linux-kernel - [Patch 02/08] Staging: heci - fix wrong order of device_lock and file

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Message-ID: <EADF0A36011179459010BDF5142A457501C9BF2AE0@pdsmsx502.ccr.corp.intel.com>
Date:	Sun, 31 May 2009 14:43:39 +0800
From:	"Xu, Dongxiao" <dongxiao.xu@...el.com>
To:	"greg@...ah.com" <greg@...ah.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Nashif, Anas" <anas.nashif@...el.com>,
	"Obara, Marcin" <marcin.obara@...el.com>
Subject: [Patch 02/08] Staging: heci - fix wrong order of device_lock and
 file_lock

>From 5c4db44364f204d168d2bbb70310728a54aabcd7 Mon Sep 17 00:00:00 2001
From: Dongxiao Xu <dongxiao.xu@...el.com>
Date: Sun, 31 May 2009 22:44:09 +0800
Subject: [PATCH] heci: fix wrong order of device_lock and file_lock

When the two locks are nested, the code should always first acquire file_lock,
and then acquire device_lock in order not to generate dead-lock race.

Signed-off-by: Dongxiao Xu <dongxiao.xu@...el.com>
---
 drivers/staging/heci/io_heci.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/heci/io_heci.c b/drivers/staging/heci/io_heci.c
index ff6d294..26882a2 100644
--- a/drivers/staging/heci/io_heci.c
+++ b/drivers/staging/heci/io_heci.c
@@ -277,14 +277,16 @@ int heci_ioctl_connect_client(struct iamt_heci_device *dev, int if_num,
 		}
 		goto end;
 	}
+	spin_unlock_bh(&dev->device_lock);
+
 	spin_lock(&file_ext->file_lock);
+	spin_lock_bh(&dev->device_lock);
 	if (file_ext->state != HECI_FILE_CONNECTING) {
 		rets = -ENODEV;
-		spin_unlock(&file_ext->file_lock);
 		spin_unlock_bh(&dev->device_lock);
+		spin_unlock(&file_ext->file_lock);
 		goto end;
 	}
-	spin_unlock(&file_ext->file_lock);
 	/* prepare the output buffer */
 	client = (struct heci_client *) res_msg.data;
 	client->max_msg_length = dev->me_clients[i].props.max_msg_length;
@@ -312,6 +314,7 @@ int heci_ioctl_connect_client(struct iamt_heci_device *dev, int if_num,
 			      &dev->ctrl_wr_list.heci_cb.cb_list);
 	}
 	spin_unlock_bh(&dev->device_lock);
+	spin_unlock(&file_ext->file_lock);
 	err = wait_event_timeout(dev->wait_recvd_msg,
 			(HECI_FILE_CONNECTED == file_ext->state
 			 || HECI_FILE_DISCONNECTED == file_ext->state),
-- 
1.6.0.rc1

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