Re: [PATCH 2/2] nfs: do not start the callback thread until we set rqstp->rq_task

[Christoph Hellwig <hch@infradead.org>]

On Tue, Sep 02, 2014 at 01:58:58PM -0400, Trond Myklebust wrote:
> This fixes an Oopsable race when starting up the callback server.
> 
> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
> ---
>  fs/nfs/callback.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
> index e3dd1cd175d9..b8fb3a4ef649 100644
> --- a/fs/nfs/callback.c
> +++ b/fs/nfs/callback.c
> @@ -235,7 +235,7 @@ static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
>  
>  	cb_info->serv = serv;
>  	cb_info->rqst = rqstp;
> -	cb_info->task = kthread_run(callback_svc, cb_info->rqst,
> +	cb_info->task = kthread_create(callback_svc, cb_info->rqst,
>  				    "nfsv4.%u-svc", minorversion);
>  	if (IS_ERR(cb_info->task)) {
>  		ret = PTR_ERR(cb_info->task);
> @@ -245,6 +245,7 @@ static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
>  		return ret;
>  	}
>  	rqstp->rq_task = cb_info->task;
> +	wake_up_process(cb_info->task);

Wouldn't it be cleaner to do something like:

-	cb_info->task = kthread_run(callback_svc, cb_info->rqst,
+	cb_info->task = rqstp->rq_run =
+		kthread_create(callback_svc, cb_info->rqst,

or am I missing something subtile that the changelog didn't mention?