include/linux/srcutiny.h

Source file repositories/reference/linux-study-clean/include/linux/srcutiny.h

File Facts

System
Linux kernel
Corpus path
include/linux/srcutiny.h
Extension
.h
Size
5204 bytes
Lines
158
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct srcu_struct {
	short srcu_lock_nesting[2];	/* srcu_read_lock() nesting depth. */
	u8 srcu_gp_running;		/* GP workqueue running? */
	u8 srcu_gp_waiting;		/* GP waiting for readers? */
	unsigned long srcu_idx;		/* Current reader array element in bit 0x2. */
	unsigned long srcu_idx_max;	/* Furthest future srcu_idx request. */
	struct swait_queue_head srcu_wq;
					/* Last srcu_read_unlock() wakes GP. */
	struct rcu_head *srcu_cb_head;	/* Pending callbacks: Head. */
	struct rcu_head **srcu_cb_tail;	/* Pending callbacks: Tail. */
	struct work_struct srcu_work;	/* For driving grace periods. */
	struct irq_work srcu_irq_work;	/* Defer schedule_work() to irq work. */
#ifdef CONFIG_DEBUG_LOCK_ALLOC
	struct lockdep_map dep_map;
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
};

void srcu_drive_gp(struct work_struct *wp);
void srcu_tiny_irq_work(struct irq_work *irq_work);

#define __SRCU_STRUCT_INIT(name, __ignored, ___ignored, ____ignored)	\
{									\
	.srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq),	\
	.srcu_cb_tail = &name.srcu_cb_head,				\
	.srcu_work = __WORK_INITIALIZER(name.srcu_work, srcu_drive_gp),	\
	.srcu_irq_work = { .func = srcu_tiny_irq_work },		\
	__SRCU_DEP_MAP_INIT(name)					\
}

/*
 * This odd _STATIC_ arrangement is needed for API compatibility with
 * Tree SRCU, which needs some per-CPU data.
 */
#define DEFINE_SRCU(name) \
	struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name, name)
#define DEFINE_STATIC_SRCU(name) \
	static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name, name)
#define DEFINE_SRCU_FAST(name) DEFINE_SRCU(name)
#define DEFINE_STATIC_SRCU_FAST(name) \
	static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name, name)
#define DEFINE_SRCU_FAST_UPDOWN(name) DEFINE_SRCU(name)
#define DEFINE_STATIC_SRCU_FAST_UPDOWN(name) \
	static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name, name)

// Dummy structure for srcu_notifier_head.
struct srcu_usage { };
#define __SRCU_USAGE_INIT(name) { }
#define __init_srcu_struct_fast __init_srcu_struct
#define __init_srcu_struct_fast_updown __init_srcu_struct
#ifndef CONFIG_DEBUG_LOCK_ALLOC
#define init_srcu_struct_fast init_srcu_struct
#define init_srcu_struct_fast_updown init_srcu_struct
#endif // #ifndef CONFIG_DEBUG_LOCK_ALLOC

void synchronize_srcu(struct srcu_struct *ssp);

/*
 * Counts the new reader in the appropriate per-CPU element of the
 * srcu_struct.  Can be invoked from irq/bh handlers, but the matching
 * __srcu_read_unlock() must be in the same handler instance.  Returns an
 * index that must be passed to the matching srcu_read_unlock().
 */
static inline int __srcu_read_lock(struct srcu_struct *ssp)
	__acquires_shared(ssp)
{
	int idx;

	preempt_disable();  // Needed for PREEMPT_LAZY
	idx = ((READ_ONCE(ssp->srcu_idx) + 1) & 0x2) >> 1;
	WRITE_ONCE(ssp->srcu_lock_nesting[idx], READ_ONCE(ssp->srcu_lock_nesting[idx]) + 1);
	preempt_enable();
	__acquire_shared(ssp);
	return idx;
}

struct srcu_ctr;

static inline bool __srcu_ptr_to_ctr(struct srcu_struct *ssp, struct srcu_ctr __percpu *scpp)
{
	return (int)(intptr_t)(struct srcu_ctr __force __kernel *)scpp;
}

static inline struct srcu_ctr __percpu *__srcu_ctr_to_ptr(struct srcu_struct *ssp, int idx)
{
	return (struct srcu_ctr __percpu *)(intptr_t)idx;
}

static inline struct srcu_ctr __percpu *__srcu_read_lock_fast(struct srcu_struct *ssp)
	__acquires_shared(ssp)
{

Annotation

Implementation Notes