include/linux/stackdepot.h

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

File Facts

System
Linux kernel
Corpus path
include/linux/stackdepot.h
Extension
.h
Size
9165 bytes
Lines
258
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 stack_record {
	struct list_head hash_list;	/* Links in the hash table */
	u32 hash;			/* Hash in hash table */
	u32 size;			/* Number of stored frames */
	union handle_parts handle;	/* Constant after initialization */
	refcount_t count;
	union {
		unsigned long entries[CONFIG_STACKDEPOT_MAX_FRAMES];	/* Frames */
		struct {
			/*
			 * An important invariant of the implementation is to
			 * only place a stack record onto the freelist iff its
			 * refcount is zero. Because stack records with a zero
			 * refcount are never considered as valid, it is safe to
			 * union @entries and freelist management state below.
			 * Conversely, as soon as an entry is off the freelist
			 * and its refcount becomes non-zero, the below must not
			 * be accessed until being placed back on the freelist.
			 */
			struct list_head free_list;	/* Links in the freelist */
			unsigned long rcu_state;	/* RCU cookie */
		};
	};
};
#endif

typedef u32 depot_flags_t;

/*
 * Flags that can be passed to stack_depot_save_flags(); see the comment next
 * to its declaration for more details.
 */
#define STACK_DEPOT_FLAG_CAN_ALLOC	((depot_flags_t)0x0001)
#define STACK_DEPOT_FLAG_GET		((depot_flags_t)0x0002)

#define STACK_DEPOT_FLAGS_NUM	2
#define STACK_DEPOT_FLAGS_MASK	((depot_flags_t)((1 << STACK_DEPOT_FLAGS_NUM) - 1))

/*
 * Using stack depot requires its initialization, which can be done in 3 ways:
 *
 * 1. Selecting CONFIG_STACKDEPOT_ALWAYS_INIT. This option is suitable in
 *    scenarios where it's known at compile time that stack depot will be used.
 *    Enabling this config makes the kernel initialize stack depot in mm_init().
 *
 * 2. Calling stack_depot_request_early_init() during early boot, before
 *    stack_depot_early_init() in mm_init() completes. For example, this can
 *    be done when evaluating kernel boot parameters.
 *
 * 3. Calling stack_depot_init(). Possible after boot is complete. This option
 *    is recommended for modules initialized later in the boot process, after
 *    mm_init() completes.
 *
 * stack_depot_init() and stack_depot_request_early_init() can be called
 * regardless of whether CONFIG_STACKDEPOT is enabled and are no-op when this
 * config is disabled. The save/fetch/print stack depot functions can only be
 * called from the code that makes sure CONFIG_STACKDEPOT is enabled _and_
 * initializes stack depot via one of the ways listed above.
 */
#ifdef CONFIG_STACKDEPOT
int stack_depot_init(void);

void __init stack_depot_request_early_init(void);

/* Must be only called from mm_init(). */
int __init stack_depot_early_init(void);
#else
static inline int stack_depot_init(void) { return 0; }

static inline void stack_depot_request_early_init(void) { }

static inline int stack_depot_early_init(void)	{ return 0; }
#endif

/**
 * stack_depot_save_flags - Save a stack trace to stack depot
 *
 * @entries:		Pointer to the stack trace
 * @nr_entries:		Number of frames in the stack
 * @alloc_flags:	Allocation GFP flags
 * @depot_flags:	Stack depot flags
 *
 * Saves a stack trace from @entries array of size @nr_entries.
 *
 * If STACK_DEPOT_FLAG_CAN_ALLOC is set in @depot_flags, stack depot can
 * replenish the stack pools in case no space is left (allocates using GFP
 * flags of @alloc_flags). Otherwise, stack depot avoids any allocations and
 * fails if no space is left to store the stack trace.
 *
 * If STACK_DEPOT_FLAG_GET is set in @depot_flags, stack depot will increment

Annotation

Implementation Notes