lkml.org 
[lkml]   [2020]   [Nov]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v4 1/4] epoll: convert internal api to timespec64
Date
From: Willem de Bruijn <willemb@google.com>

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.

Signed-off-by: Willem de Bruijn <willemb@google.com>
---
fs/eventpoll.c | 57 ++++++++++++++++++++++++++++++++------------------
1 file changed, 37 insertions(+), 20 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 297aeb0ee9d1..7082dfbc3166 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1714,15 +1714,25 @@ static int ep_send_events(struct eventpoll *ep,
return 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;
}

/**
@@ -1734,8 +1744,8 @@ 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).
*
@@ -1743,7 +1753,7 @@ 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, eavail, timed_out = 0;
u64 slack = 0;
@@ -1752,13 +1762,11 @@ 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.
@@ -2177,7 +2185,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
* 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;
@@ -2211,7 +2219,7 @@ 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);
@@ -2221,7 +2229,10 @@ static int do_epoll_wait(int epfd, struct epoll_event __user *events,
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));
}

/*
@@ -2232,6 +2243,7 @@ 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;

/*
@@ -2242,7 +2254,9 @@ 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;
@@ -2255,6 +2269,7 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
const compat_sigset_t __user *, sigmask,
compat_size_t, sigsetsize)
{
+ struct timespec64 to;
long err;

/*
@@ -2265,7 +2280,9 @@ 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;
--
2.29.2.454.gaff20da3a2-goog
\
 
 \ /
  Last update: 2020-11-21 15:46    [W:0.040 / U:0.164 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site