SUNRPC/NFSD: clean up get/put functions.

svc_destroy() is poorly named - it doesn't necessarily destroy the svc,
it might just reduce the ref count.
nfsd_destroy() is poorly named for the same reason.

This patch:
 - removes the refcount functionality from svc_destroy(), moving it to
   a new svc_put().  Almost all previous callers of svc_destroy() now
   call svc_put().
 - renames nfsd_destroy() to nfsd_put() and improves the code, using
   the new svc_destroy() rather than svc_put()
 - removes a few comments that explain the important for balanced
   get/put calls.  This should be obvious.

The only non-trivial part of this is that svc_destroy() would call
svc_sock_update() on a non-final decrement.  It can no longer do that,
and svc_put() isn't really a good place of it.  This call is now made
from svc_exit_thread() which seems like a good place.  This makes the
call *before* sv_nrthreads is decremented rather than after.  This
is not particularly important as the call just sets a flag which
causes sv_nrthreads set be checked later.  A subsequent patch will
improve the ordering.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

1 files changed, 23 insertions, 3 deletions

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 5d9568953fcd..73d56d33a36d 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -114,8 +114,13 @@ struct svc_serv {
 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
 };
 
-/*
- * We use sv_nrthreads as a reference count.  svc_destroy() drops
+/**
+ * svc_get() - increment reference count on a SUNRPC serv
+ * @serv:  the svc_serv to have count incremented
+ *
+ * Returns: the svc_serv that was passed in.
+ *
+ * We use sv_nrthreads as a reference count.  svc_put() drops
  * this refcount, so we need to bump it up around operations that
  * change the number of threads.  Horrible, but there it is.
  * Should be called with the "service mutex" held.
@@ -126,6 +131,22 @@ static inline struct svc_serv *svc_get(struct svc_serv *serv)
 	return serv;
 }
 
+void svc_destroy(struct svc_serv *serv);
+
+/**
+ * svc_put - decrement reference count on a SUNRPC serv
+ * @serv:  the svc_serv to have count decremented
+ *
+ * When the reference count reaches zero, svc_destroy()
+ * is called to clean up and free the serv.
+ */
+static inline void svc_put(struct svc_serv *serv)
+{
+	serv->sv_nrthreads -= 1;
+	if (serv->sv_nrthreads == 0)
+		svc_destroy(serv);
+}
+
 /*
  * Maximum payload size supported by a kernel RPC server.
  * This is use to determine the max number of pages nfsd is
@@ -515,7 +536,6 @@ struct svc_serv *  svc_create_pooled(struct svc_program *, unsigned int,
 int		   svc_set_num_threads(struct svc_serv *, struct svc_pool *, int);
 int		   svc_set_num_threads_sync(struct svc_serv *, struct svc_pool *, int);
 int		   svc_pool_stats_open(struct svc_serv *serv, struct file *file);
-void		   svc_destroy(struct svc_serv *);
 void		   svc_shutdown_net(struct svc_serv *, struct net *);
 int		   svc_process(struct svc_rqst *);
 int		   bc_svc_process(struct svc_serv *, struct rpc_rqst *,