From 45726c1dae2081b18b00c6698ca1fd3949d80133 Mon Sep 17 00:00:00 2001
From: John Baldwin <jhb@FreeBSD.org>
Date: Tue, 24 Apr 2018 05:42:10 +0000
Subject: [PATCH] Relock PROC_LOCK before one failure case in
 ptrace_single_step().

The MIPS ptrace_single_step() unlocks the PROC_LOCK while reading and
writing instructions from userland.  One failure case was not reacquiring
the lock before returning.
---
 sys/mips/mips/pm_machdep.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sys/mips/mips/pm_machdep.c b/sys/mips/mips/pm_machdep.c
index d4571bb634e2..6477135b073e 100644
--- a/sys/mips/mips/pm_machdep.c
+++ b/sys/mips/mips/pm_machdep.c
@@ -260,6 +260,7 @@ ptrace_single_step(struct thread *td)
 	if (td->td_md.md_ss_addr) {
 		printf("SS %s (%d): breakpoint already set at %x (va %x)\n",
 		    p->p_comm, p->p_pid, td->td_md.md_ss_addr, va); /* XXX */
+		PROC_LOCK(p);
 		return (EFAULT);
 	}
 	td->td_md.md_ss_addr = va;