On Thu, 24 Aug 2006, Julian Elischer wrote:
Konstantin Belousov wrote:
kib 2006-08-24 10:16:01 UTC
FreeBSD src repository
Modified files: (Branch: RELENG_6)
share/man/man9 lock.9 Log:
MFC rev.1.14:
Note that LK_UPGRADE may drop the shared lock before taking the
exclusive one.
excuse my ignorance but I though that the whole aim of an upgrade was to
make sure that you did NOT drop it before getting the exclusive lock..( or
it fails and you back out and retry)
This is a feature and a bug. :-)
In order to avoid deadlock on upgrade, one of two things must happen:
- The upgrade must be able to fail -- i.e., sx(9)'s sx_try_upgrade().
- A race must be introduced in which the shared lock is released before an
exclusive lock is acquired -- i.e., lockmgr(9)'s LK_UPGRADE.
Consumers of lockmgr(9) -- specifically, VFS, are aware of this. Documenting
it is good, however. :-)
Robert N M Watson
Computer Laboratory
University of Cambridge
_______________________________________________
[email protected] mailing list
http://lists.freebsd.org/mailman/listinfo/cvs-all
To unsubscribe, send any mail to "[EMAIL PROTECTED]"
