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Merge branch 'vfs-6.15.eventpoll' of https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs into for-6.15/io_uring-epoll-wait

Browse source 
Merge epoll changes from the VFS tree, which the io_uring changes depend
on.

* 'vfs-6.15.eventpoll' of https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  eventpoll: add epoll_sendevents() helper
  eventpoll: abstract out ep_try_send_events() helper
  eventpoll: abstract out parameter sanity checking
This commit is contained in:
Jens Axboe 2025-02-20 07:59:38 -07:00
commit 08b40b7a10
2 changed files with 67 additions and 24 deletions
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87
fs/eventpoll.c
View file

@ -1980,6 +1980,22 @@ static int ep_autoremove_wake_function(struct wait_queue_entry *wq_entry,
return ret;
}
static int ep_try_send_events(struct eventpoll *ep,
struct epoll_event __user *events, int maxevents)
{
int res;
/*
* Try to transfer events to user space. In case we get 0 events and
* there's still timeout left over, we go trying again in search of
* more luck.
*/
res = ep_send_events(ep, events, maxevents);
if (res > 0)
ep_suspend_napi_irqs(ep);
return res;
}
/**
* ep_poll - Retrieves ready events, and delivers them to the caller-supplied
* event buffer.
@ -2031,17 +2047,9 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
while (1) {
if (eavail) {
/*
* Try to transfer events to user space. In case we get
* 0 events and there's still timeout left over, we go
* trying again in search of more luck.
*/
res = ep_send_events(ep, events, maxevents);
if (res) {
if (res > 0)
ep_suspend_napi_irqs(ep);
res = ep_try_send_events(ep, events, maxevents);
if (res)
return res;
}
}
if (timed_out)
@ -2445,6 +2453,47 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
return do_epoll_ctl(epfd, op, fd, &epds, false);
}
static int ep_check_params(struct file *file, struct epoll_event __user *evs,
int maxevents)
{
/* The maximum number of event must be greater than zero */
if (maxevents <= 0 || maxevents > EP_MAX_EVENTS)
return -EINVAL;
/* Verify that the area passed by the user is writeable */
if (!access_ok(evs, maxevents * sizeof(struct epoll_event)))
return -EFAULT;
/*
* We have to check that the file structure underneath the fd
* the user passed to us _is_ an eventpoll file.
*/
if (!is_file_epoll(file))
return -EINVAL;
return 0;
}
int epoll_sendevents(struct file *file, struct epoll_event __user *events,
int maxevents)
{
struct eventpoll *ep;
int ret;
ret = ep_check_params(file, events, maxevents);
if (unlikely(ret))
return ret;
ep = file->private_data;
/*
* Racy call, but that's ok - it should get retried based on
* poll readiness anyway.
*/
if (ep_events_available(ep))
return ep_try_send_events(ep, events, maxevents);
return 0;
}
/*
* Implement the event wait interface for the eventpoll file. It is the kernel
* part of the user space epoll_wait(2).
@ -2453,26 +2502,16 @@ static int do_epoll_wait(int epfd, struct epoll_event __user *events,
int maxevents, struct timespec64 *to)
{
struct eventpoll *ep;
/* The maximum number of event must be greater than zero */
if (maxevents <= 0 || maxevents > EP_MAX_EVENTS)
return -EINVAL;
/* Verify that the area passed by the user is writeable */
if (!access_ok(events, maxevents * sizeof(struct epoll_event)))
return -EFAULT;
int ret;
/* Get the "struct file *" for the eventpoll file */
CLASS(fd, f)(epfd);
if (fd_empty(f))
return -EBADF;
/*
* We have to check that the file structure underneath the fd
* the user passed to us _is_ an eventpoll file.
*/
if (!is_file_epoll(fd_file(f)))
return -EINVAL;
ret = ep_check_params(fd_file(f), events, maxevents);
if (unlikely(ret))
return ret;
/*
* At this point it is safe to assume that the "private_data" contains

4
include/linux/eventpoll.h
View file

@ -25,6 +25,10 @@ struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long t
/* Used to release the epoll bits inside the "struct file" */
void eventpoll_release_file(struct file *file);
/* Copy ready events to userspace */
int epoll_sendevents(struct file *file, struct epoll_event __user *events,
int maxevents);
/*
* This is called from inside fs/file_table.c:__fput() to unlink files
* from the eventpoll interface. We need to have this facility to cleanup