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From:   "NeilBrown" <neilb@suse.de>
To:     "Chuck Lever" <cel@kernel.org>
Cc:     brauner@kernel.org, "Chuck Lever" <chuck.lever@oracle.com>,
        linux-nfs@vger.kernel.org
Subject: Re: [PATCH v1] SUNRPC: Remove BUG_ON call sites
In-reply-to: <169504668787.134583.4338728458451666583.stgit@manet.1015granger.net>
References: <169504668787.134583.4338728458451666583.stgit@manet.1015granger.net>
Date:   Tue, 19 Sep 2023 10:02:07 +1000
Message-id: <169508172758.19404.11033097632795181738@noble.neil.brown.name>
Precedence: bulk

On Tue, 19 Sep 2023, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
> 
> There is no need to take down the whole system for these assertions.
> 
> I'd rather not attempt a heroic save here, as some bug has occurred
> that has left the transport data structures in an unknown state.
> Just warn and then leak the left-over resources.
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  net/sunrpc/svc.c |   11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> Let's start here. Comments?
> 
> 
> diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
> index 587811a002c9..11a1d5e7f5c7 100644
> --- a/net/sunrpc/svc.c
> +++ b/net/sunrpc/svc.c
> @@ -575,11 +575,14 @@ svc_destroy(struct kref *ref)
>  	timer_shutdown_sync(&serv->sv_temptimer);
>  
>  	/*
> -	 * The last user is gone and thus all sockets have to be destroyed to
> -	 * the point. Check this.
> +	 * Remaining transports at this point are not expected.
>  	 */
> -	BUG_ON(!list_empty(&serv->sv_permsocks));
> -	BUG_ON(!list_empty(&serv->sv_tempsocks));
> +	if (unlikely(!list_empty(&serv->sv_permsocks)))
> +		pr_warn("SVC: permsocks remain for %s\n",
> +			serv->sv_program->pg_name);

I would go with WARN_ON_ONCE() but I agree with the principle.
Maybe
  WARN_ONCE(!list_empty(&serv->sv_permsocks), 
            "SVC: permsocks remain for %s\n",
	    serv->sv_program->pg_name);
This gives the stack trace which might be helpful.
But 

 Reviewed-by: NeilBrown <neilb@suse.de>

if you prefer it the way it is.

NeilBrown

> +	if (unlikely(!list_empty(&serv->sv_tempsocks)))
> +		pr_warn("SVC: tempsocks remain for %s\n",
> +			serv->sv_program->pg_name);
>  
>  	cache_clean_deferred(serv);
>  
> 
> 
>