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Subject: Re: [PATCH RFC2 2/2] sunrpc: Ensure signalled RPC tasks exit
From:   Chuck Lever <chuck.lever@oracle.com>
In-Reply-To: <20200423194317.7849.3375.stgit@manet.1015granger.net>
Date:   Thu, 23 Apr 2020 15:43:53 -0400
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        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
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 <20200423194317.7849.3375.stgit@manet.1015granger.net>
To:     Chuck Lever <chuck.lever@oracle.com>
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Sigh.

I forgot to set the command line flag to compose a cover letter.
Let me get to that.


> On Apr 23, 2020, at 3:43 PM, Chuck Lever <chuck.lever@oracle.com> wrote:
> 
> If an RPC task is signaled while it is running and the transport is
> not connected, it will never sleep and never be terminated. This can
> happen when a RPC transport is shut down: the remaining tasks are
> signalled, but the transport is disconnected.
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
> include/linux/sunrpc/sched.h |    3 ++-
> net/sunrpc/sched.c           |   14 ++++++--------
> 2 files changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
> index df696efdd675..9f5e48f154c5 100644
> --- a/include/linux/sunrpc/sched.h
> +++ b/include/linux/sunrpc/sched.h
> @@ -170,7 +170,8 @@ struct rpc_task_setup {
> 
> #define RPC_IS_ACTIVATED(t)	test_bit(RPC_TASK_ACTIVE, &(t)->tk_runstate)
> 
> -#define RPC_SIGNALLED(t)	test_bit(RPC_TASK_SIGNALLED, &(t)->tk_runstate)
> +#define RPC_SIGNALLED(t)	\
> +	unlikely(test_bit(RPC_TASK_SIGNALLED, &(t)->tk_runstate) != 0)
> 
> /*
>  * Task priorities.
> diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
> index 7eba20a88438..99b7b834a110 100644
> --- a/net/sunrpc/sched.c
> +++ b/net/sunrpc/sched.c
> @@ -912,6 +912,12 @@ static void __rpc_execute(struct rpc_task *task)
> 		trace_rpc_task_run_action(task, do_action);
> 		do_action(task);
> 
> +		if (RPC_SIGNALLED(task)) {
> +			task->tk_rpc_status = -ERESTARTSYS;
> +			rpc_exit(task, -ERESTARTSYS);
> +			break;
> +		}
> +
> 		/*
> 		 * Lockless check for whether task is sleeping or not.
> 		 */
> @@ -919,14 +925,6 @@ static void __rpc_execute(struct rpc_task *task)
> 			continue;
> 
> 		/*
> -		 * Signalled tasks should exit rather than sleep.
> -		 */
> -		if (RPC_SIGNALLED(task)) {
> -			task->tk_rpc_status = -ERESTARTSYS;
> -			rpc_exit(task, -ERESTARTSYS);
> -		}
> -
> -		/*
> 		 * The queue->lock protects against races with
> 		 * rpc_make_runnable().
> 		 *
> 

--
Chuck Lever