From: NeilBrown <neilb@xxxxxxx>
[ 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: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/nfsd/nfssvc.c | 23 -----------------------
include/linux/sunrpc/svc.h | 13 -------------
2 files changed, 36 deletions(-)
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -983,31 +983,8 @@ nfsd(void *vrqstp)
atomic_dec(&nfsd_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;
}
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -123,19 +123,6 @@ static inline void svc_put(struct svc_se
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
Patches currently in stable-queue which might be from cel@xxxxxxxxxx are
queue-6.1/nfsd-simplify-code-around-svc_exit_thread-call-in-nfsd.patch
queue-6.1/nfsd-separate-nfsd_last_thread-from-nfsd_put.patch
queue-6.1/nfsd-simplify-error-paths-in-nfsd_svc.patch
queue-6.1/nfsd-fix-a-regression-in-nfsd_setattr.patch
queue-6.1/nfsd-drop-the-nfsd_put-helper.patch
queue-6.1/nfsd-call-nfsd_last_thread-before-final-nfsd_put.patch
queue-6.1/nfsd-don-t-call-locks_release_private-twice-concurrently.patch
