If we pass "-1" to arg2, PR_SET_TIMERSLACK will set ULONG_MAX to timer slack_ns
instead of using default value. Also, after kernel commit da8b44d5a9f8 ("timer:
convert timer_slack_ns from unsigned long to u64"), 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.
Signed-off-by: Yang Xu <xuyang2018.jy@xxxxxxxxxxxxxx>
---
man2/prctl.2 | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/man2/prctl.2 b/man2/prctl.2
index 52fd0f3f3..de6a34c68 100644
--- a/man2/prctl.2
+++ b/man2/prctl.2
@@ -1239,12 +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.
+.IR arg2
+is an unsigned long value.
If the nanosecond value supplied in
.IR arg2
is greater than zero, then the "current" value is set to this value.
+The maximum "current" value is ULONG_MAX.
If
.I arg2
-is less than or equal to zero,
+is 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.
the "current" timer slack is reset to the
@@ -1303,6 +1306,7 @@ See
.BR PR_GET_TIMERSLACK " (since Linux 2.6.28)"
Return (as the function result)
the "current" timer slack value of the calling thread.
+The maximum value is ULONG_MAX.
.TP
.BR PR_SET_TIMING " (since Linux 2.6.0)"
.\" Precisely: Linux 2.6.0-test4
--
2.18.1
