5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: NeilBrown neilb@suse.de
[ Upstream commit 8c62d12740a1450d2e8456d5747f440e10db281a ]
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 --- fs/lockd/svc.c | 6 +----- fs/nfs/callback.c | 14 ++------------ fs/nfsd/nfsctl.c | 4 ++-- fs/nfsd/nfsd.h | 2 +- fs/nfsd/nfssvc.c | 30 ++++++++++++++++-------------- include/linux/sunrpc/svc.h | 26 +++++++++++++++++++++++--- net/sunrpc/svc.c | 19 +++++-------------- 7 files changed, 50 insertions(+), 51 deletions(-)
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c index 2f50d5b2a8a42..135bd86ed3adb 100644 --- a/fs/lockd/svc.c +++ b/fs/lockd/svc.c @@ -431,10 +431,6 @@ static struct svc_serv *lockd_create_svc(void) * Check whether we're already up and running. */ if (nlmsvc_rqst) - /* - * Note: increase service usage, because later in case of error - * svc_destroy() will be called. - */ return svc_get(nlmsvc_rqst->rq_server);
/* @@ -495,7 +491,7 @@ int lockd_up(struct net *net, const struct cred *cred) * so we exit through here on both success and failure. */ err_put: - svc_destroy(serv); + svc_put(serv); err_create: mutex_unlock(&nlmsvc_mutex); return error; diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c index 674198e0eb5e1..dddd66749a881 100644 --- a/fs/nfs/callback.c +++ b/fs/nfs/callback.c @@ -267,10 +267,6 @@ static struct svc_serv *nfs_callback_create_svc(int minorversion) * Check whether we're already up and running. */ if (cb_info->serv) - /* - * Note: increase service usage, because later in case of error - * svc_destroy() will be called. - */ return svc_get(cb_info->serv);
switch (minorversion) { @@ -333,16 +329,10 @@ int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt) goto err_start;
cb_info->users++; - /* - * svc_create creates the svc_serv with sv_nrthreads == 1, and then - * svc_prepare_thread increments that. So we need to call svc_destroy - * on both success and failure so that the refcount is 1 when the - * thread exits. - */ err_net: if (!cb_info->users) cb_info->serv = NULL; - svc_destroy(serv); + svc_put(serv); err_create: mutex_unlock(&nfs_callback_mutex); return ret; @@ -368,7 +358,7 @@ void nfs_callback_down(int minorversion, struct net *net) if (cb_info->users == 0) { svc_get(serv); serv->sv_ops->svo_setup(serv, NULL, 0); - svc_destroy(serv); + svc_put(serv); dprintk("nfs_callback_down: service destroyed\n"); cb_info->serv = NULL; } diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 162866cfe83a2..5c8d985acf5fb 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -743,7 +743,7 @@ static ssize_t __write_ports_addfd(char *buf, struct net *net, const struct cred
err = svc_addsock(nn->nfsd_serv, fd, buf, SIMPLE_TRANSACTION_LIMIT, cred); if (err < 0 && list_empty(&nn->nfsd_serv->sv_permsocks)) { - nfsd_destroy(net); + nfsd_put(net); return err; }
@@ -796,7 +796,7 @@ static ssize_t __write_ports_addxprt(char *buf, struct net *net, const struct cr if (!list_empty(&nn->nfsd_serv->sv_permsocks)) nn->nfsd_serv->sv_nrthreads--; else - nfsd_destroy(net); + nfsd_put(net); return err; }
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h index 498e5a4898260..3e5008b475ff0 100644 --- a/fs/nfsd/nfsd.h +++ b/fs/nfsd/nfsd.h @@ -97,7 +97,7 @@ int nfsd_pool_stats_open(struct inode *, struct file *); int nfsd_pool_stats_release(struct inode *, struct file *); void nfsd_shutdown_threads(struct net *net);
-void nfsd_destroy(struct net *net); +void nfsd_put(struct net *net);
bool i_am_nfsd(void);
