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 > > 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. > > 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. > > Approved by: r...@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 == 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 = prev;
> } else {
> /* Everything got collapsed out?? */
> - SCTP_INP_READ_UNLOCK(inp);
> + if (inp_read_lock_held == 0)
> + SCTP_INP_READ_UNLOCK(inp);
> return;
> }
> if (end) {
> control->end_added = 1;
> }
> TAILQ_INSERT_TAIL(&inp->read_queue, control, next);
> - SCTP_INP_READ_UNLOCK(inp);
> + if (inp_read_lock_held == 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?
--
Pawel Jakub Dawidek http://www.wheel.pl
p...@freebsd.org http://www.FreeBSD.org
FreeBSD committer Am I Evil? Yes, I Am!
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