Re: [PATCH 01/14] lockd: remove SIGKILL handling.

[Jeff Layton <jlayton@kernel.org>]

On Tue, 2023-07-18 at 16:38 +1000, NeilBrown wrote:
> lockd allows SIGKILL and responds by dropping all locks and restarting
> the grace period.  This functionality has been present since 2.1.32 when
> lockd was added to Linux.
> 
> This functionality is undocumented and most liked added as a useful
> debug aid.  When there is a need to drop locks, the best approach is
> using /proc/fs/nfsd/unlock_*.
> 
> This patch removes the handling of SIGKILL as part of preparation for
> removing all signal handling from sunrpc service threads.
> 
> Signed-off-by: NeilBrown <neilb@suse.de>
> ---
>  fs/lockd/svc.c |   24 ------------------------
>  1 file changed, 24 deletions(-)
> 
> diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
> index 22d3ff3818f5..614faa5f69cd 100644
> --- a/fs/lockd/svc.c
> +++ b/fs/lockd/svc.c
> @@ -45,7 +45,6 @@
>  
>  #define NLMDBG_FACILITY		NLMDBG_SVC
>  #define LOCKD_BUFSIZE		(1024 + NLMSVC_XDRSIZE)
> -#define ALLOWED_SIGS		(sigmask(SIGKILL))
>  
>  static struct svc_program	nlmsvc_program;
>  
> @@ -111,19 +110,6 @@ static void set_grace_period(struct net *net)
>  	schedule_delayed_work(&ln->grace_period_end, grace_period);
>  }
>  
> -static void restart_grace(void)
> -{
> -	if (nlmsvc_ops) {
> -		struct net *net = &init_net;
> -		struct lockd_net *ln = net_generic(net, lockd_net_id);
> -
> -		cancel_delayed_work_sync(&ln->grace_period_end);
> -		locks_end_grace(&ln->lockd_manager);
> -		nlmsvc_invalidate_all();
> -		set_grace_period(net);
> -	}
> -}
> -
>  /*
>   * This is the lockd kernel thread
>   */
> @@ -138,9 +124,6 @@ lockd(void *vrqstp)
>  	/* try_to_freeze() is called from svc_recv() */
>  	set_freezable();
>  
> -	/* Allow SIGKILL to tell lockd to drop all of its locks */
> -	allow_signal(SIGKILL);
> -
>  	dprintk("NFS locking service started (ver " LOCKD_VERSION ").\n");
>  
>  	/*
> @@ -154,12 +137,6 @@ lockd(void *vrqstp)
>  		/* update sv_maxconn if it has changed */
>  		rqstp->rq_server->sv_maxconn = nlm_max_connections;
>  
> -		if (signalled()) {
> -			flush_signals(current);
> -			restart_grace();
> -			continue;
> -		}
> -
>  		timeout = nlmsvc_retry_blocked();
>  
>  		/*
> @@ -174,7 +151,6 @@ lockd(void *vrqstp)
>  
>  		svc_process(rqstp);
>  	}
> -	flush_signals(current);
>  	if (nlmsvc_ops)
>  		nlmsvc_invalidate_all();
>  	nlm_shutdown_hosts();
> 
> 

Nice to finally do this!

Reviewed-by: Jeff Layton <jlayton@kernel.org>