Messages in this thread | | | Date | Sat, 24 Sep 2005 06:05:34 +0200 | From | Willy Tarreau <> | Subject | Re: [patch] sys_epoll_wait() timeout saga ... |
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Hi Davide,
On Fri, Sep 23, 2005 at 11:13:30AM -0700, Davide Libenzi wrote: > > The sys_epoll_wait() function was not handling correctly negative > timeouts (besides -1), and like sys_poll(), was comparing millisec to > secs in testing the upper timeout limit. > > > Signed-off-by: Davide Libenzi <davidel@xmailserver.org> > > > - Davide
> --- a/fs/eventpoll.c 2005-09-23 10:56:57.000000000 -0700 > +++ b/fs/eventpoll.c 2005-09-23 11:00:06.000000000 -0700 > @@ -1507,7 +1507,7 @@ > * and the overflow condition. The passed timeout is in milliseconds, > * that why (t * HZ) / 1000. > */ > - jtimeout = timeout == -1 || timeout > (MAX_SCHEDULE_TIMEOUT - 1000) / HZ ? > + jtimeout = timeout < 0 || (timeout / 1000) >= (MAX_SCHEDULE_TIMEOUT / HZ) ? > MAX_SCHEDULE_TIMEOUT: (timeout * HZ + 999) / 1000;
Here, I'm not certain that gcc will optimize the divide. It would be better anyway to write this which is equivalent, and a pure integer comparison :
+ jtimeout = timeout < 0 || timeout >= 1000 * MAX_SCHEDULE_TIMEOUT / HZ ? > MAX_SCHEDULE_TIMEOUT: (timeout * HZ + 999) / 1000;
gcc will also spit a warning if the constant is too big for an int, depending on MAX_SCHEDULE_TIMEOUT and HZ, while in the previous case, it would remain silent, and possibly, timeout/1000 would never reach the limit.
Regards, Willy
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