Re: [PATCH v3 3/4] SUNRPC: new helper function for stopping backchannel server

[Anna Schumaker <anna.schumaker@oracle.com>]

Hi Olga,

On 11/3/25 5:13 PM, Olga Kornievskaia wrote:
> Create a new backchannel function to stop the backchannel server
> and clear the bc_serv in transport protected under the bc_pa_lock.
> 
> Signed-off-by: Olga Kornievskaia <okorniev@redhat.com>
> ---
>  include/linux/sunrpc/bc_xprt.h |  5 +++++
>  net/sunrpc/backchannel_rqst.c  | 16 ++++++++++++++++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/include/linux/sunrpc/bc_xprt.h b/include/linux/sunrpc/bc_xprt.h
> index 178f34ad8db6..9cac8f442fd4 100644
> --- a/include/linux/sunrpc/bc_xprt.h
> +++ b/include/linux/sunrpc/bc_xprt.h
> @@ -32,6 +32,7 @@ int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs);
>  void xprt_destroy_bc(struct rpc_xprt *xprt, unsigned int max_reqs);
>  void xprt_free_bc_rqst(struct rpc_rqst *req);
>  unsigned int xprt_bc_max_slots(struct rpc_xprt *xprt);
> +void xprt_svc_destroy_nullify_bc(struct rpc_xprt *xprt, struct svc_serv **serv);
>  
>  /*
>   * Determine if a shared backchannel is in use
> @@ -69,5 +70,9 @@ static inline void set_bc_enabled(struct svc_serv *serv)
>  static inline void xprt_free_bc_request(struct rpc_rqst *req)
>  {
>  }

Can you add an extra line of whitespace between xprt_free_bc_request() and
xprt_svc_destroy_nullify_bc()?

> +static void xprt_svc_destroy_nullify_bc(struct rpc_xprt *xprt, struct svc_serv **serv)

I think the build warning is being triggered because this function isn't being
marked as "inline". If you fix that up, it should go away.

Thanks,
Anna

> +{
> +	svc_destroy(serv);
> +}
>  #endif /* CONFIG_SUNRPC_BACKCHANNEL */
>  #endif /* _LINUX_SUNRPC_BC_XPRT_H */
> diff --git a/net/sunrpc/backchannel_rqst.c b/net/sunrpc/backchannel_rqst.c
> index efddea0f4b8b..68b1fcdea8f0 100644
> --- a/net/sunrpc/backchannel_rqst.c
> +++ b/net/sunrpc/backchannel_rqst.c
> @@ -24,6 +24,22 @@ unsigned int xprt_bc_max_slots(struct rpc_xprt *xprt)
>  	return BC_MAX_SLOTS;
>  }
>  
> +/*
> + * Helper function to nullify backchannel server pointer in transport.
> + * We need to synchronize setting the pointer to NULL (done so after
> + * the backchannel server is shutdown) with the usage of that pointer
> + * by the backchannel request processing routines
> + * xprt_complete_bc_request() and rpcrdma_bc_receive_call().
> + */
> +void xprt_svc_destroy_nullify_bc(struct rpc_xprt *xprt, struct svc_serv **serv)
> +{
> +	spin_lock(&xprt->bc_pa_lock);
> +	svc_destroy(serv);
> +	xprt->bc_serv = NULL;
> +	spin_unlock(&xprt->bc_pa_lock);
> +}
> +EXPORT_SYMBOL_GPL(xprt_svc_destroy_nullify_bc);
> +
>  /*
>   * Helper routines that track the number of preallocation elements
>   * on the transport.