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Date:      Mon, 7 Jul 2014 09:23:57 +0300
From:      Konstantin Belousov <kostikbel@gmail.com>
To:        Mateusz Guzik <mjguzik@gmail.com>
Cc:        svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Mateusz Guzik <mjg@FreeBSD.org>
Subject:   Re: svn commit: r268087 - head/sys/kern
Message-ID:  <20140707062357.GF93733@kib.kiev.ua>
In-Reply-To: <20140706213900.GB17706@dft-labs.eu>
References:  <201407010921.s619LXHL063077@svn.freebsd.org> <20140701114245.GO93733@kib.kiev.ua> <20140701115612.GA26696@dft-labs.eu> <20140701123058.GP93733@kib.kiev.ua> <20140701125410.GB26696@dft-labs.eu> <20140701180903.GT93733@kib.kiev.ua> <20140706211850.GA17706@dft-labs.eu> <20140706213900.GB17706@dft-labs.eu>

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On Sun, Jul 06, 2014 at 11:39:00PM +0200, Mateusz Guzik wrote:
> On Sun, Jul 06, 2014 at 11:18:51PM +0200, Mateusz Guzik wrote:
> > On Tue, Jul 01, 2014 at 09:09:03PM +0300, Konstantin Belousov wrote:
> > > On Tue, Jul 01, 2014 at 02:54:10PM +0200, Mateusz Guzik wrote:
> > > > It is passed down to MAC (mac_vnode_execve_will_transition and
> > > > mac_vnode_execve_transition) and then vfs_mark_atime.
> > > And we can lock it only there.
> > >=20
> >=20
> > I don't see how this code could be reorganized to reduce vnode lock
> > coverage and not add unlock + lock pair to the common case (no hwpmc and
> > no credential change).
> >=20
> > vfs_mark_atime is only called when execve cannot return an error
> > anymore, with vnode locked and proc unlocked. Moving it before hwpmc
> > checks would require additional pair of proc unlock/lock.
> >=20
> > That said, I would prefer to just commit previously proposed fixup.
> >=20
Ok.

>=20
> hm, I only now notice that fexecve case does:
> vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY)
>=20
> I guess this can be safely changed to LK_SHARED.

No, it cannot.  The VV_TEXT flag must be handled under the exclusive lock.

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