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authorhannken <hannken@NetBSD.org>2023-03-14 12:55:43 +0000
committerhannken <hannken@NetBSD.org>2023-03-14 12:55:43 +0000
commit3c4e1b3b03829f927ed2ed94ca7420ca84598845 (patch)
tree6c1f2bc7361e0e8d6ecb5c160b4c29f3871957b0 /sys/dev
parentcb6a5a3575fd9678245ac90623c4fbe964c14704 (diff)
Do not limit the number of pending requests for the worker thread.
With wedge on vnd it prevents a deadlock when requests get queued with biodone() -> dkstart() -> vndstrategy(). Fixes PR kern/57263 "vnd locks up when using vn_rdwr"
Diffstat (limited to 'sys/dev')
-rw-r--r--sys/dev/vnd.c22
1 files changed, 14 insertions, 8 deletions
diff --git a/sys/dev/vnd.c b/sys/dev/vnd.c
index 8998f9b40b7..1e597b5e9b4 100644
--- a/sys/dev/vnd.c
+++ b/sys/dev/vnd.c
@@ -1,4 +1,4 @@
-/* $NetBSD: vnd.c,v 1.287 2022/09/04 21:56:38 mlelstv Exp $ */
+/* $NetBSD: vnd.c,v 1.288 2023/03/14 12:55:43 hannken Exp $ */
/*-
* Copyright (c) 1996, 1997, 1998, 2008, 2020 The NetBSD Foundation, Inc.
@@ -91,7 +91,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vnd.c,v 1.287 2022/09/04 21:56:38 mlelstv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vnd.c,v 1.288 2023/03/14 12:55:43 hannken Exp $");
#if defined(_KERNEL_OPT)
#include "opt_vnd.h"
@@ -553,11 +553,18 @@ vndstrategy(struct buf *bp)
printf("vndstrategy(%p): unit %d\n", bp, unit);
#endif
if ((vnd->sc_flags & VNF_USE_VN_RDWR)) {
- KASSERT(vnd->sc_pending >= 0 &&
- vnd->sc_pending <= VND_MAXPENDING(vnd));
- while (vnd->sc_pending == VND_MAXPENDING(vnd))
- tsleep(&vnd->sc_pending, PRIBIO, "vndpc", 0);
+ /*
+ * Limit the number of pending requests to not exhaust
+ * resources needed for I/O but always allow the worker
+ * thread to add requests, as a wedge on vnd queues
+ * requests with biodone() -> dkstart() -> vndstrategy().
+ */
+ if (curlwp != vnd->sc_kthread) {
+ while (vnd->sc_pending >= VND_MAXPENDING(vnd))
+ tsleep(&vnd->sc_pending, PRIBIO, "vndpc", 0);
+ }
vnd->sc_pending++;
+ KASSERT(vnd->sc_pending > 0);
}
bufq_put(vnd->sc_tab, bp);
wakeup(&vnd->sc_tab);
@@ -674,8 +681,7 @@ vndthread(void *arg)
continue;
};
if ((vnd->sc_flags & VNF_USE_VN_RDWR)) {
- KASSERT(vnd->sc_pending > 0 &&
- vnd->sc_pending <= VND_MAXPENDING(vnd));
+ KASSERT(vnd->sc_pending > 0);
if (vnd->sc_pending-- == VND_MAXPENDING(vnd))
wakeup(&vnd->sc_pending);
}