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rcu: Eliminate synchronize_rcu_mult()

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Now that synchronize_rcu() waits for both RCU read-side critical
sections and preempt-disabled regions of code, the sole caller of
synchronize_rcu_mult() can be replaced by synchronize_rcu().
This patch makes this change and removes synchronize_rcu_mult().
Note that _wait_rcu_gp() still supports synchronize_rcu_mult(),
and thus might be simplified in the future to take only take
a single call_rcu() function rather than the current list of them.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney
2018-07-11 14:36:49 -07:00
committed by Paul E. McKenney
parent adbccddb4a
commit 309ba859b9
3 changed files with 3 additions and 22 deletions
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17
include/linux/rcupdate_wait.h
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@@ -31,21 +31,4 @@ do { \
#define wait_rcu_gp(...) _wait_rcu_gp(false, __VA_ARGS__) #define wait_rcu_gp(...) _wait_rcu_gp(false, __VA_ARGS__)
/**
* synchronize_rcu_mult - Wait concurrently for multiple grace periods
* @...: List of call_rcu() functions for different grace periods to wait on
*
* This macro waits concurrently for multiple types of RCU grace periods.
* For example, synchronize_rcu_mult(call_rcu, call_rcu_tasks) would wait
* on concurrent RCU and RCU-tasks grace periods. Waiting on a give SRCU
* domain requires you to write a wrapper function for that SRCU domain's
* call_srcu() function, supplying the corresponding srcu_struct.
*
* If Tiny RCU, tell _wait_rcu_gp() does not bother waiting for RCU,
* given that anywhere synchronize_rcu_mult() can be called is automatically
* a grace period.
*/
#define synchronize_rcu_mult(...) \
_wait_rcu_gp(IS_ENABLED(CONFIG_TINY_RCU), __VA_ARGS__)
#endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */ #endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */

6
kernel/rcu/update.c
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@@ -335,8 +335,7 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
/* Initialize and register callbacks for each crcu_array element. */ /* Initialize and register callbacks for each crcu_array element. */
for (i = 0; i < n; i++) { for (i = 0; i < n; i++) {
if (checktiny && if (checktiny &&
(crcu_array[i] == call_rcu || (crcu_array[i] == call_rcu)) {
crcu_array[i] == call_rcu_bh)) {
might_sleep(); might_sleep();
continue; continue;
} }
@@ -352,8 +351,7 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
/* Wait for all callbacks to be invoked. */ /* Wait for all callbacks to be invoked. */
for (i = 0; i < n; i++) { for (i = 0; i < n; i++) {
if (checktiny && if (checktiny &&
(crcu_array[i] == call_rcu || (crcu_array[i] == call_rcu))
crcu_array[i] == call_rcu_bh))
continue; continue;
for (j = 0; j < i; j++) for (j = 0; j < i; j++)
if (crcu_array[j] == crcu_array[i]) if (crcu_array[j] == crcu_array[i])

2
kernel/sched/core.c
View File

@@ -5788,7 +5788,7 @@ int sched_cpu_deactivate(unsigned int cpu)
* *
* Do sync before park smpboot threads to take care the rcu boost case. * Do sync before park smpboot threads to take care the rcu boost case.
*/ */
synchronize_rcu_mult(call_rcu, call_rcu_sched); synchronize_rcu();
if (!sched_smp_initialized) if (!sched_smp_initialized)
return 0; return 0;