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-rw-r--r--fs/lockd/svc.c4
-rw-r--r--fs/nfs/callback.c2
-rw-r--r--fs/nfsd/netns.h7
-rw-r--r--fs/nfsd/nfsctl.c22
-rw-r--r--fs/nfsd/nfssvc.c42
-rw-r--r--include/linux/sunrpc/svc.h14
-rw-r--r--net/sunrpc/svc.c22
7 files changed, 59 insertions, 54 deletions
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 135bd86ed3ad..a9669b106dbd 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -486,10 +486,6 @@ int lockd_up(struct net *net, const struct cred *cred)
goto err_put;
}
nlmsvc_users++;
- /*
- * Note: svc_serv structures have an initial use count of 1,
- * so we exit through here on both success and failure.
- */
err_put:
svc_put(serv);
err_create:
diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index edbc7579b4aa..d9d78ffd1d65 100644
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -169,7 +169,7 @@ static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
if (nrservs < NFS4_MIN_NR_CALLBACK_THREADS)
nrservs = NFS4_MIN_NR_CALLBACK_THREADS;
- if (serv->sv_nrthreads-1 == nrservs)
+ if (serv->sv_nrthreads == nrservs)
return 0;
ret = serv->sv_ops->svo_setup(serv, NULL, nrservs);
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 935c1028c217..08bcd8f23b01 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -123,6 +123,13 @@ struct nfsd_net {
u32 clverifier_counter;
struct svc_serv *nfsd_serv;
+ /* When a listening socket is added to nfsd, keep_active is set
+ * and this justifies a reference on nfsd_serv. This stops
+ * nfsd_serv from being freed. When the number of threads is
+ * set, keep_active is cleared and the reference is dropped. So
+ * when the last thread exits, the service will be destroyed.
+ */
+ int keep_active;
wait_queue_head_t ntf_wq;
atomic_t ntf_refcnt;
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 17521fada83f..7b557eb8211a 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -742,13 +742,12 @@ static ssize_t __write_ports_addfd(char *buf, struct net *net, const struct cred
return err;
err = svc_addsock(nn->nfsd_serv, fd, buf, SIMPLE_TRANSACTION_LIMIT, cred);
- if (err < 0 && list_empty(&nn->nfsd_serv->sv_permsocks)) {
- nfsd_put(net);
- return err;
- }
- /* Decrease the count, but don't shut down the service */
- nn->nfsd_serv->sv_nrthreads--;
+ if (err >= 0 &&
+ !nn->nfsd_serv->sv_nrthreads && !xchg(&nn->keep_active, 1))
+ svc_get(nn->nfsd_serv);
+
+ nfsd_put(net);
return err;
}
@@ -783,8 +782,10 @@ static ssize_t __write_ports_addxprt(char *buf, struct net *net, const struct cr
if (err < 0 && err != -EAFNOSUPPORT)
goto out_close;
- /* Decrease the count, but don't shut down the service */
- nn->nfsd_serv->sv_nrthreads--;
+ if (!nn->nfsd_serv->sv_nrthreads && !xchg(&nn->keep_active, 1))
+ svc_get(nn->nfsd_serv);
+
+ nfsd_put(net);
return 0;
out_close:
xprt = svc_find_xprt(nn->nfsd_serv, transport, net, PF_INET, port);
@@ -793,10 +794,7 @@ out_close:
svc_xprt_put(xprt);
}
out_err:
- if (!list_empty(&nn->nfsd_serv->sv_permsocks))
- nn->nfsd_serv->sv_nrthreads--;
- else
- nfsd_put(net);
+ nfsd_put(net);
return err;
}
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index a0a7564e6c73..5f605e7e8091 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -60,13 +60,13 @@ static __be32 nfsd_init_request(struct svc_rqst *,
* extent ->sv_temp_socks and ->sv_permsocks. It also protects nfsdstats.th_cnt
*
* If (out side the lock) nn->nfsd_serv is non-NULL, then it must point to a
- * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0. That number
- * of nfsd threads must exist and each must listed in ->sp_all_threads in each
- * entry of ->sv_pools[].
+ * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0 (unless
+ * nn->keep_active is set). That number of nfsd threads must
+ * exist and each must be listed in ->sp_all_threads in some entry of
+ * ->sv_pools[].
*
- * Transitions of the thread count between zero and non-zero are of particular
- * interest since the svc_serv needs to be created and initialized at that
- * point, or freed.
+ * Each active thread holds a counted reference on nn->nfsd_serv, as does
+ * the nn->keep_active flag and various transient calls to svc_get().
*
* Finally, the nfsd_mutex also protects some of the global variables that are
* accessed when nfsd starts and that are settable via the write_* routines in
@@ -700,14 +700,22 @@ int nfsd_get_nrthreads(int n, int *nthreads, struct net *net)
return 0;
}
+/* This is the callback for kref_put() below.
+ * There is no code here as the first thing to be done is
+ * call svc_shutdown_net(), but we cannot get the 'net' from
+ * the kref. So do all the work when kref_put returns true.
