Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 2/5] srcu: Initialize SRCU after timers | Date | Fri, 9 Apr 2021 00:38:59 +0200 |
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Once srcu_init() is called, the SRCU core is free to queue delayed workqueues, which rely on timers. However init_timers() is called several steps after rcu_init(). Any call_srcu() in-between would finish its course inside a dangerously uninitialized timer core.
Make sure we stay in early SRCU mode until everything is well settled.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Uladzislau Rezki <urezki@gmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Neeraj Upadhyay <neeraju@codeaurora.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Joel Fernandes <joel@joelfernandes.org> --- include/linux/srcu.h | 6 ++++++ init/main.c | 2 ++ kernel/rcu/rcu.h | 6 ------ kernel/rcu/srcutree.c | 5 +++++ kernel/rcu/tiny.c | 1 - kernel/rcu/tree.c | 1 - 6 files changed, 13 insertions(+), 8 deletions(-)
diff --git a/include/linux/srcu.h b/include/linux/srcu.h index a0895bbf71ce..e6011a9975af 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -64,6 +64,12 @@ unsigned long get_state_synchronize_srcu(struct srcu_struct *ssp); unsigned long start_poll_synchronize_srcu(struct srcu_struct *ssp); bool poll_state_synchronize_srcu(struct srcu_struct *ssp, unsigned long cookie); +#ifdef CONFIG_SRCU +void srcu_init(void); +#else /* #ifdef CONFIG_SRCU */ +static inline void srcu_init(void) { } +#endif /* #else #ifdef CONFIG_SRCU */ + #ifdef CONFIG_DEBUG_LOCK_ALLOC /** diff --git a/init/main.c b/init/main.c index 53b278845b88..1bc5cc9e52ef 100644 --- a/init/main.c +++ b/init/main.c @@ -42,6 +42,7 @@ #include <linux/profile.h> #include <linux/kfence.h> #include <linux/rcupdate.h> +#include <linux/srcu.h> #include <linux/moduleparam.h> #include <linux/kallsyms.h> #include <linux/writeback.h> @@ -956,6 +957,7 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) tick_init(); rcu_init_nohz(); init_timers(); + srcu_init(); hrtimers_init(); softirq_init(); timekeeping_init(); diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index d64b842f4078..b3af34068051 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -422,12 +422,6 @@ do { \ #endif /* #if defined(CONFIG_SRCU) || !defined(CONFIG_TINY_RCU) */ -#ifdef CONFIG_SRCU -void srcu_init(void); -#else /* #ifdef CONFIG_SRCU */ -static inline void srcu_init(void) { } -#endif /* #else #ifdef CONFIG_SRCU */ - #ifdef CONFIG_TINY_RCU /* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */ static inline bool rcu_gp_is_normal(void) { return true; } diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 10e681ea7051..108f9ca06047 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1384,6 +1384,11 @@ void __init srcu_init(void) { struct srcu_struct *ssp; + /* + * Once that is set, call_srcu() can follow the normal path and + * queue delayed work. This must follow RCU workqueues creation + * and timers initialization. + */ srcu_init_done = true; while (!list_empty(&srcu_boot_list)) { ssp = list_first_entry(&srcu_boot_list, struct srcu_struct, diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c index c8a029fbb114..340b3f8b090d 100644 --- a/kernel/rcu/tiny.c +++ b/kernel/rcu/tiny.c @@ -221,5 +221,4 @@ void __init rcu_init(void) { open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); rcu_early_boot_tests(); - srcu_init(); } diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 5c214705c33f..740f5cd34459 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4714,7 +4714,6 @@ void __init rcu_init(void) WARN_ON(!rcu_gp_wq); rcu_par_gp_wq = alloc_workqueue("rcu_par_gp", WQ_MEM_RECLAIM, 0); WARN_ON(!rcu_par_gp_wq); - srcu_init(); /* Fill in default value for rcutree.qovld boot parameter. */ /* -After- the rcu_node ->lock fields are initialized! */ -- 2.25.1
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