svn commit: r256177 - stable/9/share/man/man9

[Konstantin Belousov]

Author: kib
Date: Wed Oct  9 05:27:21 2013
New Revision: 256177
URL: http://svnweb.freebsd.org/changeset/base/256177

Log:
  MFC r256089:
  Document LK_TRYUPGRADE.

Modified:
  stable/9/share/man/man9/lock.9
Directory Properties:
  stable/9/share/man/man9/   (props changed)

Modified: stable/9/share/man/man9/lock.9
==============================================================================
--- stable/9/share/man/man9/lock.9	Wed Oct  9 03:56:07 2013	(r256176)
+++ stable/9/share/man/man9/lock.9	Wed Oct  9 05:27:21 2013	(r256177)
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd June 16, 2009
+.Dd October 6, 2013
 .Dt LOCK 9
 .Os
 .Sh NAME
@@ -164,11 +164,17 @@ If an exclusive lock has been recursed, 
 .Xr panic 9 .
 .It Dv LK_UPGRADE
 Upgrade a shared lock to an exclusive lock.
-If this call fails, the shared lock is lost.
+If this call fails, the shared lock is lost, even if the
+.Dv LK_NOWAIT
+flag is specified.
 During the upgrade, the shared lock could
 be temporarily dropped.
 Attempts to upgrade an exclusive lock will cause a
 .Xr panic 9 .
+.It Dv LK_TRYUPGRADE
+Try to upgrade a shared lock to an exclusive lock.
+The failure to upgrade does not result in the dropping
+of the shared lock ownership.
 .It Dv LK_RELEASE
 Release the lock.
 Releasing a lock that is not held can cause a
@@ -334,7 +340,9 @@ fail if:
 was requested and another thread had already requested a lock upgrade.
 .It Bq Er EBUSY
 .Dv LK_NOWAIT
-was set, and a sleep would have been required.
+was set, and a sleep would have been required, or
+.Dv LK_TRYUPGRADE
+operation was not able to upgrade the lock.
 .It Bq Er ENOLCK
 .Dv LK_SLEEPFAIL
 was set and