5.15-stable review patch. If anyone has any objections, please let me know.
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From: NeilBrown neilb@suse.de
[ 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@suse.de Signed-off-by: Chuck Lever chuck.lever@oracle.com --- fs/nfsd/nfssvc.c | 23 ----------------------- include/linux/sunrpc/svc.h | 13 ------------- 2 files changed, 36 deletions(-)
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 53405c282209f..6e48c1c88f1bb 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