This is a note to let you know that I've just added the patch titled
nfsd: Simplify code around svc_exit_thread() call in nfsd()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfsd-simplify-code-around-svc_exit_thread-call-in-nf.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 49a3ee549083513fdc5c72e4bf8a3d9d16612b5f
Author: NeilBrown <neilb@xxxxxxx>
Date: Mon Jul 31 16:48:31 2023 +1000
nfsd: Simplify code around svc_exit_thread() call in nfsd()
[ Upstream commit 18e4cf915543257eae2925671934937163f5639b ]
Previously a thread could exit asynchronously (due to a signal) so some
care was needed to hold nfsd_mutex over the last svc_put() call. Now a
thread can only exit when svc_set_num_threads() is called, and this is
always called under nfsd_mutex. So no care is needed.
Not only is the mutex held when a thread exits now, but the svc refcount
is elevated, so the svc_put() in svc_exit_thread() will never be a final
put, so the mutex isn't even needed at this point in the code.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 8063fab2c0279..8907dba22c3f2 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -979,31 +979,8 @@ nfsd(void *vrqstp)
atomic_dec(&nfsdstats.th_cnt);
out:
- /* Take an extra ref so that the svc_put in svc_exit_thread()
- * doesn't call svc_destroy()
- */
- svc_get(nn->nfsd_serv);
-
/* Release the thread */
svc_exit_thread(rqstp);
-
- /* We need to drop a ref, but may not drop the last reference
- * without holding nfsd_mutex, and we cannot wait for nfsd_mutex as that
- * could deadlock with nfsd_shutdown_threads() waiting for us.
- * So three options are:
- * - drop a non-final reference,
- * - get the mutex without waiting
- * - sleep briefly andd try the above again
- */
- while (!svc_put_not_last(nn->nfsd_serv)) {
- if (mutex_trylock(&nfsd_mutex)) {
- nfsd_put(net);
- mutex_unlock(&nfsd_mutex);
- break;
- }
- msleep(20);
- }
-
return 0;
}
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 5cf6543d3c8e5..1cf7a7799cc04 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -123,19 +123,6 @@ static inline void svc_put(struct svc_serv *serv)
kref_put(&serv->sv_refcnt, svc_destroy);
}
-/**
- * svc_put_not_last - decrement non-final reference count on SUNRPC serv
- * @serv: the svc_serv to have count decremented
- *
- * Returns: %true is refcount was decremented.
- *
- * If the refcount is 1, it is not decremented and instead failure is reported.
- */
-static inline bool svc_put_not_last(struct svc_serv *serv)
-{
- return refcount_dec_not_one(&serv->sv_refcnt.refcount);
-}
-
/*
* Maximum payload size supported by a kernel RPC server.
* This is use to determine the max number of pages nfsd is
