Date: Wed, 29 Jul 2009 07:10:16 +0200 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Randall Stewart <rrs@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r195918 - head/sys/netinet Message-ID: <20090729051016.GB3550@garage.freebsd.pl> In-Reply-To: <200907281409.n6SE971u034585@svn.freebsd.org> References: <200907281409.n6SE971u034585@svn.freebsd.org>
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--yEPQxsgoJgBvi8ip Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jul 28, 2009 at 02:09:07PM +0000, Randall Stewart wrote: > Author: rrs > Date: Tue Jul 28 14:09:06 2009 > New Revision: 195918 > URL: http://svn.freebsd.org/changeset/base/195918 >=20 > Log: > Turns out that when a receiver forwards through its TNS's the > processing code holds the read lock (when processing a > FWD-TSN for pr-sctp). If it finds stranded data that > can be given to the application, it calls sctp_add_to_readq(). > The readq function also grabs this lock. So if INVAR is on > we get a double recurse on a non-recursive lock and panic. > =20 > This fix will change it so that readq() function gets a > flag to tell if the lock is held, if so then it does not > get the lock. > =20 > Approved by: re@freebsd.org (Kostik Belousov) > MFC after: 1 week [...] > sctp_add_to_readq(stcb->sctp_ep, stcb, control, > - &stcb->sctp_socket->so_rcv, 1, so_locked); > + &stcb->sctp_socket->so_rcv, 1, SCTP_READ_LOCK_NOT_HELD, so_locked); [...] > @@ -4301,6 +4306,7 @@ sctp_add_to_readq(struct sctp_inpcb *inp > struct sctp_queued_to_read *control, > struct sockbuf *sb, > int end, > + int inp_read_lock_held, > int so_locked > #if !defined(__APPLE__) && !defined(SCTP_SO_LOCK_TESTING) > SCTP_UNUSED > @@ -4321,7 +4327,8 @@ sctp_add_to_readq(struct sctp_inpcb *inp > #endif > return; > } > - SCTP_INP_READ_LOCK(inp); > + if (inp_read_lock_held =3D=3D 0) It would be a bit cleaner to compare with SCTP_READ_LOCK_NOT_HELD here, instead of 0. > + SCTP_INP_READ_LOCK(inp); > if (!(control->spec_flags & M_NOTIFICATION)) { > atomic_add_int(&inp->total_recvs, 1); > if (!control->do_not_ref_stcb) { > @@ -4362,14 +4369,16 @@ sctp_add_to_readq(struct sctp_inpcb *inp > control->tail_mbuf =3D prev; > } else { > /* Everything got collapsed out?? */ > - SCTP_INP_READ_UNLOCK(inp); > + if (inp_read_lock_held =3D=3D 0) > + SCTP_INP_READ_UNLOCK(inp); > return; > } > if (end) { > control->end_added =3D 1; > } > TAILQ_INSERT_TAIL(&inp->read_queue, control, next); > - SCTP_INP_READ_UNLOCK(inp); > + if (inp_read_lock_held =3D=3D 0) > + SCTP_INP_READ_UNLOCK(inp); > if (inp && inp->sctp_socket) { > if (sctp_is_feature_on(inp, SCTP_PCB_FLAGS_ZERO_COPY_ACTIVE)) { > SCTP_ZERO_COPY_EVENT(inp, inp->sctp_socket); Instead of using additional argument to the sctp_add_to_readq() function, wouldn't it be sufficient to just check with mtx_owned(9) if the lock is already held? --=20 Pawel Jakub Dawidek http://www.wheel.pl pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! --yEPQxsgoJgBvi8ip Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQFKb9m4ForvXbEpPzQRAh/FAJ0Uc/bklivoexP+BYV0cx6dFI69fwCgs6in SiImPQCzfLDftrdDiobxcDg= =W5Wi -----END PGP SIGNATURE----- --yEPQxsgoJgBvi8ip--
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