SUNRPC: Fix a server shutdown leak

[ Upstream commit 9ca6705d9d609441d34f8b853e1e4a6369b3b171 ]

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@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 24577d1..9ee32e0 100644 (file)
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -787,6 +787,7 @@ 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;
 
@@ -795,7 +796,10 @@ 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;