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srcu: Make Tiny SRCU able to operate in preemptible kernels

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Given that SRCU allows its read-side critical sections are not just
preemptible, but also allow general blocking, there is not much
reason to restrict Tiny SRCU to non-preemptible kernels.  This commit
therefore removes Tiny SRCU dependencies on non-preemptibility, primarily
surrounding its interaction with rcutorture and early boot.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Ankur Arora <ankur.a.arora@oracle.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: <bpf@vger.kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
This commit is contained in:
Paul E. McKenney 2024-06-17 08:43:02 -07:00 committed by Boqun Feng
parent 2014c95afe
commit da2ac56237
2 changed files with 12 additions and 3 deletions
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9
kernel/rcu/rcu.h
View File

@ -611,8 +611,6 @@ void srcutorture_get_gp_data(struct srcu_struct *sp, int *flags,
static inline bool rcu_watching_zero_in_eqs(int cpu, int *vp) { return false; }
static inline unsigned long rcu_get_gp_seq(void) { return 0; }
static inline unsigned long rcu_exp_batches_completed(void) { return 0; }
static inline unsigned long
srcu_batches_completed(struct srcu_struct *sp) { return 0; }
static inline void rcu_force_quiescent_state(void) { }
static inline bool rcu_check_boost_fail(unsigned long gp_state, int *cpup) { return true; }
static inline void show_rcu_gp_kthreads(void) { }
@ -624,7 +622,6 @@ static inline void rcu_gp_slow_unregister(atomic_t *rgssp) { }
bool rcu_watching_zero_in_eqs(int cpu, int *vp);
unsigned long rcu_get_gp_seq(void);
unsigned long rcu_exp_batches_completed(void);
unsigned long srcu_batches_completed(struct srcu_struct *sp);
bool rcu_check_boost_fail(unsigned long gp_state, int *cpup);
void show_rcu_gp_kthreads(void);
int rcu_get_gp_kthreads_prio(void);
@ -636,6 +633,12 @@ void rcu_gp_slow_register(atomic_t *rgssp);
void rcu_gp_slow_unregister(atomic_t *rgssp);
#endif /* #else #ifdef CONFIG_TINY_RCU */
#ifdef CONFIG_TINY_SRCU
static inline unsigned long srcu_batches_completed(struct srcu_struct *sp) { return 0; }
#else // #ifdef CONFIG_TINY_SRCU
unsigned long srcu_batches_completed(struct srcu_struct *sp);
#endif // #else // #ifdef CONFIG_TINY_SRCU
#ifdef CONFIG_RCU_NOCB_CPU
void rcu_bind_current_to_nocb(void);
#else

6
kernel/rcu/srcutiny.c
View File

@ -20,7 +20,11 @@
#include "rcu_segcblist.h"
#include "rcu.h"
#ifndef CONFIG_TREE_RCU
int rcu_scheduler_active __read_mostly;
#else // #ifndef CONFIG_TREE_RCU
extern int rcu_scheduler_active;
#endif // #else // #ifndef CONFIG_TREE_RCU
static LIST_HEAD(srcu_boot_list);
static bool srcu_init_done;
@ -282,11 +286,13 @@ bool poll_state_synchronize_srcu(struct srcu_struct *ssp, unsigned long cookie)
}
EXPORT_SYMBOL_GPL(poll_state_synchronize_srcu);
#ifndef CONFIG_TREE_RCU
/* Lockdep diagnostics. */
void __init rcu_scheduler_starting(void)
{
rcu_scheduler_active = RCU_SCHEDULER_RUNNING;
}
#endif // #ifndef CONFIG_TREE_RCU
/*
* Queue work for srcu_struct structures with early boot callbacks.