[rcu:dev.2020.02.29a 43/43] kernel/rcu/tasks.h:212:18: error: 'struct task_struct' has no member named 'rcu_tasks_holdout'

From: kbuild test robot
Date: Wed Mar 04 2020 - 09:43:36 EST

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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: nios2-3c120_defconfig (attached as .config)
compiler: nios2-linux-gcc (GCC) 7.5.0
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=7.5.0 make.cross ARCH=nios2

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@xxxxxxxxx>

All error/warnings (new ones prefixed by >>):

In file included from include/linux/kernel.h:11:0,
from kernel/rcu/update.c:21:
kernel/rcu/tasks.h: In function 'check_holdout_task':
>> 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:285:17: note: in definition of macro '__READ_ONCE'
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 will not be visible outside of this definition or declaration
static void rcu_tasks_wait_gp(struct rcu_tasks *rtp)
^~~~~~~~~
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); did you mean 'rcu_cpu_stall_reset'?
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 <command-line>: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,
^~~~~~~~~~~~~~~~~~~~~~~~
In file included from kernel/rcu/update.c:21:0:
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/kernel.h:986:26: note: in definition of macro 'container_of'
void *__mptr = (void *)(ptr); \
^~~
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:689:7: note: in expansion of macro 'list_next_entry'
n = list_next_entry(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 include/linux/kernel.h:11:0,
from kernel/rcu/update.c:21:
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: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:689:7: note: in expansion of macro 'list_next_entry'
n = list_next_entry(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/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:689:7: note: in expansion of macro 'list_next_entry'
n = list_next_entry(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:537:18: 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)

