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Message-ID: <20130212205216.GE10267@fieldses.org>
Date: Tue, 12 Feb 2013 15:52:17 -0500
From: "J. Bruce Fields" <bfields@...ldses.org>
To: Mark Lord <kernel@...savvy.com>
Cc: Stanislav Kinsbursky <skinsbursky@...allels.com>,
linux-nfs@...r.kernel.org,
Linux Kernel <linux-kernel@...r.kernel.org>,
Paweł Sikora <pawel.sikora@...k.net>,
Tom Horsley <horsley1953@...il.com>
Subject: Re: BUG at net/sunrpc/svc_xprt.c:921 (another one)
On Sun, Jan 20, 2013 at 05:51:12PM -0500, Mark Lord wrote:
> Got it again, this time on a different system
> running mostly the same software.
Mark, Paweł, Tom, could any of you confirm whether this helps?
--b.
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index dbf12ac..2d34b6b 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -515,15 +515,6 @@ EXPORT_SYMBOL_GPL(svc_create_pooled);
void svc_shutdown_net(struct svc_serv *serv, struct net *net)
{
- /*
- * The set of xprts (contained in the sv_tempsocks and
- * sv_permsocks lists) is now constant, since it is modified
- * only by accepting new sockets (done by service threads in
- * svc_recv) or aging old ones (done by sv_temptimer), or
- * configuration changes (excluded by whatever locking the
- * caller is using--nfsd_mutex in the case of nfsd). So it's
- * safe to traverse those lists and shut everything down:
- */
svc_close_net(serv, net);
if (serv->sv_shutdown)
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index b8e47fa..ca71056 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -856,7 +856,6 @@ static void svc_age_temp_xprts(unsigned long closure)
struct svc_serv *serv = (struct svc_serv *)closure;
struct svc_xprt *xprt;
struct list_head *le, *next;
- LIST_HEAD(to_be_aged);
dprintk("svc_age_temp_xprts\n");
@@ -877,25 +876,15 @@ static void svc_age_temp_xprts(unsigned long closure)
if (atomic_read(&xprt->xpt_ref.refcount) > 1 ||
test_bit(XPT_BUSY, &xprt->xpt_flags))
continue;
- svc_xprt_get(xprt);
- list_move(le, &to_be_aged);
+ list_del_init(le);
set_bit(XPT_CLOSE, &xprt->xpt_flags);
set_bit(XPT_DETACHED, &xprt->xpt_flags);
- }
- spin_unlock_bh(&serv->sv_lock);
-
- while (!list_empty(&to_be_aged)) {
- le = to_be_aged.next;
- /* fiddling the xpt_list node is safe 'cos we're XPT_DETACHED */
- list_del_init(le);
- xprt = list_entry(le, struct svc_xprt, xpt_list);
-
dprintk("queuing xprt %p for closing\n", xprt);
/* a thread will dequeue and close it soon */
svc_xprt_enqueue(xprt);
- svc_xprt_put(xprt);
}
+ spin_unlock_bh(&serv->sv_lock);
mod_timer(&serv->sv_temptimer, jiffies + svc_conn_age_period * HZ);
}
@@ -959,21 +948,24 @@ void svc_close_xprt(struct svc_xprt *xprt)
}
EXPORT_SYMBOL_GPL(svc_close_xprt);
-static void svc_close_list(struct svc_serv *serv, struct list_head *xprt_list, struct net *net)
+static int svc_close_list(struct svc_serv *serv, struct list_head *xprt_list, struct net *net)
{
struct svc_xprt *xprt;
+ int ret = 0;
spin_lock(&serv->sv_lock);
list_for_each_entry(xprt, xprt_list, xpt_list) {
if (xprt->xpt_net != net)
continue;
+ ret++;
set_bit(XPT_CLOSE, &xprt->xpt_flags);
- set_bit(XPT_BUSY, &xprt->xpt_flags);
+ svc_xprt_enqueue(xprt);
}
spin_unlock(&serv->sv_lock);
+ return ret;
}
-static void svc_clear_pools(struct svc_serv *serv, struct net *net)
+static struct svc_xprt *svc_dequeue_net(struct svc_serv *serv, struct net *net)
{
struct svc_pool *pool;
struct svc_xprt *xprt;
@@ -988,42 +980,46 @@ static void svc_clear_pools(struct svc_serv *serv, struct net *net)
if (xprt->xpt_net != net)
continue;
list_del_init(&xprt->xpt_ready);
+ spin_unlock_bh(&pool->sp_lock);
+ return xprt;
}
spin_unlock_bh(&pool->sp_lock);
}
+ return NULL;
}
-static void svc_clear_list(struct svc_serv *serv, struct list_head *xprt_list, struct net *net)
+static void svc_clean_up_xprts(struct svc_serv *serv, struct net *net)
{
struct svc_xprt *xprt;
- struct svc_xprt *tmp;
- LIST_HEAD(victims);
-
- spin_lock(&serv->sv_lock);
- list_for_each_entry_safe(xprt, tmp, xprt_list, xpt_list) {
- if (xprt->xpt_net != net)
- continue;
- list_move(&xprt->xpt_list, &victims);
- }
- spin_unlock(&serv->sv_lock);
- list_for_each_entry_safe(xprt, tmp, &victims, xpt_list)
+ while ((xprt = svc_dequeue_net(serv, net))) {
+ set_bit(XPT_CLOSE, &xprt->xpt_flags);
svc_delete_xprt(xprt);
+ }
}
+/*
+ * Server threads may still be running (especially in the case where the
+ * service is still running in other network namespaces).
+ *
+ * So we shut down sockets the same way we would on a running server, by
+ * setting XPT_CLOSE, enqueuing, and letting a thread pick it up to do
+ * the close. In the case there are no such other threads,
+ * threads running, svc_clean_up_xprts() does a simple version of a
+ * server's main event loop, and in the case where there are other
+ * threads, we may need to wait a little while and then check again to
+ * see if they're done.
+ */
void svc_close_net(struct svc_serv *serv, struct net *net)
{
- svc_close_list(serv, &serv->sv_tempsocks, net);
- svc_close_list(serv, &serv->sv_permsocks, net);
+ int delay = 0;
- svc_clear_pools(serv, net);
- /*
- * At this point the sp_sockets lists will stay empty, since
- * svc_xprt_enqueue will not add new entries without taking the
- * sp_lock and checking XPT_BUSY.
- */
- svc_clear_list(serv, &serv->sv_tempsocks, net);
- svc_clear_list(serv, &serv->sv_permsocks, net);
+ while (svc_close_list(serv, &serv->sv_permsocks, net) +
+ svc_close_list(serv, &serv->sv_tempsocks, net)) {
+
+ svc_clean_up_xprts(serv, net);
+ msleep(delay++);
+ }
}
/*
--
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