From 681a1b752c779238688336f219a241567e00decd Mon Sep 17 00:00:00 2001
From: Mateusz Guzik <mjg@FreeBSD.org>
Date: Tue, 20 Feb 2018 10:52:07 +0000
Subject: [PATCH] Make killpg1 perform process validity checks without proc
 lock held.

---
 sys/kern/kern_sig.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index a71de7a5848f..4da8bdf3a300 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -1677,12 +1677,11 @@ killpg1(struct thread *td, int sig, int pgid, int all, ksiginfo_t *ksi)
 		 */
 		sx_slock(&allproc_lock);
 		FOREACH_PROC_IN_SYSTEM(p) {
-			PROC_LOCK(p);
 			if (p->p_pid <= 1 || p->p_flag & P_SYSTEM ||
 			    p == td->td_proc || p->p_state == PRS_NEW) {
-				PROC_UNLOCK(p);
 				continue;
 			}
+			PROC_LOCK(p);
 			err = p_cansignal(td, p, sig);
 			if (err == 0) {
 				if (sig)