[PATCH RFC v3 1/7] epoll: Extract epoll_wait_do and epoll_pwait_do

Fam Zheng
2015-02-13T09:05:38Z

In preparation of new epoll syscalls, this patch allows reusing the code from
epoll_pwait implementation. The new functions uses ktime_t for more accuracy.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
fs/eventpoll.c | 162 ++++++++++++++++++++++++++-------------------------------
1 file changed, 75 insertions(+), 87 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index d77f944..4cf359d 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1554,17 +1554,6 @@ static int ep_send_events(struct eventpoll *ep,
return ep_scan_ready_list(ep, ep_send_events_proc, &esed, 0, false);
}

-static inline struct timespec ep_set_mstimeout(long ms)
-{
- struct timespec now, ts = {
- .tv_sec = ms / MSEC_PER_SEC,
- .tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC),
- };
-
- ktime_get_ts(&now);
- return timespec_add_safe(now, ts);
-}
-
/**
* ep_poll - Retrieves ready events, and delivers them to the caller supplied
* event buffer.
@@ -1573,17 +1562,15 @@ static inline struct timespec ep_set_mstimeout(long ms)
* @events: Pointer to the userspace buffer where the ready events should be
* 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
- * until at least one event has been retrieved (or an error
- * occurred).
+ * @timeout: Maximum timeout for the ready events fetch operation. If 0, the
+ * function will not block. If negative, the function will block until
+ * at least one event has been retrieved (or an error occurred).
*
* Returns: Returns the number of ready events which have been fetched, or an
* error code, in case of error.
*/
static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
- int maxevents, long timeout)
+ int maxevents, const ktime_t timeout)
{
int res = 0, eavail, timed_out = 0;
unsigned long flags;
@@ -1591,13 +1578,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
wait_queue_t wait;
ktime_t expires, *to = NULL;

- if (timeout > 0) {
- struct timespec end_time = ep_set_mstimeout(timeout);
-
- slack = select_estimate_accuracy(&end_time);
- to = &expires;
- *to = timespec_to_ktime(end_time);
- } else if (timeout == 0) {
+ if (!ktime_to_ns(timeout)) {
/*
* Avoid the unnecessary trip to the wait queue loop, if the
* caller specified a non blocking operation.
@@ -1605,6 +1586,15 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
timed_out = 1;
spin_lock_irqsave(&ep->lock, flags);
goto check_events;
+ } else if (ktime_to_ns(timeout) > 0) {
+ struct timespec now, end_time;
+
+ ktime_get_ts(&now);
+ end_time = timespec_add_safe(now, ktime_to_timespec(timeout));
+
+ slack = select_estimate_accuracy(&end_time);
+ to = &expires;
+ *to = timespec_to_ktime(end_time);
}

fetch_events:
@@ -1954,12 +1944,8 @@ error_return:
return error;
}

-/*
- * Implement the event wait interface for the eventpoll file. It is the kernel
- * part of the user space epoll_wait(2).
- */
-SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
- int, maxevents, int, timeout)
+static inline int epoll_wait_do(int epfd, struct epoll_event __user *events,
+ int maxevents, const ktime_t timeout)
{
int error;
struct fd f;
@@ -2002,91 +1988,93 @@ error_fput:

/*
* Implement the event wait interface for the eventpoll file. It is the kernel
+ * part of the user space epoll_wait(2).
+ */
+SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
+ int, maxevents, int, timeout)
+{
+ ktime_t kt = ms_to_ktime(timeout);
+ return epoll_wait_do(epfd, events, maxevents, kt);
+}
+
+static inline int epoll_pwait_do(int epfd, struct epoll_event __user *events,
+ int maxevents, ktime_t timeout,
+ sigset_t *sigmask, size_t sigsetsize)
+{
+ int error;
+ sigset_t sigsaved;
+
+ /*
+ * If the caller wants a certain signal mask to be set during the wait,
+ * we apply it here.
+ */
+ if (sigmask) {
+ sigsaved = current->blocked;
+ set_current_blocked(sigmask);
+ }
+
+ error = epoll_wait_do(epfd, events, maxevents, timeout);
+
+ /*
+ * If we changed the signal mask, we need to restore the original one.
+ * In case we've got a signal while waiting, we do not restore the
+ * signal mask yet, and we allow do_signal() to deliver the signal on
+ * the way back to userspace, before the signal mask is restored.
+ */
+ if (sigmask) {
+ if (error == -EINTR) {
+ memcpy(&current->saved_sigmask, &sigsaved,
+ sizeof(sigsaved));
+ set_restore_sigmask();
+ } else
+ set_current_blocked(&sigsaved);
+ }
+
+ return error;
+}
+
+/*
+ * 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)
{
- int error;
- sigset_t ksigmask, sigsaved;
+ ktime_t kt = ms_to_ktime(timeout);
+ sigset_t ksigmask;

- /*
- * If the caller wants a certain signal mask to be set during the wait,
- * we apply it here.
- */
if (sigmask) {
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
return -EFAULT;
- sigsaved = current->blocked;
- set_current_blocked(&ksigmask);
}
-
- error = sys_epoll_wait(epfd, events, maxevents, timeout);
-
- /*
- * If we changed the signal mask, we need to restore the original one.
- * In case we've got a signal while waiting, we do not restore the
- * signal mask yet, and we allow do_signal() to deliver the signal on
- * the way back to userspace, before the signal mask is restored.
- */
- if (sigmask) {
- if (error == -EINTR) {
- memcpy(&current->saved_sigmask, &sigsaved,
- sizeof(sigsaved));
- set_restore_sigmask();
- } else
- set_current_blocked(&sigsaved);
- }
-
- return error;
+ return epoll_pwait_do(epfd, events, maxevents, kt,
+ sigmask ? &ksigmask : NULL, sigsetsize);
}

#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)
+ struct epoll_event __user *, events,
+ int, maxevents, int, timeout,
+ const compat_sigset_t __user *, sigmask,
+ compat_size_t, sigsetsize)
{
- long err;
compat_sigset_t csigmask;
- sigset_t ksigmask, sigsaved;
+ sigset_t ksigmask;
+ ktime_t kt = ms_to_ktime(timeout);

- /*
- * If the caller wants a certain signal mask to be set during the wait,
- * we apply it here.
- */
if (sigmask) {
if (sigsetsize != sizeof(compat_sigset_t))
return -EINVAL;
if (copy_from_user(&csigmask, sigmask, sizeof(csigmask)))
return -EFAULT;
sigset_from_compat(&ksigmask, &csigmask);
- sigsaved = current->blocked;
- set_current_blocked(&ksigmask);
}

- err = sys_epoll_wait(epfd, events, maxevents, timeout);
-
- /*
- * If we changed the signal mask, we need to restore the original one.
- * In case we've got a signal while waiting, we do not restore the
- * signal mask yet, and we allow do_signal() to deliver the signal on
- * the way back to userspace, before the signal mask is restored.
- */
- if (sigmask) {
- if (err == -EINTR) {
- memcpy(&current->saved_sigmask, &sigsaved,
- sizeof(sigsaved));
- set_restore_sigmask();
- } else
- set_current_blocked(&sigsaved);
- }
-
- return err;
+ return epoll_pwait_do(epfd, events, maxevents, kt,
+ sigmask ? &ksigmask : NULL, sigsetsize);
}
#endif

--
1.9.3