linux-kernel - [PATCH 4.9 034/130] sunrpc: dont call sleeping functions from the notifier block callbacks

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Date:   Tue, 24 Jan 2017 08:54:34 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Scott Mayhew <smayhew@...hat.com>,
        "J. Bruce Fields" <bfields@...hat.com>
Subject: [PATCH 4.9 034/130] sunrpc: dont call sleeping functions from the notifier block callbacks

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Scott Mayhew <smayhew@...hat.com>

commit 546125d1614264d26080817d0c8cddb9b25081fa upstream.

The inet6addr_chain is an atomic notifier chain, so we can't call
anything that might sleep (like lock_sock)... instead of closing the
socket from svc_age_temp_xprts_now (which is called by the notifier
function), just have the rpc service threads do it instead.

Fixes: c3d4879e01be "sunrpc: Add a function to close..."
Signed-off-by: Scott Mayhew <smayhew@...hat.com>
Signed-off-by: J. Bruce Fields <bfields@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 include/linux/sunrpc/svc_xprt.h |    1 +
 net/sunrpc/svc_xprt.c           |   10 +++++++---
 2 files changed, 8 insertions(+), 3 deletions(-)

--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -66,6 +66,7 @@ struct svc_xprt {
 #define XPT_LISTENER	10		/* listening endpoint */
 #define XPT_CACHE_AUTH	11		/* cache auth info */
 #define XPT_LOCAL	12		/* connection from loopback interface */
+#define XPT_KILL_TEMP   13		/* call xpo_kill_temp_xprt before closing */
 
 	struct svc_serv		*xpt_server;	/* service for transport */
 	atomic_t    	    	xpt_reserved;	/* space on outq that is rsvd */
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -799,6 +799,8 @@ static int svc_handle_xprt(struct svc_rq
 
 	if (test_bit(XPT_CLOSE, &xprt->xpt_flags)) {
 		dprintk("svc_recv: found XPT_CLOSE\n");
+		if (test_and_clear_bit(XPT_KILL_TEMP, &xprt->xpt_flags))
+			xprt->xpt_ops->xpo_kill_temp_xprt(xprt);
 		svc_delete_xprt(xprt);
 		/* Leave XPT_BUSY set on the dead xprt: */
 		goto out;
@@ -1020,9 +1022,11 @@ void svc_age_temp_xprts_now(struct svc_s
 		le = to_be_closed.next;
 		list_del_init(le);
 		xprt = list_entry(le, struct svc_xprt, xpt_list);
-		dprintk("svc_age_temp_xprts_now: closing %p\n", xprt);
-		xprt->xpt_ops->xpo_kill_temp_xprt(xprt);
-		svc_close_xprt(xprt);
+		set_bit(XPT_CLOSE, &xprt->xpt_flags);
+		set_bit(XPT_KILL_TEMP, &xprt->xpt_flags);
+		dprintk("svc_age_temp_xprts_now: queuing xprt %p for closing\n",
+				xprt);
+		svc_xprt_enqueue(xprt);
 	}
 }
 EXPORT_SYMBOL_GPL(svc_age_temp_xprts_now);