Author: kib
Date: Sun Oct 6 06:05:11 2013
New Revision: 256076
URL: http://svnweb.freebsd.org/changeset/base/256076
Log:
MFC r255940:
Add LK_TRYUPGRADE operation for lockmgr(9).
Modified:
stable/9/sys/kern/kern_lock.c
stable/9/sys/sys/lockmgr.h
Directory Properties:
stable/9/sys/ (props changed)
stable/9/sys/sys/ (props changed)
Modified: stable/9/sys/kern/kern_lock.c
==============================================================================
--- stable/9/sys/kern/kern_lock.c Sun Oct 6 05:53:29 2013
(r256075)
+++ stable/9/sys/kern/kern_lock.c Sun Oct 6 06:05:11 2013
(r256076)
@@ -490,6 +490,7 @@ __lockmgr_args(struct lock *lk, u_int fl
op = LK_EXCLUSIVE;
break;
case LK_UPGRADE:
+ case LK_TRYUPGRADE:
case LK_DOWNGRADE:
_lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED,
file, line);
@@ -687,6 +688,7 @@ __lockmgr_args(struct lock *lk, u_int fl
}
break;
case LK_UPGRADE:
+ case LK_TRYUPGRADE:
_lockmgr_assert(lk, KA_SLOCKED, file, line);
v = lk->lk_lock;
x = v & LK_ALL_WAITERS;
@@ -707,6 +709,17 @@ __lockmgr_args(struct lock *lk, u_int fl
}
/*
+ * In LK_TRYUPGRADE mode, do not drop the lock,
+ * returning EBUSY instead.
+ */
+ if (op == LK_TRYUPGRADE) {
+ LOCK_LOG2(lk, "%s: %p failed the nowait upgrade",
+ __func__, lk);
+ error = EBUSY;
+ break;
+ }
+
+ /*
* We have been unable to succeed in upgrading, so just
* give up the shared lock.
*/
Modified: stable/9/sys/sys/lockmgr.h
==============================================================================
--- stable/9/sys/sys/lockmgr.h Sun Oct 6 05:53:29 2013 (r256075)
+++ stable/9/sys/sys/lockmgr.h Sun Oct 6 06:05:11 2013 (r256076)
@@ -168,6 +168,7 @@ _lockmgr_args_rw(struct lock *lk, u_int
#define LK_RELEASE 0x100000
#define LK_SHARED 0x200000
#define LK_UPGRADE 0x400000
+#define LK_TRYUPGRADE 0x800000
#define LK_TOTAL_MASK (LK_INIT_MASK | LK_EATTR_MASK | LK_TYPE_MASK)
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