On Fri, 2016-01-22 at 01:49 +0800, Xin Long wrote: > Previously, before rhashtable, /proc assoc listing was done by > read-locking the entire hash entry and dumping all assocs at once, so we > were sure that the assoc wasn't freed because it wouldn't be possible to > remove it from the hash meanwhile. > > Now we use rhashtable to list transports, and dump entries one by one. > That is, now we have to check if the assoc is still a good one, as the > transport we got may be being freed. > > Signed-off-by: Xin Long <lucien....@gmail.com> > --- > net/sctp/proc.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/net/sctp/proc.c b/net/sctp/proc.c > index 684c5b3..c74a810 100644 > --- a/net/sctp/proc.c > +++ b/net/sctp/proc.c > @@ -380,6 +380,8 @@ static int sctp_assocs_seq_show(struct seq_file *seq, > void *v) > } > > transport = (struct sctp_transport *)v;
What protects you from this structure already being freed ? > + if (!sctp_transport_hold(transport)) > + return 0; If this is rcu, then you do not need to increment the refcount, and decrement it later.
