Re: [PATCH] netfilter: Remove duplicated rcu_read_lock.

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Wed, May 24, 2017 at 03:25:41PM +0300, Julian Anastasov wrote:
> 
> 	Hello,
> 
> 	The IPVS part from patch looks good but can be extended
> to also remove rcu_read_lock and rcu_read_unlock from:
> 
> 1. all app_conn_bind methods because ip_vs_bind_app() is called
> always under RCU lock from ip_vs_try_bind_dest() and ip_vs_conn_new().
> I.e. from sctp_app_conn_bind, tcp_app_conn_bind and udp_app_conn_bind.
> 
> 2. ip_vs_xmit.c, all locks
> 
> 	IMHO, using comments instead of locks is not needed, it is
> enough that the commit message explains why RCU locks are removed
> 
> 	More details:
> 
> In IPVS we have the following contexts:
> - packet RX/TX: does not need locks because packets come from hooks
> - sync msg RX: backup server uses RCU locks while registering new conns
> - ip_vs_ctl.c: configuration get/set, RCU locks needed
> - xt_ipvs.c: It is a NF match
> 
> As result, rcu_read_lock and rcu_read_unlock can be removed from:
> - ip_vs_core.c: all
> - ip_vs_ctl.c:
> 	- from ip_vs_has_real_service
> 	- all other places need the RCU locking
> - ip_vs_ftp.c: all
> - ip_vs_proto_sctp.c: all
> - ip_vs_proto_tcp.c: all
> - ip_vs_proto_udp.c: all
> - ip_vs_xmit.c: all (contains only packet processing)
> 
> Locks should remain in:
> - ip_vs_conn.c
> - ip_vs_pe.c
> - ip_vs_sync.c

Julian, thanks a lot for this careful review!

I have marked this patch as "Changed Requested".

Thanks.