vim +212 kernel/rcu/tasks.h

6b80543d90000c Paul E. McKenney 2020-03-02 205
6b80543d90000c Paul E. McKenney 2020-03-02 206 /* See if tasks are still holding out, complain if so. */
6b80543d90000c Paul E. McKenney 2020-03-02 207 static void check_holdout_task(struct task_struct *t,
6b80543d90000c Paul E. McKenney 2020-03-02 208 bool needreport, bool *firstreport)
6b80543d90000c Paul E. McKenney 2020-03-02 209 {
6b80543d90000c Paul E. McKenney 2020-03-02 210 int cpu;
6b80543d90000c Paul E. McKenney 2020-03-02 211
6b80543d90000c Paul E. McKenney 2020-03-02 @212 if (!READ_ONCE(t->rcu_tasks_holdout) ||
6b80543d90000c Paul E. McKenney 2020-03-02 @213 t->rcu_tasks_nvcsw != READ_ONCE(t->nvcsw) ||
6b80543d90000c Paul E. McKenney 2020-03-02 214 !READ_ONCE(t->on_rq) ||
6b80543d90000c Paul E. McKenney 2020-03-02 215 (IS_ENABLED(CONFIG_NO_HZ_FULL) &&
6b80543d90000c Paul E. McKenney 2020-03-02 @216 !is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) {
6b80543d90000c Paul E. McKenney 2020-03-02 217 WRITE_ONCE(t->rcu_tasks_holdout, false);
6b80543d90000c Paul E. McKenney 2020-03-02 @218 list_del_init(&t->rcu_tasks_holdout_list);
6b80543d90000c Paul E. McKenney 2020-03-02 219 put_task_struct(t);
6b80543d90000c Paul E. McKenney 2020-03-02 220 return;
6b80543d90000c Paul E. McKenney 2020-03-02 221 }
6b80543d90000c Paul E. McKenney 2020-03-02 222 rcu_request_urgent_qs_task(t);
6b80543d90000c Paul E. McKenney 2020-03-02 223 if (!needreport)
6b80543d90000c Paul E. McKenney 2020-03-02 224 return;
6b80543d90000c Paul E. McKenney 2020-03-02 225 if (*firstreport) {
6b80543d90000c Paul E. McKenney 2020-03-02 226 pr_err("INFO: rcu_tasks detected stalls on tasks:\n");
6b80543d90000c Paul E. McKenney 2020-03-02 227 *firstreport = false;
6b80543d90000c Paul E. McKenney 2020-03-02 228 }
6b80543d90000c Paul E. McKenney 2020-03-02 229 cpu = task_cpu(t);
6b80543d90000c Paul E. McKenney 2020-03-02 230 pr_alert("%p: %c%c nvcsw: %lu/%lu holdout: %d idle_cpu: %d/%d\n",
6b80543d90000c Paul E. McKenney 2020-03-02 231 t, ".I"[is_idle_task(t)],
6b80543d90000c Paul E. McKenney 2020-03-02 232 "N."[cpu < 0 || !tick_nohz_full_cpu(cpu)],
6b80543d90000c Paul E. McKenney 2020-03-02 233 t->rcu_tasks_nvcsw, t->nvcsw, t->rcu_tasks_holdout,
6b80543d90000c Paul E. McKenney 2020-03-02 234 t->rcu_tasks_idle_cpu, cpu);
6b80543d90000c Paul E. McKenney 2020-03-02 235 sched_show_task(t);
6b80543d90000c Paul E. McKenney 2020-03-02 236 }
6b80543d90000c Paul E. McKenney 2020-03-02 237
61f7110d6b78f4 Paul E. McKenney 2020-03-02 238 /* Wait for one RCU-tasks grace period. */
61f7110d6b78f4 Paul E. McKenney 2020-03-02 @239 static void rcu_tasks_wait_gp(struct rcu_tasks *rtp)
6b80543d90000c Paul E. McKenney 2020-03-02 240 {
6b80543d90000c Paul E. McKenney 2020-03-02 241 struct task_struct *g, *t;
6b80543d90000c Paul E. McKenney 2020-03-02 242 unsigned long lastreport;
6b80543d90000c Paul E. McKenney 2020-03-02 243 LIST_HEAD(rcu_tasks_holdouts);
6b80543d90000c Paul E. McKenney 2020-03-02 244 int fract;
6b80543d90000c Paul E. McKenney 2020-03-02 245
6b80543d90000c Paul E. McKenney 2020-03-02 246 /*
61f7110d6b78f4 Paul E. McKenney 2020-03-02 247 * Wait for all pre-existing t->on_rq and t->nvcsw transitions
61f7110d6b78f4 Paul E. McKenney 2020-03-02 248 * to complete. Invoking synchronize_rcu() suffices because all
61f7110d6b78f4 Paul E. McKenney 2020-03-02 249 * these transitions occur with interrupts disabled. Without this
61f7110d6b78f4 Paul E. McKenney 2020-03-02 250 * synchronize_rcu(), a read-side critical section that started
61f7110d6b78f4 Paul E. McKenney 2020-03-02 251 * before the grace period might be incorrectly seen as having
61f7110d6b78f4 Paul E. McKenney 2020-03-02 252 * started after the grace period.
6b80543d90000c Paul E. McKenney 2020-03-02 253 *
61f7110d6b78f4 Paul E. McKenney 2020-03-02 254 * This synchronize_rcu() also dispenses with the need for a
