987:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \ ^ include/linux/kernel.h:988:6: note: in expansion of macro '__same_type' !__same_type(*(ptr), void), \ ^ include/linux/list.h:493:2: note: in expansion of macro 'container_of' container_of(ptr, type, member) ^ include/linux/list.h:537:2: note: in expansion of macro 'list_entry' list_entry((pos)->member.next, typeof(*(pos)), member) ^ include/linux/list.h:691:20: note: in expansion of macro 'list_next_entry' pos = n, n = list_next_entry(n, member)) ^ kernel/rcu/tasks.h:319:3: note: in expansion of macro 'list_for_each_entry_safe' list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts, ^ In file included from :0:0: include/linux/compiler_types.h:129:35: error: 'struct task_struct' has no member named 'rcu_tasks_holdout_list' #define __compiler_offsetof(a, b) __builtin_offsetof(a, b) ^ include/linux/stddef.h:17:32: note: in expansion of macro '__compiler_offsetof' #define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE, MEMBER) ^ include/linux/kernel.h:990:21: note: in expansion of macro 'offsetof' ((type *)(__mptr - offsetof(type, member))); }) ^ include/linux/list.h:493:2: note: in expansion of macro 'container_of' container_of(ptr, type, member) ^ include/linux/list.h:537:2: note: in expansion of macro 'list_entry' list_entry((pos)->member.next, typeof(*(pos)), member) ^ include/linux/list.h:691:20: note: in expansion of macro 'list_next_entry' pos = n, n = list_next_entry(n, member)) ^ kernel/rcu/tasks.h:319:3: note: in expansion of macro 'list_for_each_entry_safe' list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts, ^ In file included from kernel/rcu/update.c:562:0: kernel/rcu/tasks.h: At top level: kernel/rcu/tasks.h:347:1: warning: data definition has no type or storage class DEFINE_RCU_TASKS(rcu_tasks, rcu_tasks_wait_gp, call_rcu_tasks); ^ kernel/rcu/tasks.h:347:1: error: type defaults to 'int' in declaration of 'DEFINE_RCU_TASKS' [-Werror=implicit-int] kernel/rcu/tasks.h:347:1: warning: parameter names (without types) in function declaration kernel/rcu/tasks.h: In function 'call_rcu': >> kernel/rcu/tasks.h:369:2: error: implicit declaration of function 'call_rcu_tasks_generic' [-Werror=implicit-function-declaration] call_rcu_tasks_generic(rhp, func, &rcu_tasks); ^ >> kernel/rcu/tasks.h:369:37: error: 'rcu_tasks' undeclared (first use in this function) call_rcu_tasks_generic(rhp, func, &rcu_tasks); ^ kernel/rcu/tasks.h: In function 'synchronize_rcu': >> kernel/rcu/tasks.h:393:2: error: implicit declaration of function 'synchronize_rcu_tasks_generic' [-Werror=implicit-function-declaration] synchronize_rcu_tasks_generic(&rcu_tasks); ^ kernel/rcu/tasks.h:393:33: error: 'rcu_tasks' undeclared (first use in this function) synchronize_rcu_tasks_generic(&rcu_tasks); ^ kernel/rcu/tasks.h: In function 'rcu_spawn_tasks_kthread': >> kernel/rcu/tasks.h:412:2: error: implicit declaration of function 'rcu_spawn_tasks_kthread_generic' [-Werror=implicit-function-declaration] rcu_spawn_tasks_kthread_generic(&rcu_tasks); ^ kernel/rcu/tasks.h:412:35: error: 'rcu_tasks' undeclared (first use in this function) rcu_spawn_tasks_kthread_generic(&rcu_tasks); ^ kernel/rcu/tasks.h: At top level: kernel/rcu/tasks.h:432:43: warning: 'struct rcu_tasks' declared inside parameter list static void rcu_tasks_rude_wait_gp(struct rcu_tasks *rtp) ^ kernel/rcu/tasks.h:439:1: warning: data definition has no type or storage class DEFINE_RCU_TASKS(rcu_tasks_rude, rcu_tasks_rude_wait_gp, call_rcu_tasks_rude); ^ kernel/rcu/tasks.h:439:1: error: type defaults to 'int' in declaration of 'DEFINE_RCU_TASKS' [-Werror=implicit-int] kernel/rcu/tasks.h:439:1: warning: parameter names (without types) in function declaration kernel/rcu/tasks.h: In function 'call_rcu_tasks_rude': >> kernel/rcu/tasks.h:461:37: error: 'rcu_tasks_rude' undeclared (first use in this function) call_rcu_tasks_generic(rhp, func, &rcu_tasks_rude); ^ kernel/rcu/tasks.h: In function 'synchronize_rcu_tasks_rude': kernel/rcu/tasks.h:485:33: error: 'rcu_tasks_rude' undeclared (first use in this function) synchronize_rcu_tasks_generic(&rcu_tasks_rude); ^ kernel/rcu/tasks.h: In function 'rcu_spawn_tasks_rude_kthread': kernel/rcu/tasks.h:504:35: error: 'rcu_tasks_rude' undeclared (first use in this function) rcu_spawn_tasks_kthread_generic(&rcu_tasks_rude); ^ kernel/rcu/update.c: At top level: kernel/rcu/tasks.h:239:13: warning: 'rcu_tasks_wait_gp' defined but not used [-Wunused-function] static void rcu_tasks_wait_gp(struct rcu_tasks *rtp) ^ cc1: some warnings being treated as errors vim +/call_rcu_tasks_generic +369 kernel/rcu/tasks.h 237 238 /* Wait for one RCU-tasks grace period. */ > 239 static void rcu_tasks_wait_gp(struct rcu_tasks *rtp) 240 { 241 struct task_struct *g, *t; 242 unsigned long lastreport; 243 LIST_HEAD(rcu_tasks_holdouts); 244 int fract; 245 246 /* 247 * Wait for all pre-existing t->on_rq and t->nvcsw transitions 248 * to complete. Invoking synchronize_rcu() suffices because all 249 * these transitions occur with interrupts disabled. Without this 250 * synchronize_rcu(), a read-side critical section that started 251 * before the grace period might be incorrectly seen as having 252 * started after the grace period. 253 * 254 * This synchronize_rcu() also dispenses with the need for a 255 * memory barrier on the first store to t->rcu_tasks_holdout, 256 * as it forces the store to happen after the beginning of the 257 * grace period. 258 */ 259 synchronize_rcu(); 260 261 /* 262 * There were callbacks, so we need to wait for an RCU-tasks 263 * grace period. Start off by scanning the task list for tasks 264 * that are not already voluntarily blocked. Mark these tasks 265 * and make a list of them in rcu_tasks_holdouts. 266 */ 267 rcu_read_lock(); 268 for_each_process_thread(g, t) { 269 if (t != current && READ_ONCE(t->on_rq) && !is_idle_task(t)) { 270 get_task_struct(t); 271 t->rcu_tasks_nvcsw = READ_ONCE(t->nvcsw); 272 WRITE_ONCE(t->rcu_tasks_holdout, true); 273 list_add(&t->rcu_tasks_holdout_list, 274 &rcu_tasks_holdouts); 275 } 276 } 277 rcu_read_unlock(); 278 279 /* 280 * Wait for tasks that are in the process of exiting. This 281 * does only part of the job, ensuring that all tasks that were 282 * previously exiting reach the point where they have disabled 283 * preemption, allowing the later synchronize_rcu() to finish 284 * the job. 285 */ 286 synchronize_srcu(&tasks_rcu_exit_srcu); 287 288 /* 289 * Each pass through the following loop scans the list of holdout 290 * tasks, removing any that are no longer holdouts. When the list 291 * is empty, we are done. 292 */ 293 lastreport = jiffies; 294 295 /* Start off with HZ/10 wait and slowly back off to 1 HZ wait. */ 296 fract = 10; 297 298 for (;;) { 299 bool firstreport; 300 bool needreport; 301 int rtst; 302 struct task_struct *t1; 303 304 if (list_empty(&rcu_tasks_holdouts)) 305 break; 306 307 /* Slowly back off waiting for holdouts */ 308 schedule_timeout_interruptible(HZ/fract); 309 310 if (fract > 1) 311 fract--; 312 313 rtst = READ_ONCE(rcu_task_stall_timeout); 314 needreport = rtst > 0 && time_after(jiffies, lastreport + rtst); 315 if (needreport) 316 lastreport = jiffies; 317 firstreport = true; 318 WARN_ON(signal_pending(current)); 319 list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts, 320 rcu_tasks_holdout_list) { 321 check_holdout_task(t, needreport, &firstreport); 322 cond_resched(); 323 } 324 } 325 326 /* 327 * Because ->on_rq and ->nvcsw are not guaranteed to have a full 328 * memory barriers prior to them in the schedule() path, memory 329 * reordering on other CPUs could cause their RCU-tasks read-side 330 * critical sections to extend past the end of the grace period. 331 * However, because these ->nvcsw updates are carried out with 332 * interrupts disabled, we can use synchronize_rcu() to force the 333 * needed ordering on all such CPUs. 334 * 335 * This synchronize_rcu() also confines all ->rcu_tasks_holdout 336 * accesses to be within the grace period, avoiding the need for 337 * memory barriers for ->rcu_tasks_holdout accesses. 338 * 339 * In addition, this synchronize_rcu() waits for exiting tasks 340 * to complete their final preempt_disable() region of execution, 341 * cleaning up after the synchronize_srcu() above. 342 */ 343 synchronize_rcu(); 344 } 345 346 void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func); 347 DEFINE_RCU_TASKS(rcu_tasks, rcu_tasks_wait_gp, call_rcu_tasks); 348 349 /** 350 * call_rcu_tasks() - Queue an RCU for invocation task-based grace period 351 * @rhp: structure to be used for queueing the RCU updates. 352 * @func: actual callback function to be invoked after the grace period 353 * 354 * The callback function will be invoked some time after a full grace 355 * period elapses, in other words after all currently executing RCU 356 * read-side critical sections have completed. call_rcu_tasks() assumes 357 * that the read-side critical sections end at a voluntary context 358 * switch (not a preemption!), cond_resched_rcu_qs(), entry into idle, 359 * or transition to usermode execution. As such, there are no read-side 360 * primitives analogous to rcu_read_lock() and rcu_read_unlock() because 361 * this primitive is intended to determine that all tasks have passed 362 * through a safe state, not so much for data-strcuture synchronization. 