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index 0f84151011088..4aee1cfe0d1bb 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -623,7 +623,7 @@ void nfsd_shutdown_threads(struct net *net) svc_get(serv); /* Kill outstanding nfsd threads */ serv->sv_ops->svo_setup(serv, NULL, 0); - nfsd_destroy(net); + nfsd_put(net); mutex_unlock(&nfsd_mutex); /* Wait for shutdown of nfsd_serv to complete */ wait_for_completion(&nn->nfsd_shutdown_complete); @@ -656,7 +656,10 @@ int nfsd_create_serv(struct net *net) nn->nfsd_serv->sv_maxconn = nn->max_connections; error = svc_bind(nn->nfsd_serv, net); if (error < 0) { - svc_destroy(nn->nfsd_serv); + /* NOT nfsd_put() as notifiers (see below) haven't + * been set up yet. + */ + svc_put(nn->nfsd_serv); nfsd_complete_shutdown(net); return error; } @@ -697,16 +700,16 @@ int nfsd_get_nrthreads(int n, int *nthreads, struct net *net) return 0; }
-void nfsd_destroy(struct net *net) +void nfsd_put(struct net *net) { struct nfsd_net *nn = net_generic(net, nfsd_net_id); - int destroy = (nn->nfsd_serv->sv_nrthreads == 1);
- if (destroy) + nn->nfsd_serv->sv_nrthreads -= 1; + if (nn->nfsd_serv->sv_nrthreads == 0) { svc_shutdown_net(nn->nfsd_serv, net); - svc_destroy(nn->nfsd_serv); - if (destroy) + svc_destroy(nn->nfsd_serv); nfsd_complete_shutdown(net); + } }
int nfsd_set_nrthreads(int n, int *nthreads, struct net *net) @@ -758,7 +761,7 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net) if (err) break; } - nfsd_destroy(net); + nfsd_put(net); return err; }
@@ -795,7 +798,7 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
error = nfsd_startup_net(net, cred); if (error) - goto out_destroy; + goto out_put; error = nn->nfsd_serv->sv_ops->svo_setup(nn->nfsd_serv, NULL, nrservs); if (error) @@ -808,8 +811,8 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred) out_shutdown: if (error < 0 && !nfsd_up_before) nfsd_shutdown_net(net); -out_destroy: - nfsd_destroy(net); /* Release server */ +out_put: + nfsd_put(net); out: mutex_unlock(&nfsd_mutex); return error; @@ -982,7 +985,7 @@ nfsd(void *vrqstp) /* Release the thread */ svc_exit_thread(rqstp);
- nfsd_destroy(net); + nfsd_put(net);
/* Release module */ mutex_unlock(&nfsd_mutex); @@ -1109,8 +1112,7 @@ int nfsd_pool_stats_release(struct inode *inode, struct file *file) struct net *net = inode->i_sb->s_fs_info;
mutex_lock(&nfsd_mutex); - /* this function really, really should have been called svc_put() */ - nfsd_destroy(net); + nfsd_put(net); mutex_unlock(&nfsd_mutex); return ret; } diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 80d44df8663db..b378e9ad141b4 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 @@ -517,7 +538,6 @@ 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 *, diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 36a3ad9336d6f..85f324418d175 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -528,17 +528,7 @@ EXPORT_SYMBOL_GPL(svc_shutdown_net); void svc_destroy(struct svc_serv *serv) { - dprintk("svc: svc_destroy(%s, %d)\n", - serv->sv_program->pg_name, - serv->sv_nrthreads); - - if (serv->sv_nrthreads) { - if (--(serv->sv_nrthreads) != 0) { - svc_sock_update_bufs(serv); - return; - } - } else - printk("svc_destroy: no threads for serv=%p!\n", serv); + dprintk("svc: svc_destroy(%s)\n", serv->sv_program->pg_name);
del_timer_sync(&serv->sv_temptimer);
@@ -896,9 +886,10 @@ svc_exit_thread(struct svc_rqst *rqstp)
svc_rqst_free(rqstp);
- /* Release the server */ - if (serv) - svc_destroy(serv); + if (!serv) + return; + svc_sock_update_bufs(serv); + svc_destroy(serv); } EXPORT_SYMBOL_GPL(svc_exit_thread);