61f7110d6b78f4 Paul E. McKenney 2020-03-02 255 * memory barrier on the first store to t->rcu_tasks_holdout,
61f7110d6b78f4 Paul E. McKenney 2020-03-02 256 * as it forces the store to happen after the beginning of the
61f7110d6b78f4 Paul E. McKenney 2020-03-02 257 * grace period.
6b80543d90000c Paul E. McKenney 2020-03-02 258 */
6b80543d90000c Paul E. McKenney 2020-03-02 259 synchronize_rcu();
6b80543d90000c Paul E. McKenney 2020-03-02 260
6b80543d90000c Paul E. McKenney 2020-03-02 261 /*
61f7110d6b78f4 Paul E. McKenney 2020-03-02 262 * There were callbacks, so we need to wait for an RCU-tasks
61f7110d6b78f4 Paul E. McKenney 2020-03-02 263 * grace period. Start off by scanning the task list for tasks
61f7110d6b78f4 Paul E. McKenney 2020-03-02 264 * that are not already voluntarily blocked. Mark these tasks
61f7110d6b78f4 Paul E. McKenney 2020-03-02 265 * and make a list of them in rcu_tasks_holdouts.
6b80543d90000c Paul E. McKenney 2020-03-02 266 */
6b80543d90000c Paul E. McKenney 2020-03-02 267 rcu_read_lock();
6b80543d90000c Paul E. McKenney 2020-03-02 268 for_each_process_thread(g, t) {
61f7110d6b78f4 Paul E. McKenney 2020-03-02 269 if (t != current && READ_ONCE(t->on_rq) && !is_idle_task(t)) {
6b80543d90000c Paul E. McKenney 2020-03-02 270 get_task_struct(t);
6b80543d90000c Paul E. McKenney 2020-03-02 271 t->rcu_tasks_nvcsw = READ_ONCE(t->nvcsw);
6b80543d90000c Paul E. McKenney 2020-03-02 272 WRITE_ONCE(t->rcu_tasks_holdout, true);
6b80543d90000c Paul E. McKenney 2020-03-02 273 list_add(&t->rcu_tasks_holdout_list,
6b80543d90000c Paul E. McKenney 2020-03-02 274 &rcu_tasks_holdouts);
6b80543d90000c Paul E. McKenney 2020-03-02 275 }
6b80543d90000c Paul E. McKenney 2020-03-02 276 }
6b80543d90000c Paul E. McKenney 2020-03-02 277 rcu_read_unlock();
6b80543d90000c Paul E. McKenney 2020-03-02 278
6b80543d90000c Paul E. McKenney 2020-03-02 279 /*
61f7110d6b78f4 Paul E. McKenney 2020-03-02 280 * Wait for tasks that are in the process of exiting. This
61f7110d6b78f4 Paul E. McKenney 2020-03-02 281 * does only part of the job, ensuring that all tasks that were
61f7110d6b78f4 Paul E. McKenney 2020-03-02 282 * previously exiting reach the point where they have disabled
61f7110d6b78f4 Paul E. McKenney 2020-03-02 283 * preemption, allowing the later synchronize_rcu() to finish
61f7110d6b78f4 Paul E. McKenney 2020-03-02 284 * the job.
6b80543d90000c Paul E. McKenney 2020-03-02 285 */
6b80543d90000c Paul E. McKenney 2020-03-02 @286 synchronize_srcu(&tasks_rcu_exit_srcu);
6b80543d90000c Paul E. McKenney 2020-03-02 287
6b80543d90000c Paul E. McKenney 2020-03-02 288 /*
61f7110d6b78f4 Paul E. McKenney 2020-03-02 289 * Each pass through the following loop scans the list of holdout
61f7110d6b78f4 Paul E. McKenney 2020-03-02 290 * tasks, removing any that are no longer holdouts. When the list
61f7110d6b78f4 Paul E. McKenney 2020-03-02 291 * is empty, we are done.
6b80543d90000c Paul E. McKenney 2020-03-02 292 */
6b80543d90000c Paul E. McKenney 2020-03-02 293 lastreport = jiffies;
6b80543d90000c Paul E. McKenney 2020-03-02 294
61f7110d6b78f4 Paul E. McKenney 2020-03-02 295 /* Start off with HZ/10 wait and slowly back off to 1 HZ wait. */
6b80543d90000c Paul E. McKenney 2020-03-02 296 fract = 10;
6b80543d90000c Paul E. McKenney 2020-03-02 297
6b80543d90000c Paul E. McKenney 2020-03-02 298 for (;;) {
6b80543d90000c Paul E. McKenney 2020-03-02 299 bool firstreport;
6b80543d90000c Paul E. McKenney 2020-03-02 300 bool needreport;
6b80543d90000c Paul E. McKenney 2020-03-02 301 int rtst;
6b80543d90000c Paul E. McKenney 2020-03-02 302 struct task_struct *t1;
6b80543d90000c Paul E. McKenney 2020-03-02 303
6b80543d90000c Paul E. McKenney 2020-03-02 304 if (list_empty(&rcu_tasks_holdouts))
6b80543d90000c Paul E. McKenney 2020-03-02 305 break;
6b80543d90000c Paul E. McKenney 2020-03-02 306
6b80543d90000c Paul E. McKenney 2020-03-02 307 /* Slowly back off waiting for holdouts */
6b80543d90000c Paul E. McKenney 2020-03-02 308 schedule_timeout_interruptible(HZ/fract);
