From: Christian Brauner <christian@xxxxxxxxxx>
Add an entry for CLONE_PIDFD. This flag is available starting with
kernel 5.2. If specified, a process file descriptor ("pidfd") referring
to the child process will be returned in the ptid argument.
Signed-off-by: Christian Brauner <christian@xxxxxxxxxx>
---
man2/clone.2 | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)
diff --git a/man2/clone.2 b/man2/clone.2
index 7e880beb8..ee08aeb42 100644
--- a/man2/clone.2
+++ b/man2/clone.2
@@ -539,6 +539,42 @@ The flag disappeared completely from the kernel sources in Linux 2.5.16.
Since then, the kernel silently ignores this bit if it is specified in
.IR flags .
.TP
+.BR CLONE_PIDFD " (since Linux 5.2)"
+If
+.B CLONE_PIDFD
+is set,
+.BR clone ()
+stores a process file descriptor ("pidfd") referring to the child process at
+the location
+.I ptid
+in the parent's memory. Note, that the kernel verifies that the value for
+.I ptid
+is zero. If it is not an error will be returned. This ensures that
+.I ptid
+can potentially be used to specify additional options for
+.B CLONE_PIDFD
+in the future.
+.IP
+Since the
+.I ptid
+argument is used to return the pidfd,
+.B CLONE_PIDFD
+cannot be used with
+.B CLONE_PARENT_SETTID.
+.IP
+It is currently not possible to use this flag together with
+.B CLONE_THREAD.
+This means that the process identified by the pidfd will always be a
+thread-group leader.
+.IP
+For a while there was a
+.B CLONE_DETACHED
+flag. This flag is usually ignored when passed along with other flags.
+However, when passed alongside
+.B CLONE_PIDFD
+an error will be returned. This ensures that this flag can be reused
+for further pidfd features in the future.
+.TP
.BR CLONE_PTRACE " (since Linux 2.2)"
If
.B CLONE_PTRACE
@@ -1122,6 +1158,21 @@ For example, on aarch64,
.I child_stack
must be a multiple of 16.
.TP
+.B EINVAL
+.B CLONE_PIDFD
+was specified together with
+.B CLONE_DETACHED.
+.TP
+.B EINVAL
+.B CLONE_PIDFD
+was specified together with
+.B CLONE_PARENT_SETTID.
+.TP
+.B EINVAL
+.B CLONE_PIDFD
+was specified together with
+.B CLONE_THREAD.
+.TP
.B ENOMEM
Cannot allocate sufficient memory to allocate a task structure for the
child, or to copy those parts of the caller's context that need to be
--
2.21.0
