From 0676a140b265380e3cf75aef151e68e2108711c5 Mon Sep 17 00:00:00 2001
From: Alan Cox <alc@FreeBSD.org>
Date: Wed, 29 Oct 2003 07:51:41 +0000
Subject: [PATCH]  - Synchronize updates to nswapdev using sw_dev_mtx.

---
 sys/vm/swap_pager.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c
index a7edae2221b..ea697ca2bc5 100644
--- a/sys/vm/swap_pager.c
+++ b/sys/vm/swap_pager.c
@@ -2173,8 +2173,8 @@ swaponsomething(struct vnode *vp, void *id, u_long nblks, sw_strategy_t *strateg
 	sp->sw_first = dvbase;
 	sp->sw_end = dvbase + nblks;
 	TAILQ_INSERT_TAIL(&swtailq, sp, sw_list);
-	mtx_unlock(&sw_dev_mtx);
 	nswapdev++;
+	mtx_unlock(&sw_dev_mtx);
 	swap_pager_avail += nblks;
 	swap_pager_full = 0;
 }
@@ -2277,10 +2277,10 @@ found:
 	sp->sw_id = NULL;
 	mtx_lock(&sw_dev_mtx);
 	TAILQ_REMOVE(&swtailq, sp, sw_list);
+	nswapdev--;
 	mtx_unlock(&sw_dev_mtx);
 	if (swdevhd == sp)
 		swdevhd = NULL;
-	nswapdev--;
 	blist_destroy(sp->sw_blist);
 	free(sp, M_VMPGDATA);