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BACKPORT: 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 theshaenix
parent 0a6abfc71e
commit 0927c223ca
1 changed files with 35 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

55
fs/eventpoll.c
View File

@@ -1726,15 +1726,25 @@ static int ep_send_events(struct eventpoll *ep,
return ep_scan_ready_list(ep, ep_send_events_proc, &esed, 0, false);
}
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;
}
/**
@@ -1746,8 +1756,8 @@ static inline struct timespec64 ep_set_mstimeout(long ms)
* 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).
*
@@ -1755,7 +1765,7 @@ static inline struct timespec64 ep_set_mstimeout(long ms)
* 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;
unsigned long flags;
@@ -1763,13 +1773,11 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
wait_queue_entry_t wait;
ktime_t expires, *to = NULL;
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.
@@ -2188,7 +2196,7 @@ 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;
@@ -2222,7 +2230,7 @@ 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);
@@ -2232,7 +2240,10 @@ 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));
}
/*
@@ -2243,6 +2254,7 @@ 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;
sigset_t ksigmask, sigsaved;
@@ -2259,7 +2271,8 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
set_current_blocked(&ksigmask);
}
error = do_epoll_wait(epfd, events, maxevents, timeout);
error = do_epoll_wait(epfd, events, maxevents,
ep_timeout_to_timespec(&to, timeout));
/*
* If we changed the signal mask, we need to restore the original one.
@@ -2286,6 +2299,7 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
const compat_sigset_t __user *, sigmask,
compat_size_t, sigsetsize)
{
struct timespec64 to;
long err;
compat_sigset_t csigmask;
sigset_t ksigmask, sigsaved;
@@ -2304,7 +2318,8 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
set_current_blocked(&ksigmask);
}
err = do_epoll_wait(epfd, events, maxevents, timeout);
err = do_epoll_wait(epfd, events, maxevents,
ep_timeout_to_timespec(&to, timeout));
/*
* If we changed the signal mask, we need to restore the original one.