Module Name: src
Committed By: mlelstv
Date: Fri Aug 28 05:49:31 UTC 2015
Modified Files:
src/sys/dev: dksubr.c dkvar.h
Log Message:
Prevent race condition where two threads can defer a buffer.
To generate a diff of this commit:
cvs rdiff -u -r1.74 -r1.75 src/sys/dev/dksubr.c
cvs rdiff -u -r1.22 -r1.23 src/sys/dev/dkvar.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/dev/dksubr.c
diff -u src/sys/dev/dksubr.c:1.74 src/sys/dev/dksubr.c:1.75
--- src/sys/dev/dksubr.c:1.74 Thu Aug 27 05:51:50 2015
+++ src/sys/dev/dksubr.c Fri Aug 28 05:49:31 2015
@@ -1,4 +1,4 @@
-/* $NetBSD: dksubr.c,v 1.74 2015/08/27 05:51:50 mlelstv Exp $ */
+/* $NetBSD: dksubr.c,v 1.75 2015/08/28 05:49:31 mlelstv Exp $ */
/*-
* Copyright (c) 1996, 1997, 1998, 1999, 2002, 2008 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: dksubr.c,v 1.74 2015/08/27 05:51:50 mlelstv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: dksubr.c,v 1.75 2015/08/28 05:49:31 mlelstv Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -301,6 +301,10 @@ dk_start(struct dk_softc *dksc, struct b
if (bp != NULL)
bufq_put(dksc->sc_bufq, bp);
+ if (dksc->sc_busy)
+ goto done;
+ dksc->sc_busy = true;
+
/*
* Peeking at the buffer queue and committing the operation
* only after success isn't atomic.
@@ -339,6 +343,8 @@ dk_start(struct dk_softc *dksc, struct b
bp = bufq_get(dksc->sc_bufq);
}
+ dksc->sc_busy = false;
+done:
mutex_exit(&dksc->sc_iolock);
}
Index: src/sys/dev/dkvar.h
diff -u src/sys/dev/dkvar.h:1.22 src/sys/dev/dkvar.h:1.23
--- src/sys/dev/dkvar.h:1.22 Thu Aug 27 05:51:50 2015
+++ src/sys/dev/dkvar.h Fri Aug 28 05:49:31 2015
@@ -1,4 +1,4 @@
-/* $NetBSD: dkvar.h,v 1.22 2015/08/27 05:51:50 mlelstv Exp $ */
+/* $NetBSD: dkvar.h,v 1.23 2015/08/28 05:49:31 mlelstv Exp $ */
/*-
* Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -48,6 +48,7 @@ struct dk_softc {
struct bufq_state *sc_bufq; /* buffer queue */
int sc_dtype; /* disk type */
struct buf *sc_deferred; /* retry after start failed */
+ bool sc_busy; /* processing buffers */
};
/* sc_flags:
