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rcu: Define RCU-bh update API in terms of RCU

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Now that the main RCU API knows about softirq disabling and softirq's
quiescent states, the RCU-bh update code can be dispensed with.
This commit therefore removes the RCU-bh update-side implementation and
defines RCU-bh's update-side API in terms of that of either RCU-preempt or
RCU-sched, depending on the setting of the CONFIG_PREEMPT Kconfig option.

In kernels built with CONFIG_RCU_NOCB_CPU=y this has the knock-on effect
of reducing by one the number of rcuo kthreads per CPU.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney
2018-07-01 07:40:52 -07:00
parent ba1c64c272
commit 65cfe3583b
7 changed files with 48 additions and 194 deletions
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10
include/linux/rcupdate.h
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@@ -55,11 +55,15 @@ void call_rcu(struct rcu_head *head, rcu_callback_t func);
#define call_rcu call_rcu_sched
#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
void call_rcu_bh(struct rcu_head *head, rcu_callback_t func);
void call_rcu_sched(struct rcu_head *head, rcu_callback_t func);
void synchronize_sched(void);
void rcu_barrier_tasks(void);
static inline void call_rcu_bh(struct rcu_head *head, rcu_callback_t func)
{
call_rcu(head, func);
}
#ifdef CONFIG_PREEMPT_RCU
void __rcu_read_lock(void);
@@ -104,7 +108,6 @@ static inline int rcu_preempt_depth(void)
void rcu_init(void);
extern int rcu_scheduler_active __read_mostly;
void rcu_sched_qs(void);
void rcu_bh_qs(void);
void rcu_check_callbacks(int user);
void rcu_report_dead(unsigned int cpu);
void rcutree_migrate_callbacks(int cpu);
@@ -326,8 +329,7 @@ static inline void rcu_preempt_sleep_check(void) { }
* and rcu_assign_pointer(). Some of these could be folded into their
* callers, but they are left separate in order to ease introduction of
* multiple flavors of pointers to match the multiple flavors of RCU
* (e.g., __rcu_bh, * __rcu_sched, and __srcu), should this make sense in
* the future.
* (e.g., __rcu_sched, and __srcu), should this make sense in the future.
*/
#ifdef __CHECKER__