In kernel/sys.c, arg2 is an unsigned long value and it will never less than 0. Also, since kernel commit id da8b44d5a9f8, timer_slack_ns and default timer_slack_ns have been converted into u64, the return value of PR_GET_TIMERSLACK has been limited under ULONG_MAX. The timer slack value also can be inherited by a child created via fork(2). Signed-off-by: Yang Xu <xuyang2018.jy@xxxxxxxxxxxxxx> --- man2/prctl.2 | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/man2/prctl.2 b/man2/prctl.2 index 52fd0f3f3..348a39f6a 100644 --- a/man2/prctl.2 +++ b/man2/prctl.2 @@ -1239,14 +1239,15 @@ this operation expects a user-space buffer of 8 (not 4) bytes on these ABIs. Each thread has two associated timer slack values: a "default" value, and a "current" value. This operation sets the "current" timer slack value for the calling thread. +.I arg2 +is an unsigned long value, then maximum "current" value is ULONG_MAX and +the minimum "current" value is 1. If the nanosecond value supplied in .IR arg2 is greater than zero, then the "current" value is set to this value. If .I arg2 -is less than or equal to zero, -.\" It seems that it's not possible to set the timer slack to zero; -.\" The minimum value is 1? Seems a little strange. +is equal to zero, the "current" timer slack is reset to the thread's "default" timer slack value. .IP @@ -1291,7 +1292,9 @@ The timer slack values of .IR init (PID 1), the ancestor of all processes, are 50,000 nanoseconds (50 microseconds). -The timer slack values are preserved across +The timer slack value is inherited by a child created via +.BR fork(2), +and is preserved across .BR execve (2). .IP Since Linux 4.6, the "current" timer slack value of any process -- 2.18.1
