kernel/time/test_udelay.c

File Facts

System

Linux kernel

Corpus path

kernel/time/test_udelay.c

Extension

.c

Size

3738 bytes

Lines

161

Domain

Core OS

Bucket

Scheduler, Processes, Timers, Sync, And Syscalls

Inferred role

Core OS: operation-table or driver-model contract

Status

pattern 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.
• Defines an operation table; this is where Linux turns generic core objects into subsystem-specific behavior.
• Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.
• 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/debugfs.h
• linux/delay.h
• linux/ktime.h
• linux/module.h
• linux/uaccess.h

Detected Declarations

• function udelay_test_single
• function udelay_test_show
• function udelay_test_open
• function udelay_test_write
• function udelay_test_init
• function udelay_test_exit
• module init udelay_test_init

Annotated Snippet

static const struct file_operations udelay_test_debugfs_ops = {
	.owner = THIS_MODULE,
	.open = udelay_test_open,
	.read = seq_read,
	.write = udelay_test_write,
	.llseek = seq_lseek,
	.release = single_release,
};

static int __init udelay_test_init(void)
{
	mutex_lock(&udelay_test_lock);
	debugfs_create_file(DEBUGFS_FILENAME, S_IRUSR, NULL, NULL,
			    &udelay_test_debugfs_ops);
	mutex_unlock(&udelay_test_lock);

	return 0;
}

module_init(udelay_test_init);

static void __exit udelay_test_exit(void)
{
	mutex_lock(&udelay_test_lock);
	debugfs_lookup_and_remove(DEBUGFS_FILENAME, NULL);
	mutex_unlock(&udelay_test_lock);
}

module_exit(udelay_test_exit);

MODULE_DESCRIPTION("udelay test module");
MODULE_AUTHOR("David Riley <davidriley@chromium.org>");
MODULE_LICENSE("GPL");

Annotation

• Immediate include surface: `linux/debugfs.h`, `linux/delay.h`, `linux/ktime.h`, `linux/module.h`, `linux/uaccess.h`.
• Detected declarations: `function udelay_test_single`, `function udelay_test_show`, `function udelay_test_open`, `function udelay_test_write`, `function udelay_test_init`, `function udelay_test_exit`, `module init udelay_test_init`.
• Atlas domain: Core OS / Scheduler, Processes, Timers, Sync, And Syscalls.
• Implementation status: pattern implementation candidate.
• This snippet crosses the user/kernel memory boundary; validate fault handling and access checks before translating the pattern.
• 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.