Re: [PATCH v2 2/2] NFSv4.x/callback: make sure callback threads are interruptible

[Kinglong Mee <kinglongmee@gmail.com>]

Ping ...

With the [1/2]??

thanks,
Kinglong Mee

On 1/19/2017 16:37, Kinglong Mee wrote:
> 
> 
> Commit bb6aeba736ba "NFSv4.x: Switch to using svc_set_num_threads()
>  to manage the callback threads" change nfs start/stop threads
> through svc_set_num_threads().
> 
> It destroy old threads by SIGINT signal, but our nfs4_callback_svc()
> isn't interruptible. So that, the callback threads will never be killed.
> 
> # mount -t nfs -overs=4.2 nfstestnic:/ /mnt/
> # ps -ajx |grep NFS
>     2  5927     0     0 ?           -1 S        0   0:00 [NFSv4 callback]
> # umount /mnt
> # ps -ajx |grep NFS
>     2  5927     0     0 ?           -1 S        0   0:00 [NFSv4 callback]
> # mount -t nfs -overs=4.2 nfstestnic:/ /mnt/
> # umount /mnt
> # ps -ajx |grep NFS
>     2  5927     0     0 ?           -1 S        0   0:00 [NFSv4 callback]
>     2  5963     0     0 ?           -1 S        0   0:00 [NFSv4 callback]
> 
> After one mount, there will be one callback thread left that cannot killed,
> the same time, nfs.ko will never be unplugged.
> 
> v2, drop the wrong setting of rqstp->rq_server = NULL
> 
> Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
> ---
>  fs/nfs/callback.c | 39 +++++++++++++++++++++++++++++++++++----
>  1 file changed, 35 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
> index 0a21150..2a0fffd 100644
> --- a/fs/nfs/callback.c
> +++ b/fs/nfs/callback.c
> @@ -73,6 +73,15 @@ nfs4_callback_svc(void *vrqstp)
>  	int err;
>  	struct svc_rqst *rqstp = vrqstp;
>  
> +	/*
> +	 * thread is spawned with all signals set to SIG_IGN, re-enable
> +	 * the ones that will bring down the thread
> +	 */
> +	allow_signal(SIGKILL);
> +	allow_signal(SIGHUP);
> +	allow_signal(SIGINT);
> +	allow_signal(SIGQUIT);
> +
>  	set_freezable();
>  
>  	while (!kthread_should_stop()) {
> @@ -80,11 +89,18 @@ nfs4_callback_svc(void *vrqstp)
>  		 * Listen for a request on the socket
>  		 */
>  		err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
> -		if (err == -EAGAIN || err == -EINTR)
> +		if (err == -EAGAIN)
>  			continue;
> +		else if (err == -EINTR)
> +			break;
>  		svc_process(rqstp);
>  	}
> -	return 0;
> +
> +	flush_signals(current);
> +
> +	/* Release the thread */
> +	svc_exit_thread(rqstp);
> +	module_put_and_exit(0);
>  }
>  
>  #if defined(CONFIG_NFS_V4_1)
> @@ -100,6 +116,15 @@ nfs41_callback_svc(void *vrqstp)
>  	int error;
>  	DEFINE_WAIT(wq);
>  
> +	/*
> +	 * thread is spawned with all signals set to SIG_IGN, re-enable
> +	 * the ones that will bring down the thread
> +	 */
> +	allow_signal(SIGKILL);
> +	allow_signal(SIGHUP);
> +	allow_signal(SIGINT);
> +	allow_signal(SIGQUIT);
> +
>  	set_freezable();
>  
>  	while (!kthread_should_stop()) {
> @@ -121,11 +146,17 @@ nfs41_callback_svc(void *vrqstp)
>  		} else {
>  			spin_unlock_bh(&serv->sv_cb_lock);
>  			schedule();
> +			if (signalled())
> +				break;
>  			finish_wait(&serv->sv_cb_waitq, &wq);
>  		}
> -		flush_signals(current);
>  	}
> -	return 0;
> +
> +	flush_signals(current);
> +
> +	/* Release the thread */
> +	svc_exit_thread(rqstp);
> +	module_put_and_exit(0);
>  }
>  
>  static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
>