linux-stable/drivers/vfio/virqfd.c
Linus Torvalds a9a08845e9 vfs: do bulk POLL* -> EPOLL* replacement
This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:

    for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
        L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
        for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
    done

with de-mangling cleanups yet to come.

NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do.  But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.

The next patch from Al will sort out the final differences, and we
should be all done.

Scripted-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-11 14:34:03 -08:00

226 lines
5.5 KiB
C

/*
* VFIO generic eventfd code for IRQFD support.
* Derived from drivers/vfio/pci/vfio_pci_intrs.c
*
* Copyright (C) 2012 Red Hat, Inc. All rights reserved.
* Author: Alex Williamson <alex.williamson@redhat.com>
*
* 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.
*/
#include <linux/vfio.h>
#include <linux/eventfd.h>
#include <linux/file.h>
#include <linux/module.h>
#include <linux/slab.h>
#define DRIVER_VERSION "0.1"
#define DRIVER_AUTHOR "Alex Williamson <alex.williamson@redhat.com>"
#define DRIVER_DESC "IRQFD support for VFIO bus drivers"
static struct workqueue_struct *vfio_irqfd_cleanup_wq;
static DEFINE_SPINLOCK(virqfd_lock);
static int __init vfio_virqfd_init(void)
{
vfio_irqfd_cleanup_wq =
create_singlethread_workqueue("vfio-irqfd-cleanup");
if (!vfio_irqfd_cleanup_wq)
return -ENOMEM;
return 0;
}
static void __exit vfio_virqfd_exit(void)
{
destroy_workqueue(vfio_irqfd_cleanup_wq);
}
static void virqfd_deactivate(struct virqfd *virqfd)
{
queue_work(vfio_irqfd_cleanup_wq, &virqfd->shutdown);
}
static int virqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
{
struct virqfd *virqfd = container_of(wait, struct virqfd, wait);
__poll_t flags = key_to_poll(key);
if (flags & EPOLLIN) {
/* An event has been signaled, call function */
if ((!virqfd->handler ||
virqfd->handler(virqfd->opaque, virqfd->data)) &&
virqfd->thread)
schedule_work(&virqfd->inject);
}
if (flags & EPOLLHUP) {
unsigned long flags;
spin_lock_irqsave(&virqfd_lock, flags);
/*
* The eventfd is closing, if the virqfd has not yet been
* queued for release, as determined by testing whether the
* virqfd pointer to it is still valid, queue it now. As
* with kvm irqfds, we know we won't race against the virqfd
* going away because we hold the lock to get here.
*/
if (*(virqfd->pvirqfd) == virqfd) {
*(virqfd->pvirqfd) = NULL;
virqfd_deactivate(virqfd);
}
spin_unlock_irqrestore(&virqfd_lock, flags);
}
return 0;
}
static void virqfd_ptable_queue_proc(struct file *file,
wait_queue_head_t *wqh, poll_table *pt)
{
struct virqfd *virqfd = container_of(pt, struct virqfd, pt);
add_wait_queue(wqh, &virqfd->wait);
}
static void virqfd_shutdown(struct work_struct *work)
{
struct virqfd *virqfd = container_of(work, struct virqfd, shutdown);
u64 cnt;
eventfd_ctx_remove_wait_queue(virqfd->eventfd, &virqfd->wait, &cnt);
flush_work(&virqfd->inject);
eventfd_ctx_put(virqfd->eventfd);
kfree(virqfd);
}
static void virqfd_inject(struct work_struct *work)
{
struct virqfd *virqfd = container_of(work, struct virqfd, inject);
if (virqfd->thread)
virqfd->thread(virqfd->opaque, virqfd->data);
}
int vfio_virqfd_enable(void *opaque,
int (*handler)(void *, void *),
void (*thread)(void *, void *),
void *data, struct virqfd **pvirqfd, int fd)
{
struct fd irqfd;
struct eventfd_ctx *ctx;
struct virqfd *virqfd;
int ret = 0;
__poll_t events;
virqfd = kzalloc(sizeof(*virqfd), GFP_KERNEL);
if (!virqfd)
return -ENOMEM;
virqfd->pvirqfd = pvirqfd;
virqfd->opaque = opaque;
virqfd->handler = handler;
virqfd->thread = thread;
virqfd->data = data;
INIT_WORK(&virqfd->shutdown, virqfd_shutdown);
INIT_WORK(&virqfd->inject, virqfd_inject);
irqfd = fdget(fd);
if (!irqfd.file) {
ret = -EBADF;
goto err_fd;
}
ctx = eventfd_ctx_fileget(irqfd.file);
if (IS_ERR(ctx)) {
ret = PTR_ERR(ctx);
goto err_ctx;
}
virqfd->eventfd = ctx;
/*
* virqfds can be released by closing the eventfd or directly
* through ioctl. These are both done through a workqueue, so
* we update the pointer to the virqfd under lock to avoid
* pushing multiple jobs to release the same virqfd.
*/
spin_lock_irq(&virqfd_lock);
if (*pvirqfd) {
spin_unlock_irq(&virqfd_lock);
ret = -EBUSY;
goto err_busy;
}
*pvirqfd = virqfd;
spin_unlock_irq(&virqfd_lock);
/*
* Install our own custom wake-up handling so we are notified via
* a callback whenever someone signals the underlying eventfd.
*/
init_waitqueue_func_entry(&virqfd->wait, virqfd_wakeup);
init_poll_funcptr(&virqfd->pt, virqfd_ptable_queue_proc);
events = irqfd.file->f_op->poll(irqfd.file, &virqfd->pt);
/*
* Check if there was an event already pending on the eventfd
* before we registered and trigger it as if we didn't miss it.
*/
if (events & EPOLLIN) {
if ((!handler || handler(opaque, data)) && thread)
schedule_work(&virqfd->inject);
}
/*
* Do not drop the file until the irqfd is fully initialized,
* otherwise we might race against the EPOLLHUP.
*/
fdput(irqfd);
return 0;
err_busy:
eventfd_ctx_put(ctx);
err_ctx:
fdput(irqfd);
err_fd:
kfree(virqfd);
return ret;
}
EXPORT_SYMBOL_GPL(vfio_virqfd_enable);
void vfio_virqfd_disable(struct virqfd **pvirqfd)
{
unsigned long flags;
spin_lock_irqsave(&virqfd_lock, flags);
if (*pvirqfd) {
virqfd_deactivate(*pvirqfd);
*pvirqfd = NULL;
}
spin_unlock_irqrestore(&virqfd_lock, flags);
/*
* Block until we know all outstanding shutdown jobs have completed.
* Even if we don't queue the job, flush the wq to be sure it's
* been released.
*/
flush_workqueue(vfio_irqfd_cleanup_wq);
}
EXPORT_SYMBOL_GPL(vfio_virqfd_disable);
module_init(vfio_virqfd_init);
module_exit(vfio_virqfd_exit);
MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);