Commit 8e9c01c7 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Paul E. McKenney
Browse files

srcu: Initialize SRCU after timers 



Once srcu_init() is called, the SRCU core will make use of delayed
workqueues, which rely on timers.  However init_timers() is called
several steps after rcu_init().  This means that a call_srcu() after
rcu_init() but before init_timers() would find itself within a dangerously
uninitialized timer core.

This commit therefore creates a separate call to srcu_init() after
init_timer() completes, which ensures that we stay in early SRCU mode
until timers are safe(r).

Signed-off-by: default avatarFrederic 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>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 7bf0a614

include/linux/srcu.h

+6 −0
Original line number Diff line number Diff line
@@ -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



/**

init/main.c

+2 −0
Original line number Diff line number Diff line
@@ -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>
@@ -979,6 +980,7 @@ 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();

kernel/rcu/rcu.h

+0 −6
Original line number Diff line number Diff line
@@ -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; }

kernel/rcu/srcutree.c

+5 −0
Original line number Diff line number Diff line
@@ -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,

kernel/rcu/tiny.c

+0 −1
Original line number Diff line number Diff line
@@ -221,5 +221,4 @@ void __init rcu_init(void) 
{

	open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);

	rcu_early_boot_tests();

	srcu_init();

}