Date: Tue, 28 May 2019 20:12:56 -0700 From: Gleb Smirnoff <glebius@freebsd.org> To: "Andrey V. Elsukov" <bu7cher@yandex.ru> Cc: "Andrey V. Elsukov" <ae@freebsd.org>, kib@freebsd.org, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r348303 - head/sys/net Message-ID: <20190529031256.GE21836@FreeBSD.org> In-Reply-To: <a7694fb5-2353-fcc1-5bfe-04064fc5825c@yandex.ru> References: <201905271241.x4RCffTm047128@repo.freebsd.org> <20190529001046.GC21836@FreeBSD.org> <a7694fb5-2353-fcc1-5bfe-04064fc5825c@yandex.ru>
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On Wed, May 29, 2019 at 03:23:23AM +0300, Andrey V. Elsukov wrote:
A> > --- a/FreeBSD/sys/net/bpf.c
A> > +++ b/FreeBSD/sys/net/bpf.c
A> > @@ -857,7 +857,6 @@ bpf_detachd_locked(struct bpf_d *d, bool detached_ifp)
A> > /* Save bd_writer value */
A> > error = d->bd_writer;
A> > ifp = bp->bif_ifp;
A> > - d->bd_bif = NULL;
A> > if (detached_ifp) {
A> > /*
A> > * Notify descriptor as it's detached, so that any
A> >
A> > Since every bpf_d holds a reference on bpf_if until delayed free happens,
A> > the the bpf_if is going to be valid.
A> >
A> > This allows not to use epoch_wait and run fully async. The patch above is
A> > a minimal patch: with NULL assignment removed, several more pieces of code
A> > can be removed in bpf.c
A> >
A> > Of course your patch also is going to work, but what do you think:
A> > are there any landmines with fully async approach?
A>
A> Hi,
A>
A> bpf_mtap() is not the only consumer of bd_bif, some of them expect it
A> becomes NULL when descriptor is detached.
May be then make a flag attached/detached?
--
Gleb Smirnoff
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