[PATCH 1/3] docs: sysctl/kernel: document cad_pid

[Stephen Kitt]

Based on the implementation in kernel/sysctl.c (the proc_do_cad_pid()
function), kernel/reboot.c, and include/linux/sched/signal.h.

Signed-off-by: Stephen Kitt <steve@xxxxxxx>
---
 Documentation/admin-guide/sysctl/kernel.rst | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 55b24eada13c..82bfd5892663 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -116,6 +116,16 @@ run. The statistics can be seen using ``bpftool``.
 = ===================================
 
 
+cad_pid
+=======
+
+This is the pid which will be signalled on reboot (notably, by
+Ctrl-Alt-Delete). Writing a value to this file which doesn't
+correspond to a running process will result in ``-ESRCH``.
+
+See also `ctrl-alt-del`_.
+
+
 cap_last_cap
 ============
 

base-commit: 7b9121040d83eb9e332f7dbc140eca17643d3586
-- 
2.20.1