Merge branch 'rcu-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (49b550fe) · Commits · 戴 / test

include/linux/rcupdate.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -444,6 +444,10 @@ bool __rcu_is_watching(void);
		#error "Unknown RCU implementation specified to kernel configuration"
		#endif

		#define RCU_SCHEDULER_INACTIVE 0
		#define RCU_SCHEDULER_INIT 1
		#define RCU_SCHEDULER_RUNNING 2

		/*
		* init_rcu_head_on_stack()/destroy_rcu_head_on_stack() are needed for dynamic
		* initialization and destruction of rcu_head on the stack. rcu_head structures

kernel/rcu/rcu.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -136,6 +136,7 @@ int rcu_jiffies_till_stall_check(void);
		#define TPS(x) tracepoint_string(x)

		void rcu_early_boot_tests(void);
		void rcu_test_sync_prims(void);

		/*
		* This function really isn't for public consumption, but RCU is special in

kernel/rcu/tiny.c

+0 −4

Original line number	Diff line number	Diff line
		@@ -185,9 +185,6 @@ static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused
		* benefits of doing might_sleep() to reduce latency.)
		*
		* Cool, huh? (Due to Josh Triplett.)
		*
		* But we want to make this a static inline later. The cond_resched()
		* currently makes this problematic.
		*/
		void synchronize_sched(void)
		{
		@@ -195,7 +192,6 @@ void synchronize_sched(void)
		lock_is_held(&rcu_lock_map) \|\|
		lock_is_held(&rcu_sched_lock_map),
		"Illegal synchronize_sched() in RCU read-side critical section");
		cond_resched();
		}
		EXPORT_SYMBOL_GPL(synchronize_sched);

kernel/rcu/tiny_plugin.h

+7 −2

Original line number	Diff line number	Diff line
		@@ -60,12 +60,17 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active);

		/*
		* During boot, we forgive RCU lockdep issues. After this function is
		* invoked, we start taking RCU lockdep issues seriously.
		* invoked, we start taking RCU lockdep issues seriously. Note that unlike
		* Tree RCU, Tiny RCU transitions directly from RCU_SCHEDULER_INACTIVE
		* to RCU_SCHEDULER_RUNNING, skipping the RCU_SCHEDULER_INIT stage.
		* The reason for this is that Tiny RCU does not need kthreads, so does
		* not have to care about the fact that the scheduler is half-initialized
		* at a certain phase of the boot process.
		*/
		void __init rcu_scheduler_starting(void)
		{
		WARN_ON(nr_context_switches() > 0);
		rcu_scheduler_active = 1;
		rcu_scheduler_active = RCU_SCHEDULER_RUNNING;
		}

		#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */

kernel/rcu/tree.c

+20 −13

Original line number	Diff line number	Diff line
		@@ -127,13 +127,16 @@ int rcu_num_nodes __read_mostly = NUM_RCU_NODES; /* Total # rcu_nodes in use. */
		int sysctl_panic_on_rcu_stall __read_mostly;

		/*
		* The rcu_scheduler_active variable transitions from zero to one just
		* before the first task is spawned. So when this variable is zero, RCU
		* can assume that there is but one task, allowing RCU to (for example)
		* The rcu_scheduler_active variable is initialized to the value
		* RCU_SCHEDULER_INACTIVE and transitions RCU_SCHEDULER_INIT just before the
		* first task is spawned. So when this variable is RCU_SCHEDULER_INACTIVE,
		* RCU can assume that there is but one task, allowing RCU to (for example)
		* optimize synchronize_rcu() to a simple barrier(). When this variable
		* is one, RCU must actually do all the hard work required to detect real
		* grace periods. This variable is also used to suppress boot-time false
		* positives from lockdep-RCU error checking.
		* is RCU_SCHEDULER_INIT, RCU must actually do all the hard work required
		* to detect real grace periods. This variable is also used to suppress
		* boot-time false positives from lockdep-RCU error checking. Finally, it
		* transitions from RCU_SCHEDULER_INIT to RCU_SCHEDULER_RUNNING after RCU
		* is fully initialized, including all of its kthreads having been spawned.
		*/
		int rcu_scheduler_active __read_mostly;
		EXPORT_SYMBOL_GPL(rcu_scheduler_active);
		@@ -3980,18 +3983,22 @@ static int __init rcu_spawn_gp_kthread(void)
		early_initcall(rcu_spawn_gp_kthread);

		/*
		* This function is invoked towards the end of the scheduler's initialization
		* process. Before this is called, the idle task might contain
		* RCU read-side critical sections (during which time, this idle
		* task is booting the system). After this function is called, the
		* idle tasks are prohibited from containing RCU read-side critical
		* sections. This function also enables RCU lockdep checking.
		* This function is invoked towards the end of the scheduler's
		* initialization process. Before this is called, the idle task might
		* contain synchronous grace-period primitives (during which time, this idle
		* task is booting the system, and such primitives are no-ops). After this
		* function is called, any synchronous grace-period primitives are run as
		* expedited, with the requesting task driving the grace period forward.
		* A later core_initcall() rcu_exp_runtime_mode() will switch to full
		* runtime RCU functionality.
		*/
		void rcu_scheduler_starting(void)
		{
		WARN_ON(num_online_cpus() != 1);
		WARN_ON(nr_context_switches() > 0);
		rcu_scheduler_active = 1;
		rcu_test_sync_prims();
		rcu_scheduler_active = RCU_SCHEDULER_INIT;
		rcu_test_sync_prims();
		}

		/*

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