Paul E. McKenney wrote: > On Tue, Jun 09, 2009 at 11:44:23AM -0400, Vlad Yasevich wrote: >> Paul E. McKenney wrote: >>> On Mon, Jun 08, 2009 at 03:11:43PM +0200, Jesper Dangaard Brouer wrote: >>>> On module unload call rcu_barrier(), this is needed as synchronize_rcu() >>>> is not strong enough. The kmem_cache_destroy() does invoke >>>> synchronize_rcu() but it does not provide same protection. >>> Good, looks like sctp_v4_del_protocol() invokes call_rcu(), which the >>> rcu_barrier() would then wait for. And it looks like sctp_v6_del_protocol() >>> does the same for IPv6. >>> >>> Reviewed_by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> >>> >>>> Signed-off-by: Jesper Dangaard Brouer <hawk@xxxxxxx> >>>> --- >>>> >>>> net/sctp/protocol.c | 2 ++ >>>> 1 files changed, 2 insertions(+), 0 deletions(-) >>>> >>>> diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c >>>> index cb2c50d..79cbd47 100644 >>>> --- a/net/sctp/protocol.c >>>> +++ b/net/sctp/protocol.c >>>> @@ -1370,6 +1370,8 @@ SCTP_STATIC __exit void sctp_exit(void) >>>> sctp_proc_exit(); >>>> cleanup_sctp_mibs(); >>>> >>>> + rcu_barrier(); /* Wait for completion of call_rcu()'s */ >>>> + >>>> kmem_cache_destroy(sctp_chunk_cachep); >>>> kmem_cache_destroy(sctp_bucket_cachep); >>>> } >> Shouldn't the rcu_barrier call be before sctp_free_local_addr_list()? > > Hmmm... What sequence of events would lead to a failure if > rcu_barrier() is after sctp_free_local_addr_list()? > > Thanx, Paul > I thought that the notifier could could potentially execute at the same time as the unregister(), but I see that's protected. So, I guess it doesn't really matter then where the barrier is. Acked-by: Vlad Yasevich <vladislav.yasevich@xxxxxx> -vlad -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