363 * 364 * See the description of call_rcu() for more detailed information on 365 * memory ordering guarantees. 366 */ 367 void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func) 368 { > 369 call_rcu_tasks_generic(rhp, func, &rcu_tasks); 370 } 371 EXPORT_SYMBOL_GPL(call_rcu_tasks); 372 373 /** 374 * synchronize_rcu_tasks - wait until an rcu-tasks grace period has elapsed. 375 * 376 * Control will return to the caller some time after a full rcu-tasks 377 * grace period has elapsed, in other words after all currently 378 * executing rcu-tasks read-side critical sections have elapsed. These 379 * read-side critical sections are delimited by calls to schedule(), 380 * cond_resched_tasks_rcu_qs(), idle execution, userspace execution, calls 381 * to synchronize_rcu_tasks(), and (in theory, anyway) cond_resched(). 382 * 383 * This is a very specialized primitive, intended only for a few uses in 384 * tracing and other situations requiring manipulation of function 385 * preambles and profiling hooks. The synchronize_rcu_tasks() function 386 * is not (yet) intended for heavy use from multiple CPUs. 387 * 388 * See the description of synchronize_rcu() for more detailed information 389 * on memory ordering guarantees. 390 */ 391 void synchronize_rcu_tasks(void) 392 { > 393 synchronize_rcu_tasks_generic(&rcu_tasks); 394 } 395 EXPORT_SYMBOL_GPL(synchronize_rcu_tasks); 396 397 /** 398 * rcu_barrier_tasks - Wait for in-flight call_rcu_tasks() callbacks. 399 * 400 * Although the current implementation is guaranteed to wait, it is not 401 * obligated to, for example, if there are no pending callbacks. 402 */ 403 void rcu_barrier_tasks(void) 404 { 405 /* There is only one callback queue, so this is easy. ;-) */ 406 synchronize_rcu_tasks(); 407 } 408 EXPORT_SYMBOL_GPL(rcu_barrier_tasks); 409 410 static int __init rcu_spawn_tasks_kthread(void) 411 { > 412 rcu_spawn_tasks_kthread_generic(&rcu_tasks); 413 return 0; 414 } 415 core_initcall(rcu_spawn_tasks_kthread); 416 417 //////////////////////////////////////////////////////////////////////// 418 // 419 // "Rude" variant of Tasks RCU, inspired by Steve Rostedt's trick of 420 // passing an empty function to schedule_on_each_cpu(). This approach 421 // provides an asynchronous call_rcu_rude() API and batching of concurrent 422 // calls to the synchronous synchronize_rcu_rude() API. This sends IPIs 423 // far and wide and induces otherwise unnecessary context switches on all 424 // online CPUs, whether online or not. 425 426 // Empty function to allow workqueues to force a context switch. 427 static void rcu_tasks_be_rude(struct work_struct *work) 428 { 429 } 430 431 // Wait for one rude RCU-tasks grace period. 432 static void rcu_tasks_rude_wait_gp(struct rcu_tasks *rtp) 433 { 434 schedule_on_each_cpu(rcu_tasks_be_rude); 435 } 436 EXPORT_SYMBOL_GPL(rcu_tasks_rude_wait_gp); 437 438 void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func); 439 DEFINE_RCU_TASKS(rcu_tasks_rude, rcu_tasks_rude_wait_gp, call_rcu_tasks_rude); 440 441 /** 442 * call_rcu_tasks_rude() - Queue a callback rude task-based grace period 443 * @rhp: structure to be used for queueing the RCU updates. 444 * @func: actual callback function to be invoked after the grace period 445 * 446 * The callback function will be invoked some time after a full grace 447 * period elapses, in other words after all currently executing RCU 448 * read-side critical sections have completed. call_rcu_tasks_rude() 449 * assumes that the read-side critical sections end at context switch, 450 * cond_resched_rcu_qs(), or transition to usermode execution. As such, 451 * there are no read-side primitives analogous to rcu_read_lock() and 452 * rcu_read_unlock() because this primitive is intended to determine 453 * that all tasks have passed through a safe state, not so much for 454 * data-strcuture synchronization. 455 * 456 * See the description of call_rcu() for more detailed information on 457 * memory ordering guarantees. 458 */ 459 void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func) 460 { > 461 call_rcu_tasks_generic(rhp, func, &rcu_tasks_rude); 462 } 463 EXPORT_SYMBOL_GPL(call_rcu_tasks_rude); 464 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org