drivers/xen/evtchn.c

File Facts

System

Linux kernel

Corpus path

drivers/xen/evtchn.c

Extension

.c

Size

16910 bytes

Lines

733

Domain

Driver Families

Bucket

drivers/xen

Inferred role

Driver Families: operation-table or driver-model contract

Status

pattern implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

• Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.
• 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.
• Touches IRQ or DMA behavior; this matters for the representative real-device path.
• 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/module.h
• linux/kernel.h
• linux/sched.h
• linux/slab.h
• linux/string.h
• linux/errno.h
• linux/fs.h
• linux/miscdevice.h
• linux/major.h
• linux/proc_fs.h
• linux/stat.h
• linux/poll.h
• linux/irq.h
• linux/init.h
• linux/mutex.h
• linux/cpu.h
• linux/mm.h
• linux/vmalloc.h
• xen/xen.h
• xen/events.h
• xen/evtchn.h
• xen/xen-ops.h
• asm/xen/hypervisor.h

Detected Declarations

• struct per_user_data
• struct user_evtchn
• function evtchn_free_ring
• function evtchn_ring_offset
• function add_evtchn
• function del_evtchn
• function evtchn_interrupt
• function evtchn_read
• function evtchn_write
• function evtchn_resize_ring
• function evtchn_bind_to_user
• function evtchn_unbind_from_user
• function evtchn_ioctl
• function evtchn_poll
• function evtchn_fasync
• function evtchn_open
• function evtchn_release
• function evtchn_init
• function evtchn_cleanup
• module init evtchn_init

Annotated Snippet

static const struct file_operations evtchn_fops = {
	.owner   = THIS_MODULE,
	.read    = evtchn_read,
	.write   = evtchn_write,
	.unlocked_ioctl = evtchn_ioctl,
	.poll    = evtchn_poll,
	.fasync  = evtchn_fasync,
	.open    = evtchn_open,
	.release = evtchn_release,
};

static struct miscdevice evtchn_miscdev = {
	.minor        = MISC_DYNAMIC_MINOR,
	.name         = "xen/evtchn",
	.fops         = &evtchn_fops,
};
static int __init evtchn_init(void)
{
	int err;

	if (!xen_domain())
		return -ENODEV;

	/* Create '/dev/xen/evtchn'. */
	err = misc_register(&evtchn_miscdev);
	if (err != 0) {
		pr_err("Could not register /dev/xen/evtchn\n");
		return err;
	}

	pr_info("Event-channel device installed\n");

	return 0;
}

static void __exit evtchn_cleanup(void)
{
	misc_deregister(&evtchn_miscdev);
}

module_init(evtchn_init);
module_exit(evtchn_cleanup);

MODULE_DESCRIPTION("Xen /dev/xen/evtchn device driver");
MODULE_LICENSE("GPL");

Annotation

• Immediate include surface: `linux/module.h`, `linux/kernel.h`, `linux/sched.h`, `linux/slab.h`, `linux/string.h`, `linux/errno.h`, `linux/fs.h`, `linux/miscdevice.h`.
• Detected declarations: `struct per_user_data`, `struct user_evtchn`, `function evtchn_free_ring`, `function evtchn_ring_offset`, `function add_evtchn`, `function del_evtchn`, `function evtchn_interrupt`, `function evtchn_read`, `function evtchn_write`, `function evtchn_resize_ring`.
• Atlas domain: Driver Families / drivers/xen.
• 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.
• IRQ or DMA behavior appears here, which is relevant to the selected PCIe/NVMe device path.

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.