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eventpoll: add file based control interface

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Add do_epoll_ctl_file(), which takes a pre-resolved epoll file and a
struct epoll_filefd for the target rather than two integer file
descriptors. do_epoll_ctl() remains as a thin wrapper.

In preparation for using the file based interface from io_uring.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Link: https://patch.msgid.link/20260514140817.623026-4-axboe@kernel.dk
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Jens Axboe 2026-05-14 08:07:19 -06:00 committed by Christian Brauner
parent 5de2759f2b
commit 0995baf261
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
2 changed files with 39 additions and 30 deletions
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62
fs/eventpoll.c
View File

@ -99,11 +99,6 @@
#define EP_ITEM_COST (sizeof(struct epitem) + sizeof(struct eppoll_entry))
struct epoll_filefd {
struct file *file;
int fd;
} __packed;
/* Wait structure used by the poll hooks */
struct eppoll_entry {
/* List header used to link this structure to the "struct epitem" */
@ -2225,30 +2220,17 @@ static inline int epoll_mutex_lock(struct mutex *mutex, int depth,
return -EAGAIN;
}
int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
bool nonblock)
int do_epoll_ctl_file(struct file *f, int op, struct epoll_filefd *tf,
struct epoll_event *epds, bool nonblock)
{
int error;
int full_check = 0;
struct eventpoll *ep;
struct epitem *epi;
struct eventpoll *tep = NULL;
struct epoll_filefd efd;
CLASS(fd, f)(epfd);
if (fd_empty(f))
return -EBADF;
/* Get the "struct file *" for the target file */
CLASS(fd, tf)(fd);
if (fd_empty(tf))
return -EBADF;
efd.file = fd_file(tf);
efd.fd = fd;
/* The target file descriptor must support poll */
if (!file_can_poll(fd_file(tf)))
if (!file_can_poll(tf->file))
return -EPERM;
/* Check if EPOLLWAKEUP is allowed */
@ -2261,7 +2243,7 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
* adding an epoll file descriptor inside itself.
*/
error = -EINVAL;
if (fd_file(f) == fd_file(tf) || !is_file_epoll(fd_file(f)))
if (f == tf->file || !is_file_epoll(f))
goto error_tgt_fput;
/*
@ -2272,7 +2254,7 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
if (ep_op_has_event(op) && (epds->events & EPOLLEXCLUSIVE)) {
if (op == EPOLL_CTL_MOD)
goto error_tgt_fput;
if (op == EPOLL_CTL_ADD && (is_file_epoll(fd_file(tf)) ||
if (op == EPOLL_CTL_ADD && (is_file_epoll(tf->file) ||
(epds->events & ~EPOLLEXCLUSIVE_OK_BITS)))
goto error_tgt_fput;
}
@ -2281,7 +2263,7 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
* At this point it is safe to assume that the "private_data" contains
* our own data structure.
*/
ep = fd_file(f)->private_data;
ep = f->private_data;
/*
* When we insert an epoll file descriptor inside another epoll file
@ -2302,16 +2284,16 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
if (error)
goto error_tgt_fput;
if (op == EPOLL_CTL_ADD) {
if (READ_ONCE(fd_file(f)->f_ep) || ep->gen == loop_check_gen ||
is_file_epoll(fd_file(tf))) {
if (READ_ONCE(f->f_ep) || ep->gen == loop_check_gen ||
is_file_epoll(tf->file)) {
mutex_unlock(&ep->mtx);
error = epoll_mutex_lock(&epnested_mutex, 0, nonblock);
if (error)
goto error_tgt_fput;
loop_check_gen++;
full_check = 1;
if (is_file_epoll(fd_file(tf))) {
tep = fd_file(tf)->private_data;
if (is_file_epoll(tf->file)) {
tep = tf->file->private_data;
error = -ELOOP;
if (ep_loop_check(ep, tep) != 0)
goto error_tgt_fput;
@ -2327,14 +2309,14 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
* above, we can be sure to be able to use the item looked up by
* ep_find() till we release the mutex.
*/
epi = ep_find(ep, &efd);
epi = ep_find(ep, tf);
error = -EINVAL;
switch (op) {
case EPOLL_CTL_ADD:
if (!epi) {
epds->events |= EPOLLERR | EPOLLHUP;
error = ep_insert(ep, epds, &efd, full_check);
error = ep_insert(ep, epds, tf, full_check);
} else
error = -EEXIST;
break;
@ -2369,6 +2351,26 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
mutex_unlock(&epnested_mutex);
}
return error;
}
int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
bool nonblock)
{
struct epoll_filefd efd;
CLASS(fd, f)(epfd);
if (fd_empty(f))
return -EBADF;
/* Get the "struct file *" for the target file */
CLASS(fd, tf)(fd);
if (fd_empty(tf))
return -EBADF;
efd.file = fd_file(tf);
efd.fd = fd;
return do_epoll_ctl_file(fd_file(f), op, &efd, epds, nonblock);
}
/*

7
include/linux/eventpoll.h
View File

@ -61,6 +61,13 @@ static inline void eventpoll_release(struct file *file)
eventpoll_release_file(file);
}
struct epoll_filefd {
struct file *file;
int fd;
} __packed;
int do_epoll_ctl_file(struct file *f, int op, struct epoll_filefd *tf,
struct epoll_event *epds, bool nonblock);
int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
bool nonblock);
int is_file_epoll(struct file *f);