From: "Paul E. McKenney" paulmck@kernel.org
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 --- kernel/rcu/rcu.h | 9 ++++++--- kernel/rcu/srcutiny.c | 6 ++++++ 2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index feb3ac1dc5d5..2909662c805f 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -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 diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c index 4dcbf8aa80ff..2a94f0e65606 100644 --- a/kernel/rcu/srcutiny.c +++ b/kernel/rcu/srcutiny.c @@ -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.