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UPSTREAM: epoll: convert internal api to timespec64

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Patch series "add epoll_pwait2 syscall", v4.

Enable nanosecond timeouts for epoll.

Analogous to pselect and ppoll, introduce an epoll_wait syscall
variant that takes a struct timespec instead of int timeout.

This patch (of 4):

Make epoll more consistent with select/poll: pass along the timeout as
timespec64 pointer.

In anticipation of additional changes affecting all three polling
mechanisms:

- add epoll_pwait2 syscall with timespec semantics,
  and share poll_select_set_timeout implementation.
- compute slack before conversion to absolute time,
  to save one ktime_get_ts64 call.

Link: https://lkml.kernel.org/r/20201121144401.3727659-1-willemdebruijn.kernel@gmail.com
Link: https://lkml.kernel.org/r/20201121144401.3727659-2-willemdebruijn.kernel@gmail.com
Change-Id: Id5851ad620849d202d18a99351a98b8bc3b6820a
Signed-off-by: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Willem de Bruijn 2020-12-18 14:05:35 -08:00 • committed by Michael Bestas
commit 4889a679d0
No known key found for this signature in database
GPG key ID: CC95044519BE6669
1 changed files with 37 additions and 20 deletions
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57
fs/eventpoll.c
View file

@ -1796,15 +1796,25 @@ static int ep_send_events(struct eventpoll *ep,
return esed.res;
}
static inline struct timespec64 ep_set_mstimeout(long ms)
static struct timespec64 *ep_timeout_to_timespec(struct timespec64 *to, long ms)
{
struct timespec64 now, ts = {
.tv_sec = ms / MSEC_PER_SEC,
.tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC),
};
struct timespec64 now;
if (ms < 0)
return NULL;
if (!ms) {
to->tv_sec = 0;
to->tv_nsec = 0;
return to;
}
to->tv_sec = ms / MSEC_PER_SEC;
to->tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC);
ktime_get_ts64(&now);
return timespec64_add_safe(now, ts);
*to = timespec64_add_safe(now, *to);
return to;
}
/*
@ -1835,8 +1845,8 @@ static int ep_autoremove_wake_function(struct wait_queue_entry *wq_entry,
* stored.
* @maxevents: Size (in terms of number of events) of the caller event buffer.
* @timeout: Maximum timeout for the ready events fetch operation, in
* milliseconds. If the @timeout is zero, the function will not block,
* while if the @timeout is less than zero, the function will block
* timespec. If the timeout is zero, the function will not block,
* while if the @timeout ptr is NULL, the function will block
* until at least one event has been retrieved (or an error
* occurred).
*
@ -1844,7 +1854,7 @@ static int ep_autoremove_wake_function(struct wait_queue_entry *wq_entry,
* error code, in case of error.
*/
static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
int maxevents, long timeout)
int maxevents, struct timespec64 *timeout)
{
int res = 0, eavail, timed_out = 0;
u64 slack = 0;
@ -1853,13 +1863,11 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
lockdep_assert_irqs_enabled();
if (timeout > 0) {
struct timespec64 end_time = ep_set_mstimeout(timeout);
slack = select_estimate_accuracy(&end_time);
if (timeout && (timeout->tv_sec | timeout->tv_nsec)) {
slack = select_estimate_accuracy(timeout);
to = &expires;
*to = timespec64_to_ktime(end_time);
} else if (timeout == 0) {
*to = timespec64_to_ktime(*timeout);
} else if (timeout) {
/*
* Avoid the unnecessary trip to the wait queue loop, if the
* caller specified a non blocking operation. We still need
@ -2298,7 +2306,7 @@ error_return:
* part of the user space epoll_wait(2).
*/
static int do_epoll_wait(int epfd, struct epoll_event __user *events,
int maxevents, int timeout)
int maxevents, struct timespec64 *to)
{
int error;
struct fd f;
@ -2332,7 +2340,7 @@ static int do_epoll_wait(int epfd, struct epoll_event __user *events,
ep = f.file->private_data;
/* Time to fish for events ... */
error = ep_poll(ep, events, maxevents, timeout);
error = ep_poll(ep, events, maxevents, to);
error_fput:
fdput(f);
@ -2342,7 +2350,10 @@ error_fput:
SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
int, maxevents, int, timeout)
{
return do_epoll_wait(epfd, events, maxevents, timeout);
struct timespec64 to;
return do_epoll_wait(epfd, events, maxevents,
ep_timeout_to_timespec(&to, timeout));
}
/*
@ -2353,6 +2364,7 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
int, maxevents, int, timeout, const sigset_t __user *, sigmask,
size_t, sigsetsize)
{
struct timespec64 to;
int error;
/*
@ -2363,7 +2375,9 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
if (error)
return error;
error = do_epoll_wait(epfd, events, maxevents, timeout);
error = do_epoll_wait(epfd, events, maxevents,
ep_timeout_to_timespec(&to, timeout));
restore_saved_sigmask_unless(error == -EINTR);
return error;
@ -2376,6 +2390,7 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
const compat_sigset_t __user *, sigmask,
compat_size_t, sigsetsize)
{
struct timespec64 to;
long err;
/*
@ -2386,7 +2401,9 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
if (err)
return err;
err = do_epoll_wait(epfd, events, maxevents, timeout);
err = do_epoll_wait(epfd, events, maxevents,
ep_timeout_to_timespec(&to, timeout));
restore_saved_sigmask_unless(err == -EINTR);
return err;