Re: [PATCH 4/5] sctp: protocol.c call rcu_barrier() on unload.

Paul E. McKenney
2009-06-08T16:22:27Z

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@linux.vnet.ibm.com>

> Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
> ---
>
> 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);
> }
>