linux-kernel - [PATCH 2/4] cifs, freezer: add wait_event

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Date:	Wed, 28 Sep 2011 07:52:39 -0400
From:	Jeff Layton <jlayton@...hat.com>
To:	trond.myklebust@...app.com, smfrench@...il.com, pavel@....cz,
	rjw@...k.pl
Cc:	linux-pm@...ts.linux-foundation.org, linux-cifs@...r.kernel.org,
	linux-nfs@...r.kernel.org, john@...va.COM,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] cifs, freezer: add wait_event_freezekillable and have cifs use it

CIFS currently uses wait_event_killable to put tasks to sleep while
they await replies from the server. That function though does not
allow the freezer to run. In many cases, the network interface may
be going down anyway, in which case the reply will never come. The
client then ends up blocking the computer from suspending.

Fix this by adding a new wait_event_freezable variant --
wait_event_freezekillable. The idea is to combine the behavior of
wait_event_killable and wait_event_freezable -- put the task to
sleep and only allow it to be awoken by fatal signals, but also
allow the freezer to do its job.

Signed-off-by: Jeff Layton <jlayton@...hat.com>
---
 fs/cifs/transport.c     |    3 ++-
 include/linux/freezer.h |   19 +++++++++++++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 10ca6b2..791bc4f 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -26,6 +26,7 @@
 #include <linux/wait.h>
 #include <linux/net.h>
 #include <linux/delay.h>
+#include <linux/freezer.h>
 #include <asm/uaccess.h>
 #include <asm/processor.h>
 #include <linux/mempool.h>
@@ -324,7 +325,7 @@ wait_for_response(struct TCP_Server_Info *server, struct mid_q_entry *midQ)
 {
 	int error;
 
-	error = wait_event_killable(server->response_q,
+	error = wait_event_freezekillable(server->response_q,
 				    midQ->midState != MID_REQUEST_SUBMITTED);
 	if (error < 0)
 		return -ERESTARTSYS;
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 1effc8b..3672f73 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -134,10 +134,25 @@ static inline void set_freezable_with_signal(void)
 }
 
 /*
- * Freezer-friendly wrappers around wait_event_interruptible() and
- * wait_event_interruptible_timeout(), originally defined in <linux/wait.h>
+ * Freezer-friendly wrappers around wait_event_interruptible(),
+ * wait_event_killable() and wait_event_interruptible_timeout(), originally
+ * defined in <linux/wait.h>
  */
 
+#define wait_event_freezekillable(wq, condition)			\
+({									\
+	int __retval;							\
+	do {								\
+		__retval = wait_event_killable(wq, 			\
+				(condition) || freezing(current));	\
+		if (__retval && !freezing(current))			\
+			break;						\
+		else if (!(condition))					\
+			__retval = -ERESTARTSYS;			\
+	} while (try_to_freeze());					\
+	__retval;							\
+})
+
 #define wait_event_freezable(wq, condition)				\
 ({									\
 	int __retval;							\
-- 
1.7.6.2

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