On Mar 3, 2023, at 4:08 PM, Benjamin Coddington [off-list ref] 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 <redacted>
---
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;
-- 
2.31.1