fs/signalfd.c

File Facts

System

Linux kernel

Corpus path

fs/signalfd.c

Extension

.c

Size

8849 bytes

Lines

352

Domain

Core OS

Bucket

VFS And Filesystem Core

Inferred role

Core OS: syscall or user/kernel boundary

Status

core 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 or participates in a user/kernel boundary; inspect argument validation, copy_from_user/copy_to_user, credentials, and dispatch target.
• 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.
• Allocates kernel memory; connect allocation flags and lifetime to context constraints.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/file.h
• linux/poll.h
• linux/init.h
• linux/fs.h
• linux/sched.h
• linux/slab.h
• linux/kernel.h
• linux/signal.h
• linux/list.h
• linux/anon_inodes.h
• linux/signalfd.h
• linux/syscalls.h
• linux/proc_fs.h
• linux/compat.h

Detected Declarations

• syscall signalfd4
• syscall signalfd
• struct signalfd_ctx
• function Copyright
• function signalfd_release
• function signalfd_poll
• function copy_siginfo_to_user
• function signalfd_dequeue
• function signalfd_read_iter
• function signalfd_show_fdinfo
• function do_signalfd4
• function do_compat_signalfd4

Annotated Snippet

SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
		size_t, sizemask, int, flags)
{
	sigset_t mask;

	if (sizemask != sizeof(sigset_t))
		return -EINVAL;
	if (copy_from_user(&mask, user_mask, sizeof(mask)))
		return -EFAULT;
	return do_signalfd4(ufd, &mask, flags);
}

SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
		size_t, sizemask)
{
	sigset_t mask;

	if (sizemask != sizeof(sigset_t))
		return -EINVAL;
	if (copy_from_user(&mask, user_mask, sizeof(mask)))
		return -EFAULT;
	return do_signalfd4(ufd, &mask, 0);
}

#ifdef CONFIG_COMPAT
static long do_compat_signalfd4(int ufd,
			const compat_sigset_t __user *user_mask,
			compat_size_t sigsetsize, int flags)
{
	sigset_t mask;

	if (sigsetsize != sizeof(compat_sigset_t))
		return -EINVAL;
	if (get_compat_sigset(&mask, user_mask))
		return -EFAULT;
	return do_signalfd4(ufd, &mask, flags);
}

COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd,
		     const compat_sigset_t __user *, user_mask,
		     compat_size_t, sigsetsize,
		     int, flags)
{
	return do_compat_signalfd4(ufd, user_mask, sigsetsize, flags);
}

COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd,
		     const compat_sigset_t __user *, user_mask,
		     compat_size_t, sigsetsize)
{
	return do_compat_signalfd4(ufd, user_mask, sigsetsize, 0);
}
#endif

Annotation

• Immediate include surface: `linux/file.h`, `linux/poll.h`, `linux/init.h`, `linux/fs.h`, `linux/sched.h`, `linux/slab.h`, `linux/kernel.h`, `linux/signal.h`.
• Detected declarations: `syscall signalfd4`, `syscall signalfd`, `struct signalfd_ctx`, `function Copyright`, `function signalfd_release`, `function signalfd_poll`, `function copy_siginfo_to_user`, `function signalfd_dequeue`, `function signalfd_read_iter`, `function signalfd_show_fdinfo`.
• Atlas domain: Core OS / VFS And Filesystem Core.
• Implementation status: core 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.