6b80543d90000c Paul E. McKenney 2020-03-02 309
6b80543d90000c Paul E. McKenney 2020-03-02 310 if (fract > 1)
6b80543d90000c Paul E. McKenney 2020-03-02 311 fract--;
6b80543d90000c Paul E. McKenney 2020-03-02 312
6b80543d90000c Paul E. McKenney 2020-03-02 @313 rtst = READ_ONCE(rcu_task_stall_timeout);
61f7110d6b78f4 Paul E. McKenney 2020-03-02 314 needreport = rtst > 0 && time_after(jiffies, lastreport + rtst);
6b80543d90000c Paul E. McKenney 2020-03-02 315 if (needreport)
6b80543d90000c Paul E. McKenney 2020-03-02 316 lastreport = jiffies;
6b80543d90000c Paul E. McKenney 2020-03-02 317 firstreport = true;
6b80543d90000c Paul E. McKenney 2020-03-02 318 WARN_ON(signal_pending(current));
6b80543d90000c Paul E. McKenney 2020-03-02 @319 list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts,
6b80543d90000c Paul E. McKenney 2020-03-02 320 rcu_tasks_holdout_list) {
6b80543d90000c Paul E. McKenney 2020-03-02 321 check_holdout_task(t, needreport, &firstreport);
6b80543d90000c Paul E. McKenney 2020-03-02 322 cond_resched();
6b80543d90000c Paul E. McKenney 2020-03-02 323 }
6b80543d90000c Paul E. McKenney 2020-03-02 324 }
6b80543d90000c Paul E. McKenney 2020-03-02 325
6b80543d90000c Paul E. McKenney 2020-03-02 326 /*
61f7110d6b78f4 Paul E. McKenney 2020-03-02 327 * Because ->on_rq and ->nvcsw are not guaranteed to have a full
61f7110d6b78f4 Paul E. McKenney 2020-03-02 328 * memory barriers prior to them in the schedule() path, memory
61f7110d6b78f4 Paul E. McKenney 2020-03-02 329 * reordering on other CPUs could cause their RCU-tasks read-side
61f7110d6b78f4 Paul E. McKenney 2020-03-02 330 * critical sections to extend past the end of the grace period.
61f7110d6b78f4 Paul E. McKenney 2020-03-02 331 * However, because these ->nvcsw updates are carried out with
61f7110d6b78f4 Paul E. McKenney 2020-03-02 332 * interrupts disabled, we can use synchronize_rcu() to force the
61f7110d6b78f4 Paul E. McKenney 2020-03-02 333 * needed ordering on all such CPUs.
6b80543d90000c Paul E. McKenney 2020-03-02 334 *
61f7110d6b78f4 Paul E. McKenney 2020-03-02 335 * This synchronize_rcu() also confines all ->rcu_tasks_holdout
61f7110d6b78f4 Paul E. McKenney 2020-03-02 336 * accesses to be within the grace period, avoiding the need for
61f7110d6b78f4 Paul E. McKenney 2020-03-02 337 * memory barriers for ->rcu_tasks_holdout accesses.
6b80543d90000c Paul E. McKenney 2020-03-02 338 *
61f7110d6b78f4 Paul E. McKenney 2020-03-02 339 * In addition, this synchronize_rcu() waits for exiting tasks
61f7110d6b78f4 Paul E. McKenney 2020-03-02 340 * to complete their final preempt_disable() region of execution,
61f7110d6b78f4 Paul E. McKenney 2020-03-02 341 * cleaning up after the synchronize_srcu() above.
6b80543d90000c Paul E. McKenney 2020-03-02 342 */
6b80543d90000c Paul E. McKenney 2020-03-02 343 synchronize_rcu();
61f7110d6b78f4 Paul E. McKenney 2020-03-02 344 }
6b80543d90000c Paul E. McKenney 2020-03-02 345
61f7110d6b78f4 Paul E. McKenney 2020-03-02 346 void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func);
61f7110d6b78f4 Paul E. McKenney 2020-03-02 @347 DEFINE_RCU_TASKS(rcu_tasks, rcu_tasks_wait_gp, call_rcu_tasks);
61f7110d6b78f4 Paul E. McKenney 2020-03-02 348
61f7110d6b78f4 Paul E. McKenney 2020-03-02 349 /**
61f7110d6b78f4 Paul E. McKenney 2020-03-02 350 * call_rcu_tasks() - Queue an RCU for invocation task-based grace period
61f7110d6b78f4 Paul E. McKenney 2020-03-02 351 * @rhp: structure to be used for queueing the RCU updates.
61f7110d6b78f4 Paul E. McKenney 2020-03-02 352 * @func: actual callback function to be invoked after the grace period
61f7110d6b78f4 Paul E. McKenney 2020-03-02 353 *
61f7110d6b78f4 Paul E. McKenney 2020-03-02 354 * The callback function will be invoked some time after a full grace
61f7110d6b78f4 Paul E. McKenney 2020-03-02 355 * period elapses, in other words after all currently executing RCU
