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![Thomas Gleixner](/assets/img/avatar_default.png)
Based on 2 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Enrico Weigelt <info@metux.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
223 lines
5.3 KiB
C
223 lines
5.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* VFIO generic eventfd code for IRQFD support.
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* Derived from drivers/vfio/pci/vfio_pci_intrs.c
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*
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* Copyright (C) 2012 Red Hat, Inc. All rights reserved.
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* Author: Alex Williamson <alex.williamson@redhat.com>
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*/
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#include <linux/vfio.h>
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#include <linux/eventfd.h>
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#include <linux/file.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#define DRIVER_VERSION "0.1"
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#define DRIVER_AUTHOR "Alex Williamson <alex.williamson@redhat.com>"
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#define DRIVER_DESC "IRQFD support for VFIO bus drivers"
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static struct workqueue_struct *vfio_irqfd_cleanup_wq;
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static DEFINE_SPINLOCK(virqfd_lock);
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static int __init vfio_virqfd_init(void)
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{
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vfio_irqfd_cleanup_wq =
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create_singlethread_workqueue("vfio-irqfd-cleanup");
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if (!vfio_irqfd_cleanup_wq)
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return -ENOMEM;
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return 0;
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}
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static void __exit vfio_virqfd_exit(void)
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{
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destroy_workqueue(vfio_irqfd_cleanup_wq);
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}
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static void virqfd_deactivate(struct virqfd *virqfd)
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{
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queue_work(vfio_irqfd_cleanup_wq, &virqfd->shutdown);
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}
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static int virqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
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{
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struct virqfd *virqfd = container_of(wait, struct virqfd, wait);
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__poll_t flags = key_to_poll(key);
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if (flags & EPOLLIN) {
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/* An event has been signaled, call function */
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if ((!virqfd->handler ||
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virqfd->handler(virqfd->opaque, virqfd->data)) &&
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virqfd->thread)
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schedule_work(&virqfd->inject);
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}
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if (flags & EPOLLHUP) {
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unsigned long flags;
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spin_lock_irqsave(&virqfd_lock, flags);
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/*
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* The eventfd is closing, if the virqfd has not yet been
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* queued for release, as determined by testing whether the
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* virqfd pointer to it is still valid, queue it now. As
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* with kvm irqfds, we know we won't race against the virqfd
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* going away because we hold the lock to get here.
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*/
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if (*(virqfd->pvirqfd) == virqfd) {
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*(virqfd->pvirqfd) = NULL;
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virqfd_deactivate(virqfd);
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}
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spin_unlock_irqrestore(&virqfd_lock, flags);
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}
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return 0;
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}
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static void virqfd_ptable_queue_proc(struct file *file,
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wait_queue_head_t *wqh, poll_table *pt)
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{
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struct virqfd *virqfd = container_of(pt, struct virqfd, pt);
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add_wait_queue(wqh, &virqfd->wait);
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}
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static void virqfd_shutdown(struct work_struct *work)
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{
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struct virqfd *virqfd = container_of(work, struct virqfd, shutdown);
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u64 cnt;
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eventfd_ctx_remove_wait_queue(virqfd->eventfd, &virqfd->wait, &cnt);
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flush_work(&virqfd->inject);
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eventfd_ctx_put(virqfd->eventfd);
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kfree(virqfd);
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}
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static void virqfd_inject(struct work_struct *work)
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{
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struct virqfd *virqfd = container_of(work, struct virqfd, inject);
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if (virqfd->thread)
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virqfd->thread(virqfd->opaque, virqfd->data);
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}
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int vfio_virqfd_enable(void *opaque,
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int (*handler)(void *, void *),
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void (*thread)(void *, void *),
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void *data, struct virqfd **pvirqfd, int fd)
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{
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struct fd irqfd;
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struct eventfd_ctx *ctx;
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struct virqfd *virqfd;
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int ret = 0;
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__poll_t events;
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virqfd = kzalloc(sizeof(*virqfd), GFP_KERNEL);
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if (!virqfd)
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return -ENOMEM;
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virqfd->pvirqfd = pvirqfd;
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virqfd->opaque = opaque;
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virqfd->handler = handler;
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virqfd->thread = thread;
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virqfd->data = data;
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INIT_WORK(&virqfd->shutdown, virqfd_shutdown);
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INIT_WORK(&virqfd->inject, virqfd_inject);
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irqfd = fdget(fd);
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if (!irqfd.file) {
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ret = -EBADF;
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goto err_fd;
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}
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ctx = eventfd_ctx_fileget(irqfd.file);
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if (IS_ERR(ctx)) {
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ret = PTR_ERR(ctx);
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goto err_ctx;
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}
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virqfd->eventfd = ctx;
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/*
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* virqfds can be released by closing the eventfd or directly
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* through ioctl. These are both done through a workqueue, so
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* we update the pointer to the virqfd under lock to avoid
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* pushing multiple jobs to release the same virqfd.
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*/
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spin_lock_irq(&virqfd_lock);
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if (*pvirqfd) {
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spin_unlock_irq(&virqfd_lock);
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ret = -EBUSY;
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goto err_busy;
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}
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*pvirqfd = virqfd;
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spin_unlock_irq(&virqfd_lock);
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/*
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* Install our own custom wake-up handling so we are notified via
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* a callback whenever someone signals the underlying eventfd.
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*/
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init_waitqueue_func_entry(&virqfd->wait, virqfd_wakeup);
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init_poll_funcptr(&virqfd->pt, virqfd_ptable_queue_proc);
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events = vfs_poll(irqfd.file, &virqfd->pt);
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/*
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* Check if there was an event already pending on the eventfd
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* before we registered and trigger it as if we didn't miss it.
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*/
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if (events & EPOLLIN) {
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if ((!handler || handler(opaque, data)) && thread)
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schedule_work(&virqfd->inject);
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}
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/*
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* Do not drop the file until the irqfd is fully initialized,
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* otherwise we might race against the EPOLLHUP.
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*/
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fdput(irqfd);
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return 0;
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err_busy:
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eventfd_ctx_put(ctx);
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err_ctx:
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fdput(irqfd);
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err_fd:
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kfree(virqfd);
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return ret;
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}
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EXPORT_SYMBOL_GPL(vfio_virqfd_enable);
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void vfio_virqfd_disable(struct virqfd **pvirqfd)
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{
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unsigned long flags;
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spin_lock_irqsave(&virqfd_lock, flags);
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if (*pvirqfd) {
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virqfd_deactivate(*pvirqfd);
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*pvirqfd = NULL;
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}
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spin_unlock_irqrestore(&virqfd_lock, flags);
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/*
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* Block until we know all outstanding shutdown jobs have completed.
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* Even if we don't queue the job, flush the wq to be sure it's
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* been released.
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*/
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flush_workqueue(vfio_irqfd_cleanup_wq);
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}
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EXPORT_SYMBOL_GPL(vfio_virqfd_disable);
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module_init(vfio_virqfd_init);
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module_exit(vfio_virqfd_exit);
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MODULE_VERSION(DRIVER_VERSION);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR(DRIVER_AUTHOR);
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MODULE_DESCRIPTION(DRIVER_DESC);
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