tags fixed-upstrream thanks I applied the following patch upstream.
diff --git a/man2/timerfd_create.2 b/man2/timerfd_create.2 index ec137fbfe..98225dcad 100644 --- a/man2/timerfd_create.2 +++ b/man2/timerfd_create.2 @@ -477,6 +477,9 @@ is not a valid timerfd file descriptor. .BR timerfd_settime () can also fail with the following errors: .TP +.B ECANCELED +See NOTES. +.TP .B EINVAL .I new_value is not properly initialized (one of the @@ -493,6 +496,52 @@ These system calls are available on Linux since kernel 2.6. 25. Library support is provided by glibc since version 2.8. .SH CONFORMING TO These system calls are Linux-specific. +.SH NOTES +Suppose the following scenario for +.BR CLOCK_REALTIME +or +.BR CLOCK_REALTIME_ALARM +timer that was created with +.BR timerfd_create (): +.IP (a) 4 +The timer has been started +.RB ( timerfd_settime ()) +with the +.BR TFD_TIMER_ABSTIME +and +.BR TFD_TIMER_CANCEL_ON_SET +flags; +.IP (b) +A discontinuous change (e.g. +.BR settimeofday (2)) +is subsequently made to the +.BR CLOCK_REALTIME +clock; and +.IP (c) +the caller once more calls +.BR timerfd_settime () +to rearm the timer (without first doing a +.BR read (2) +on the file descriptor). +.PP +In this case the following occurs: +.IP \(bu 2 +The +.BR timerfd_settime () +returns \-1 with +.I errno +set to +.BR ECANCELED . +(This enables the caller to know that the previous timer was affected +by a discontinuous change to the clock.) +.IP \(bu +The timer +.I "is successfully rearmed" +with the settings provided in the second +.BR timerfd_settime () +call. +(This was probably an implementation accident, but won't be fixed now, +in case there are applications that depend on this behaviour.) .SH BUGS Currently, .\" 2.6.29
