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Subject[PATCH v4 2/4] epoll: add syscall epoll_pwait2
Date
From: Willem de Bruijn <willemb@google.com>

Add syscall epoll_pwait2, an epoll_wait variant with nsec resolution
that replaces int timeout with struct timespec. It is equivalent
otherwise.

int epoll_pwait2(int fd, struct epoll_event *events,
int maxevents,
const struct timespec *timeout,
const sigset_t *sigset);

The underlying hrtimer is already programmed with nsec resolution.
pselect and ppoll also set nsec resolution timeout with timespec.

The sigset_t in epoll_pwait has a compat variant. epoll_pwait2 needs
the same.

For timespec, only support this new interface on 2038 aware platforms
that define __kernel_timespec_t. So no CONFIG_COMPAT_32BIT_TIME.

Changes
v4:
- on top of patch that converts eventpoll.c to pass timespec64
- split off wiring up the syscall
- fix alpha syscall number (Arnd)
v3:
- rewrite: add epoll_pwait2 syscall instead of epoll_create1 flag
v2:
- cast to s64: avoid overflow on 32-bit platforms (Shuo Chen)
- minor commit message rewording

Signed-off-by: Willem de Bruijn <willemb@google.com>
---
fs/eventpoll.c | 87 ++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 73 insertions(+), 14 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 7082dfbc3166..c6d0ab3aaff1 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -2239,11 +2239,10 @@ SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
* Implement the event wait interface for the eventpoll file. It is the kernel
* part of the user space epoll_pwait(2).
*/
-SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
- int, maxevents, int, timeout, const sigset_t __user *, sigmask,
- size_t, sigsetsize)
+static int do_epoll_pwait(int epfd, struct epoll_event __user *events,
+ int maxevents, struct timespec64 *to,
+ const sigset_t __user *sigmask, size_t sigsetsize)
{
- struct timespec64 to;
int error;

/*
@@ -2254,22 +2253,48 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
if (error)
return error;

- error = do_epoll_wait(epfd, events, maxevents,
- ep_timeout_to_timespec(&to, timeout));
+ error = do_epoll_wait(epfd, events, maxevents, to);

restore_saved_sigmask_unless(error == -EINTR);

return error;
}

-#ifdef CONFIG_COMPAT
-COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
- struct epoll_event __user *, events,
- int, maxevents, int, timeout,
- const compat_sigset_t __user *, sigmask,
- compat_size_t, sigsetsize)
+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;
+
+ return do_epoll_pwait(epfd, events, maxevents,
+ ep_timeout_to_timespec(&to, timeout),
+ sigmask, sigsetsize);
+}
+
+SYSCALL_DEFINE6(epoll_pwait2, int, epfd, struct epoll_event __user *, events,
+ int, maxevents, const struct __kernel_timespec __user *, timeout,
+ const sigset_t __user *, sigmask, size_t, sigsetsize)
+{
+ struct timespec64 ts, *to = NULL;
+
+ if (timeout) {
+ if (get_timespec64(&ts, timeout))
+ return -EFAULT;
+ to = &ts;
+ if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
+ return -EINVAL;
+ }
+
+ return do_epoll_pwait(epfd, events, maxevents, to,
+ sigmask, sigsetsize);
+}
+
+#ifdef CONFIG_COMPAT
+static int do_compat_epoll_pwait(int epfd, struct epoll_event __user *events,
+ int maxevents, struct timespec64 *timeout,
+ const compat_sigset_t __user *sigmask,
+ compat_size_t sigsetsize)
+{
long err;

/*
@@ -2280,13 +2305,47 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
if (err)
return err;

- err = do_epoll_wait(epfd, events, maxevents,
- ep_timeout_to_timespec(&to, timeout));
+ err = do_epoll_wait(epfd, events, maxevents, timeout);

restore_saved_sigmask_unless(err == -EINTR);

return err;
}
+
+COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
+ struct epoll_event __user *, events,
+ int, maxevents, int, timeout,
+ const compat_sigset_t __user *, sigmask,
+ compat_size_t, sigsetsize)
+{
+ struct timespec64 to;
+
+ return do_compat_epoll_pwait(epfd, events, maxevents,
+ ep_timeout_to_timespec(&to, timeout),
+ sigmask, sigsetsize);
+}
+
+COMPAT_SYSCALL_DEFINE6(epoll_pwait2, int, epfd,
+ struct epoll_event __user *, events,
+ int, maxevents,
+ const struct __kernel_timespec __user *, timeout,
+ const compat_sigset_t __user *, sigmask,
+ compat_size_t, sigsetsize)
+{
+ struct timespec64 ts, *to = NULL;
+
+ if (timeout) {
+ if (get_timespec64(&ts, timeout))
+ return -EFAULT;
+ to = &ts;
+ if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
+ return -EINVAL;
+ }
+
+ return do_compat_epoll_pwait(epfd, events, maxevents, to,
+ sigmask, sigsetsize);
+}
+
#endif

static int __init eventpoll_init(void)
--
2.29.2.454.gaff20da3a2-goog
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