linux-kernel - [PATCH] remove the BKL: remove "BKL auto-drop" assumption from nfs3_rpc

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Date:	Fri, 10 Apr 2009 18:34:41 +0200
From:	Alessio Igor Bogani <abogani@...ware.it>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Jonathan Corbet <corbet@....net>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	LKML <linux-kernel@...r.kernel.org>,
	Alessio Igor Bogani <abogani@...ware.it>
Subject: [PATCH] remove the BKL: remove "BKL auto-drop" assumption from nfs3_rpc_wrapper()

Fix nfs3_rpc_wrapper()'s "schedule() drops the BKL automatically" assumption,
when schedule_timeout_killable() does not do that it can lock up.

Signed-off-by: Alessio Igor Bogani <abogani@...ware.it>
---
 fs/nfs/nfs3proc.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
index d0cc5ce..d91047c 100644
--- a/fs/nfs/nfs3proc.c
+++ b/fs/nfs/nfs3proc.c
@@ -17,6 +17,7 @@
 #include <linux/nfs_page.h>
 #include <linux/lockd/bind.h>
 #include <linux/nfs_mount.h>
+#include <linux/smp_lock.h>
 
 #include "iostat.h"
 #include "internal.h"
@@ -28,11 +29,17 @@ static int
 nfs3_rpc_wrapper(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
 {
 	int res;
+	int bkl = kernel_locked();
+
 	do {
 		res = rpc_call_sync(clnt, msg, flags);
 		if (res != -EJUKEBOX)
 			break;
+		if (bkl)
+			unlock_kernel();
 		schedule_timeout_killable(NFS_JUKEBOX_RETRY_TIME);
+		if (bkl)
+			lock_kernel();
 		res = -ERESTARTSYS;
 	} while (!fatal_signal_pending(current));
 	return res;
-- 
1.6.0.4

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