61f7110d6b78f4 Paul E. McKenney 2020-03-02 356 * read-side critical sections have completed. call_rcu_tasks() assumes
61f7110d6b78f4 Paul E. McKenney 2020-03-02 357 * that the read-side critical sections end at a voluntary context
61f7110d6b78f4 Paul E. McKenney 2020-03-02 358 * switch (not a preemption!), cond_resched_rcu_qs(), entry into idle,
61f7110d6b78f4 Paul E. McKenney 2020-03-02 359 * or transition to usermode execution. As such, there are no read-side
61f7110d6b78f4 Paul E. McKenney 2020-03-02 360 * primitives analogous to rcu_read_lock() and rcu_read_unlock() because
61f7110d6b78f4 Paul E. McKenney 2020-03-02 361 * this primitive is intended to determine that all tasks have passed
61f7110d6b78f4 Paul E. McKenney 2020-03-02 362 * through a safe state, not so much for data-strcuture synchronization.
61f7110d6b78f4 Paul E. McKenney 2020-03-02 363 *
61f7110d6b78f4 Paul E. McKenney 2020-03-02 364 * See the description of call_rcu() for more detailed information on
61f7110d6b78f4 Paul E. McKenney 2020-03-02 365 * memory ordering guarantees.
61f7110d6b78f4 Paul E. McKenney 2020-03-02 366 */
61f7110d6b78f4 Paul E. McKenney 2020-03-02 367 void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func)
61f7110d6b78f4 Paul E. McKenney 2020-03-02 368 {
61f7110d6b78f4 Paul E. McKenney 2020-03-02 @369 call_rcu_tasks_generic(rhp, func, &rcu_tasks);
6b80543d90000c Paul E. McKenney 2020-03-02 370 }
61f7110d6b78f4 Paul E. McKenney 2020-03-02 371 EXPORT_SYMBOL_GPL(call_rcu_tasks);
61f7110d6b78f4 Paul E. McKenney 2020-03-02 372
61f7110d6b78f4 Paul E. McKenney 2020-03-02 373 /**
61f7110d6b78f4 Paul E. McKenney 2020-03-02 374 * synchronize_rcu_tasks - wait until an rcu-tasks grace period has elapsed.
61f7110d6b78f4 Paul E. McKenney 2020-03-02 375 *
61f7110d6b78f4 Paul E. McKenney 2020-03-02 376 * Control will return to the caller some time after a full rcu-tasks
61f7110d6b78f4 Paul E. McKenney 2020-03-02 377 * grace period has elapsed, in other words after all currently
61f7110d6b78f4 Paul E. McKenney 2020-03-02 378 * executing rcu-tasks read-side critical sections have elapsed. These
61f7110d6b78f4 Paul E. McKenney 2020-03-02 379 * read-side critical sections are delimited by calls to schedule(),
61f7110d6b78f4 Paul E. McKenney 2020-03-02 380 * cond_resched_tasks_rcu_qs(), idle execution, userspace execution, calls
61f7110d6b78f4 Paul E. McKenney 2020-03-02 381 * to synchronize_rcu_tasks(), and (in theory, anyway) cond_resched().
61f7110d6b78f4 Paul E. McKenney 2020-03-02 382 *
61f7110d6b78f4 Paul E. McKenney 2020-03-02 383 * This is a very specialized primitive, intended only for a few uses in
61f7110d6b78f4 Paul E. McKenney 2020-03-02 384 * tracing and other situations requiring manipulation of function
61f7110d6b78f4 Paul E. McKenney 2020-03-02 385 * preambles and profiling hooks. The synchronize_rcu_tasks() function
61f7110d6b78f4 Paul E. McKenney 2020-03-02 386 * is not (yet) intended for heavy use from multiple CPUs.
61f7110d6b78f4 Paul E. McKenney 2020-03-02 387 *
61f7110d6b78f4 Paul E. McKenney 2020-03-02 388 * See the description of synchronize_rcu() for more detailed information
61f7110d6b78f4 Paul E. McKenney 2020-03-02 389 * on memory ordering guarantees.
61f7110d6b78f4 Paul E. McKenney 2020-03-02 390 */
61f7110d6b78f4 Paul E. McKenney 2020-03-02 391 void synchronize_rcu_tasks(void)
61f7110d6b78f4 Paul E. McKenney 2020-03-02 392 {
61f7110d6b78f4 Paul E. McKenney 2020-03-02 @393 synchronize_rcu_tasks_generic(&rcu_tasks);
6b80543d90000c Paul E. McKenney 2020-03-02 394 }
61f7110d6b78f4 Paul E. McKenney 2020-03-02 395 EXPORT_SYMBOL_GPL(synchronize_rcu_tasks);
61f7110d6b78f4 Paul E. McKenney 2020-03-02 396

:::::: The code at line 212 was first introduced by commit
:::::: 6b80543d90000c684123b05f075ac1433d99fa85 tasks-rcu: Move Tasks RCU to its own file

:::::: TO: Paul E. McKenney <paulmck@xxxxxxxxxx>
:::::: CC: Paul E. McKenney <paulmck@xxxxxxxxxx>

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