On Fri, 2023-03-03 at 16:08 -0500, Benjamin Coddington wrote:
> Fix a race where kthread_stop() may prevent the threadfn from ever getting
> called. If that happens the svc_rqst will not be cleaned up.
>
> Fixes: ed6473ddc704 ("NFSv4: Fix callback server shutdown")
> Signed-off-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
> ---
> net/sunrpc/svc.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
> index 1fd3f5e57285..fea7ce8fba14 100644
> --- a/net/sunrpc/svc.c
> +++ b/net/sunrpc/svc.c
> @@ -798,6 +798,7 @@ svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
> static int
> svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
> {
> + struct svc_rqst *rqstp;
> struct task_struct *task;
> unsigned int state = serv->sv_nrthreads-1;
>
> @@ -806,7 +807,10 @@ svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
> task = choose_victim(serv, pool, &state);
> if (task == NULL)
> break;
> - kthread_stop(task);
> + rqstp = kthread_data(task);
> + /* Did we lose a race to svo_function threadfn? */
> + if (kthread_stop(task) == -EINTR)
> + svc_exit_thread(rqstp);
> nrservs++;
> } while (nrservs < 0);
> return 0;
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
