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| author | Shawn Bohrer <shawn.bohrer@gmail.com> | 2010-10-27 15:34:54 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-27 18:03:18 -0700 |
| commit | 95aac7b1cd224f568fb83937044cd303ff11b029 (patch) | |
| tree | 24c08cfe031ecc0549cf3f7900e992a27044c4ad /fs | |
| parent | 231f3d393f63f6e3b505afa179999bba491d0f08 (diff) | |
| download | linux-95aac7b1cd224f568fb83937044cd303ff11b029.tar.gz linux-95aac7b1cd224f568fb83937044cd303ff11b029.tar.bz2 linux-95aac7b1cd224f568fb83937044cd303ff11b029.zip | |
epoll: make epoll_wait() use the hrtimer range feature
This make epoll use hrtimers for the timeout value which prevents
epoll_wait() from timing out up to a millisecond early.
This mirrors the behavior of select() and poll().
Signed-off-by: Shawn Bohrer <shawn.bohrer@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/eventpoll.c | 35 | ||||
| -rw-r--r-- | fs/select.c | 2 |
2 files changed, 20 insertions, 17 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 256bb7bb102a..8cf07242067d 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -77,9 +77,6 @@ /* Maximum number of nesting allowed inside epoll sets */ #define EP_MAX_NESTS 4 -/* Maximum msec timeout value storeable in a long int */ -#define EP_MAX_MSTIMEO min(1000ULL * MAX_SCHEDULE_TIMEOUT / HZ, (LONG_MAX - 999ULL) / HZ) - #define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event)) #define EP_UNACTIVE_PTR ((void *) -1L) @@ -1117,18 +1114,22 @@ static int ep_send_events(struct eventpoll *ep, static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, int maxevents, long timeout) { - int res, eavail; + int res, eavail, timed_out = 0; unsigned long flags; - long jtimeout; + long slack; wait_queue_t wait; - - /* - * Calculate the timeout by checking for the "infinite" value (-1) - * and the overflow condition. The passed timeout is in milliseconds, - * that why (t * HZ) / 1000. - */ - jtimeout = (timeout < 0 || timeout >= EP_MAX_MSTIMEO) ? - MAX_SCHEDULE_TIMEOUT : (timeout * HZ + 999) / 1000; + struct timespec end_time; + ktime_t expires, *to = NULL; + + if (timeout > 0) { + ktime_get_ts(&end_time); + timespec_add_ns(&end_time, (u64)timeout * NSEC_PER_MSEC); + slack = select_estimate_accuracy(&end_time); + to = &expires; + *to = timespec_to_ktime(end_time); + } else if (timeout == 0) { + timed_out = 1; + } retry: spin_lock_irqsave(&ep->lock, flags); @@ -1150,7 +1151,7 @@ retry: * to TASK_INTERRUPTIBLE before doing the checks. */ set_current_state(TASK_INTERRUPTIBLE); - if (!list_empty(&ep->rdllist) || !jtimeout) + if (!list_empty(&ep->rdllist) || timed_out) break; if (signal_pending(current)) { res = -EINTR; @@ -1158,7 +1159,9 @@ retry: } spin_unlock_irqrestore(&ep->lock, flags); - jtimeout = schedule_timeout(jtimeout); + if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS)) + timed_out = 1; + spin_lock_irqsave(&ep->lock, flags); } __remove_wait_queue(&ep->wq, &wait); @@ -1176,7 +1179,7 @@ retry: * more luck. */ if (!res && eavail && - !(res = ep_send_events(ep, events, maxevents)) && jtimeout) + !(res = ep_send_events(ep, events, maxevents)) && !timed_out) goto retry; return res; diff --git a/fs/select.c b/fs/select.c index 5f023f911202..b7b10aa30861 100644 --- a/fs/select.c +++ b/fs/select.c @@ -67,7 +67,7 @@ static long __estimate_accuracy(struct timespec *tv) return slack; } -static long select_estimate_accuracy(struct timespec *tv) +long select_estimate_accuracy(struct timespec *tv) { unsigned long ret; struct timespec now; |