From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Thu, 22 Dec 2011 19:45:06 +0000 (-0800)
Subject: kernel - Reorder critical section interlock in splz()
X-Git-Tag: v3.0.0~323
X-Git-Url: http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/b5fc1882b8093c93638c797f071c8c1d04090026

kernel - Reorder critical section interlock in splz()

* Reorder a critical section interlock in splz() to remove a one-instruction
  window where an interrupt might nest against the splz() operation.
---

diff --git a/sys/platform/pc32/i386/ipl.s b/sys/platform/pc32/i386/ipl.s
index 05bf5a2..01f2324 100644
--- a/sys/platform/pc32/i386/ipl.s
+++ b/sys/platform/pc32/i386/ipl.s
@@ -443,8 +443,8 @@ splz_soft:
 	addl	$FIRST_SOFTINT,%ecx	/* actual intr number */
 	pushl	%eax
 	pushl	%ecx
-	decl	TD_CRITCOUNT(%ebx)
 	incl	TD_NEST_COUNT(%ebx)	/* prevent doreti/splz nesting */
+	decl	TD_CRITCOUNT(%ebx)
 	call	sched_ithd_soft		/* YYY must pull in imasks */
 	incl	TD_CRITCOUNT(%ebx)
 	decl	TD_NEST_COUNT(%ebx)	/* prevent doreti/splz nesting */