From 3582e10e42fed7a08b5cf1ce0b470723428b1386 Mon Sep 17 00:00:00 2001
From: Joe Lawrence <joe.lawrence@redhat.com>
Date: Wed, 15 Nov 2017 10:44:42 -0500
Subject: [PATCH] kpatch: signal stalled processes

Add a "signal" command line option that iterates over all processes that
may be holding up the current livepatch transition.  Send such processes
a SIGSTOP / SIGCONT combination to try and expedite the transition.

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
 kpatch/kpatch | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/kpatch/kpatch b/kpatch/kpatch
index 50783b8..303c67a 100755
--- a/kpatch/kpatch
+++ b/kpatch/kpatch
@@ -49,6 +49,8 @@ usage () {
 	echo >&2
 	usage_cmd "list" "list installed patch modules"
 	echo >&2
+	usage_cmd "signal" "signal/poke any process stalling the current patch transition"
+	echo >&2
 	usage_cmd "version" "display the kpatch version"
 	exit 1
 }
@@ -212,6 +214,33 @@ show_stalled_processes() {
 	done
 }
 
+signal_stalled_processes() {
+	local module
+	local proc_task
+	local tid
+
+	module=$(get_transition_patch)
+	[[ -z "$module" ]] && return
+
+	if [[ -e "/sys/kernel/livepatch/$module/signal" ]] ; then
+		echo 1 > "/sys/kernel/livepatch/$module/signal"
+	else
+		for proc_task in /proc/[0-9]*/task/[0-9]*; do
+			tid=${proc_task#*/task/}
+			if is_stalled "$module" "$tid" ; then
+				if [[ "$tid" -eq "$$" ]] ; then
+					echo "skipping pid $tid $(cat "$proc_task"/comm 2>/dev/null)"
+				else
+					echo "signaling pid $tid $(cat "$proc_task"/comm 2>/dev/null)"
+					kill -SIGSTOP "$tid"
+					sleep .1
+					kill -SIGCONT "$tid"
+				fi
+			fi
+		done
+	fi
+}
+
 load_module () {
 	local module="$1"
 
@@ -442,6 +471,11 @@ case "$1" in
 	modinfo "$MODULE" || die "failed to get info for module $PATCH"
 	;;
 
+"signal")
+	[[ "$#" -ne 1 ]] && usage
+	signal_stalled_processes
+	;;
+
 "help"|"-h"|"--help")
 	usage
 	;;