include/linux/rcu_sync.h

File Facts

System

Linux kernel

Corpus path

include/linux/rcu_sync.h

Extension

.h

Size

1441 bytes

Lines

54

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.

• Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.
• Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/wait.h
• linux/rcupdate.h

Detected Declarations

• struct rcu_sync
• function rcu_sync_is_idle

Annotated Snippet

struct rcu_sync {
	int			gp_state;
	int			gp_count;
	wait_queue_head_t	gp_wait;

	struct rcu_head		cb_head;
};

/**
 * rcu_sync_is_idle() - Are readers permitted to use their fastpaths?
 * @rsp: Pointer to rcu_sync structure to use for synchronization
 *
 * Returns true if readers are permitted to use their fastpaths.  Must be
 * invoked within some flavor of RCU read-side critical section.
 */
static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
{
	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
			 "suspicious rcu_sync_is_idle() usage");
	return !READ_ONCE(rsp->gp_state); /* GP_IDLE */
}

extern void rcu_sync_init(struct rcu_sync *);
extern void rcu_sync_enter(struct rcu_sync *);
extern void rcu_sync_exit(struct rcu_sync *);
extern void rcu_sync_dtor(struct rcu_sync *);

#define __RCU_SYNC_INITIALIZER(name) {					\
		.gp_state = 0,						\
		.gp_count = 0,						\
		.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait),	\
	}

#define	DEFINE_RCU_SYNC(name)	\
	struct rcu_sync name = __RCU_SYNC_INITIALIZER(name)

#endif /* _LINUX_RCU_SYNC_H_ */

Annotation

• Immediate include surface: `linux/wait.h`, `linux/rcupdate.h`.
• Detected declarations: `struct rcu_sync`, `function rcu_sync_is_idle`.
• Atlas domain: Core OS / Core Kernel Interface.
• Implementation status: source implementation candidate.
• Synchronization appears in or near this file; preserve lock ordering, sleepability, and interrupt-context constraints.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.