Fix a bug introduced in revision 222537.

In msgbuf_reinit() and msgbuf_init(), we weren't initializing the mutex.
Depending on the contents of memory, the LO_INITIALIZED flag might be
set on the mutex (either due to a warm reboot, and the message buffer
remaining in place, or due to garbage in memory) and in that case, with
INVARIANTS turned on, we would trigger an assertion that the mutex had
already been initialized.

Fix this by bzeroing the message buffer mutex for the _init() and _reinit()
paths.

Reported by:	mdf

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/kern/subr_msgbuf.c b/sys/kern/subr_msgbuf.c
index c146ab0..cd9c551 100644
--- a/sys/kern/subr_msgbuf.c
+++ b/sys/kern/subr_msgbuf.c
@@ -61,6 +61,7 @@ msgbuf_init(struct msgbuf *mbp, void *ptr, int size)
 	mbp->msg_magic = MSG_MAGIC;
 	mbp->msg_lastpri = -1;
 	mbp->msg_needsnl = 0;
+	bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
 	mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
 }
 
@@ -95,6 +96,7 @@ msgbuf_reinit(struct msgbuf *mbp, void *ptr, int size)
 	mbp->msg_lastpri = -1;
 	/* Assume that the old message buffer didn't end in a newline. */
 	mbp->msg_needsnl = 1;
+	bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
 	mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
 }