From: Simon Schubert <corecode@dragonflybsd.org>
Date: Sat, 7 Mar 2009 16:35:02 +0000 (+0100)
Subject: signals: stop all threads of a process before taking a checkpoint
X-Git-Tag: v2.3.1~311
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/6acb4ed8e75e72485a7d174d6366a227b1879805

signals: stop all threads of a process before taking a checkpoint

If we want to checkpoint a multi-threaded process, we need to wait until
the process is in a quiescent state, otherwise our checkpoint might be
incorrect.
---

diff --git a/sys/kern/kern_checkpoint.c b/sys/kern/kern_checkpoint.c
index 470cd5ac5a..38324643d7 100644
--- a/sys/kern/kern_checkpoint.c
+++ b/sys/kern/kern_checkpoint.c
@@ -693,7 +693,11 @@ ckpt_freeze_proc(struct lwp *lp, struct file *fp)
         PRINTF(("calling generic_elf_coredump\n"));
 	limit = p->p_rlimit[RLIMIT_CORE].rlim_cur;
 	if (limit) {
+		proc_stop(p);
+		while (p->p_nstopped < p->p_nthreads - 1)
+			tsleep(&p->p_nstopped, 0, "freeze", 1);
 		error = generic_elf_coredump(lp, SIGCKPT, fp, limit);
+		proc_unstop(p);
 	} else {
 		error = ERANGE;
 	}