+ */
+static void nfsd_noop(struct kref *ref)
+{
+}
+
void nfsd_put(struct net *net)
{
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
- nn->nfsd_serv->sv_nrthreads -= 1;
- if (nn->nfsd_serv->sv_nrthreads == 0) {
+ if (kref_put(&nn->nfsd_serv->sv_refcnt, nfsd_noop)) {
svc_shutdown_net(nn->nfsd_serv, net);
- svc_destroy(nn->nfsd_serv);
+ svc_destroy(&nn->nfsd_serv->sv_refcnt);
nfsd_complete_shutdown(net);
}
}
@@ -803,15 +811,14 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
NULL, nrservs);
if (error)
goto out_shutdown;
- /* We are holding a reference to nn->nfsd_serv which
- * we don't want to count in the return value,
- * so subtract 1
- */
- error = nn->nfsd_serv->sv_nrthreads - 1;
+ error = nn->nfsd_serv->sv_nrthreads;
out_shutdown:
if (error < 0 && !nfsd_up_before)
nfsd_shutdown_net(net);
out_put:
+ /* Threads now hold service active */
+ if (xchg(&nn->keep_active, 0))
+ nfsd_put(net);
nfsd_put(net);
out:
mutex_unlock(&nfsd_mutex);
@@ -980,11 +987,15 @@ nfsd(void *vrqstp)
nfsdstats.th_cnt --;
out:
- rqstp->rq_server = NULL;
+ /* 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);
+ /* Now if needed we call svc_destroy in appropriate context */
nfsd_put(net);
/* Release module */
@@ -1099,7 +1110,6 @@ int nfsd_pool_stats_open(struct inode *inode, struct file *file)
mutex_unlock(&nfsd_mutex);
return -ENODEV;
}
- /* bump up the psudo refcount while traversing */
svc_get(nn->nfsd_serv);
ret = svc_pool_stats_open(nn->nfsd_serv, file);
mutex_unlock(&nfsd_mutex);
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 73d56d33a36d..3903b4ae8ac5 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -85,6 +85,7 @@ struct svc_serv {
struct svc_program * sv_program; /* RPC program */
struct svc_stat * sv_stats; /* RPC statistics */
spinlock_t sv_lock;
+ struct kref sv_refcnt;
unsigned int sv_nrthreads; /* # of server threads */
unsigned int sv_maxconn; /* max connections allowed or
* '0' causing max to be based
@@ -119,19 +120,14 @@ struct svc_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.
*/
static inline struct svc_serv *svc_get(struct svc_serv *serv)
{
- serv->sv_nrthreads++;
+ kref_get(&serv->sv_refcnt);
return serv;
}
-void svc_destroy(struct svc_serv *serv);
+void svc_destroy(struct kref *);
/**
* svc_put - decrement reference count on a SUNRPC serv
@@ -142,9 +138,7 @@ void svc_destroy(struct svc_serv *serv);
*/
static inline void svc_put(struct svc_serv *serv)
{
- serv->sv_nrthreads -= 1;
- if (serv->sv_nrthreads == 0)
- svc_destroy(serv);
+ kref_put(&serv->sv_refcnt, svc_destroy);
}
/*
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 55a1bf0d129f..acddc6e12e9e 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -435,7 +435,7 @@ __svc_create(struct svc_program *prog, unsigned int bufsize, int npools,
return NULL;
serv->sv_name = prog->pg_name;
serv->sv_program = prog;
- serv->sv_nrthreads = 1;
+ kref_init(&serv->sv_refcnt);
serv->sv_stats = prog->pg_stats;
if (bufsize > RPCSVC_MAXPAYLOAD)
bufsize = RPCSVC_MAXPAYLOAD;
@@ -526,10 +526,11 @@ EXPORT_SYMBOL_GPL(svc_shutdown_net);
* protect the sv_nrthreads, sv_permsocks and sv_tempsocks.
*/
void
-svc_destroy(struct svc_serv *serv)
+svc_destroy(struct kref *ref)
{
- dprintk("svc: svc_destroy(%s)\n", serv->sv_program->pg_name);
+ struct svc_serv *serv = container_of(ref, struct svc_serv, sv_refcnt);
+ dprintk("svc: svc_destroy(%s)\n", serv->sv_program->pg_name);
del_timer_sync(&serv->sv_temptimer);
/*
@@ -637,6 +638,7 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node)
if (!rqstp)
return ERR_PTR(-ENOMEM);
+ svc_get(serv);
serv->sv_nrthreads++;
spin_lock_bh(&pool->sp_lock);
pool->sp_nrthreads++;
@@ -776,8 +778,7 @@ int
svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{
if (pool == NULL) {
- /* The -1 assumes caller has done a svc_get() */
- nrservs -= (serv->sv_nrthreads-1);
+ nrservs -= serv->sv_nrthreads;
} else {
spin_lock_bh(&pool->sp_lock);
nrservs -= pool->sp_nrthreads;
@@ -814,8 +815,7 @@ int
svc_set_num_threads_sync(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{
if (pool == NULL) {
- /* The -1 assumes caller has done a svc_get() */
- nrservs -= (serv->sv_nrthreads-1);
+ nrservs -= serv->sv_nrthreads;
} else {
spin_lock_bh(&pool->sp_lock);
nrservs -= pool->sp_nrthreads;
@@ -880,12 +880,12 @@ svc_exit_thread(struct svc_rqst *rqstp)
list_del_rcu(&rqstp->rq_all);
spin_unlock_bh(&pool->sp_lock);
+ serv->sv_nrthreads -= 1;
+ svc_sock_update_bufs(serv);
+
svc_rqst_free(rqstp);
- if (!serv)
- return;
- svc_sock_update_bufs(serv);
- svc_destroy(serv);
+ svc_put(serv);
}
EXPORT_SYMBOL_GPL(svc_exit_thread);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.