[src/trunk]: src/sys/dev/dkwedge dk(4): Don't hold lock around uiomove in dkw...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d1cf1ed5d1a6
branches:  trunk
changeset: 375932:d1cf1ed5d1a6
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Mon May 22 14:59:16 2023 +0000

description:
dk(4): Don't hold lock around uiomove in dkwedge_list.

Instead, hold a device reference.  dkwedge_detach will not run until
the device reference is released.

diffstat:

 sys/dev/dkwedge/dk.c |  14 ++++++++++++--
 1 files changed, 12 insertions(+), 2 deletions(-)

diffs (38 lines):

diff -r fc3f55edd701 -r d1cf1ed5d1a6 sys/dev/dkwedge/dk.c
--- a/sys/dev/dkwedge/dk.c      Mon May 22 14:59:07 2023 +0000
+++ b/sys/dev/dkwedge/dk.c      Mon May 22 14:59:16 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: dk.c,v 1.163 2023/05/22 14:59:07 riastradh Exp $       */
+/*     $NetBSD: dk.c,v 1.164 2023/05/22 14:59:16 riastradh Exp $       */
 
 /*-
  * Copyright (c) 2004, 2005, 2006, 2007 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: dk.c,v 1.163 2023/05/22 14:59:07 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: dk.c,v 1.164 2023/05/22 14:59:16 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_dkwedge.h"
@@ -862,9 +862,19 @@ dkwedge_list(struct disk *pdk, struct dk
                dkw.dkw_size = dkwedge_size(sc);
                strlcpy(dkw.dkw_ptype, sc->sc_ptype, sizeof(dkw.dkw_ptype));
 
+               /*
+                * Acquire a device reference so this wedge doesn't go
+                * away before our next iteration in LIST_FOREACH, and
+                * then release the lock for uiomove.
+                */
+               device_acquire(sc->sc_dev);
+               mutex_exit(&pdk->dk_openlock);
                error = uiomove(&dkw, sizeof(dkw), &uio);
+               mutex_enter(&pdk->dk_openlock);
+               device_release(sc->sc_dev);
                if (error)
                        break;
+
                dkwl->dkwl_ncopied++;
        }
        dkwl->dkwl_nwedges = pdk->dk_nwedges;