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Date: Sun, 14 Dec 2014 00:31:11 +0300
From: Chagin Dmitry <dchagin@freebsd.org>
To: Benjamin Kaduk <bjkfbsd@gmail.com>
Subject: Re: svn commit: r275751 - in head: share/man/man9 sys/kern sys/sys
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On Sat, Dec 13, 2014 at 04:03:47PM -0500, Benjamin Kaduk wrote:
> On Sat, Dec 13, 2014 at 4:00 PM, Dmitry Chagin <dchagin@freebsd.org> wrot=
e:
> >
> > Author: dchagin
> > Date: Sat Dec 13 21:00:10 2014
> > New Revision: 275751
> > URL: https://svnweb.freebsd.org/changeset/base/275751
> >
> > Log:
> >   Add _NEW flag to mtx(9), sx(9), rmlock(9) and rwlock(9).
> >   A _NEW flag passed to _init_flags() to avoid check for double-init.
> >
> >
> Can you please say a bit more about why this is desired and what it will =
be
> used for?
>=20
If the kernel has been compiled with INVARIANTS _init() will assert that the
lock has not been initialized multiple times. _NEW flag is needed to skip t=
his.
as _init() does expect you to zero lock first.
it should be used carefully, when you are sure its safe,
to avoid bzero'ing lock struct. ugh

--=20
Have fun!
chd

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