[media] staging/cx25721: serialize access to devlist

Out of the three files accessing the device list,
one uses a mutex, one uses the BKL and one does
not have any locking. That is of course pointless,
so let's make all of them use the same mutex,
and get rid of one more BKL user.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Palash Bandyopadhyay <palash.bandyopadhyay@conexant.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/cx25821/Kconfig

@@ -1,7 +1,6 @@
 config VIDEO_CX25821
 	tristate "Conexant cx25821 support"
 	depends on DVB_CORE && VIDEO_DEV && PCI && I2C
-	depends on BKL # please fix
 	select I2C_ALGOBIT
 	select VIDEO_BTCX
 	select VIDEO_TVEEPROM

drivers/staging/cx25821/cx25821-alsa.c

@@ -770,10 +770,12 @@ static int cx25821_alsa_init(void)
 	struct cx25821_dev *dev = NULL;
 	struct list_head *list;
 
+	mutex_lock(&cx25821_devlist_mutex);
 	list_for_each(list, &cx25821_devlist) {
 		dev = list_entry(list, struct cx25821_dev, devlist);
 		cx25821_audio_initdev(dev);
 	}
+	mutex_unlock(&cx25821_devlist_mutex);
 
 	if (dev == NULL)
 		pr_info("ERROR ALSA: no cx25821 cards found\n");

drivers/staging/cx25821/cx25821-core.c

@@ -33,9 +33,6 @@ MODULE_DESCRIPTION("Driver for Athena cards");
 MODULE_AUTHOR("Shu Lin - Hiep Huynh");
 MODULE_LICENSE("GPL");
 
-struct list_head cx25821_devlist;
-EXPORT_SYMBOL(cx25821_devlist);
-
 static unsigned int debug;
 module_param(debug, int, 0644);
 MODULE_PARM_DESC(debug, "enable debug messages");
@@ -46,8 +43,10 @@ MODULE_PARM_DESC(card, "card type");
 
 static unsigned int cx25821_devcount;
 
-static DEFINE_MUTEX(devlist);
+DEFINE_MUTEX(cx25821_devlist_mutex);
+EXPORT_SYMBOL(cx25821_devlist_mutex);
 LIST_HEAD(cx25821_devlist);
+EXPORT_SYMBOL(cx25821_devlist);
 
 struct sram_channel cx25821_sram_channels[] = {
 	[SRAM_CH00] = {
@@ -911,9 +910,9 @@ static int cx25821_dev_setup(struct cx25821_dev *dev)
 	dev->nr = ++cx25821_devcount;
 	sprintf(dev->name, "cx25821[%d]", dev->nr);
 
-	mutex_lock(&devlist);
+	mutex_lock(&cx25821_devlist_mutex);
 	list_add_tail(&dev->devlist, &cx25821_devlist);
-	mutex_unlock(&devlist);
+	mutex_unlock(&cx25821_devlist_mutex);
 
 	strcpy(cx25821_boards[UNKNOWN_BOARD].name, "unknown");
 	strcpy(cx25821_boards[CX25821_BOARD].name, "cx25821");
@@ -1465,9 +1464,9 @@ static void __devexit cx25821_finidev(struct pci_dev *pci_dev)
 	if (pci_dev->irq)
 		free_irq(pci_dev->irq, dev);
 
-	mutex_lock(&devlist);
+	mutex_lock(&cx25821_devlist_mutex);
 	list_del(&dev->devlist);
-	mutex_unlock(&devlist);
+	mutex_unlock(&cx25821_devlist_mutex);
 
 	cx25821_dev_unregister(dev);
 	v4l2_device_unregister(v4l2_dev);
@@ -1501,7 +1500,6 @@ static struct pci_driver cx25821_pci_driver = {
 
 static int __init cx25821_init(void)
 {
-	INIT_LIST_HEAD(&cx25821_devlist);
 	pr_info("driver version %d.%d.%d loaded\n",
 		(CX25821_VERSION_CODE >> 16) & 0xff,
 		(CX25821_VERSION_CODE >> 8) & 0xff,

drivers/staging/cx25821/cx25821-video.c

@@ -27,7 +27,6 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include "cx25821-video.h"
-#include <linux/smp_lock.h>
 
 MODULE_DESCRIPTION("v4l2 driver module for cx25821 based TV cards");
 MODULE_AUTHOR("Hiep Huynh <hiep.huynh@conexant.com>");
@@ -815,7 +814,7 @@ static int video_open(struct file *file)
        if (NULL == fh)
 	       return -ENOMEM;
 
-       lock_kernel();
+	mutex_lock(&cx25821_devlist_mutex);
 
        list_for_each(list, &cx25821_devlist)
        {
@@ -832,8 +831,8 @@ static int video_open(struct file *file)
        }
 
        if (NULL == dev) {
-	       unlock_kernel();
+		mutex_unlock(&cx25821_devlist_mutex);
-	       return -ENODEV;
+		return -ENODEV;
        }
 
        file->private_data = fh;
@@ -862,7 +861,7 @@ static int video_open(struct file *file)
 			      sizeof(struct cx25821_buffer), fh, NULL);
 
        dprintk(1, "post videobuf_queue_init()\n");
-       unlock_kernel();
+	mutex_unlock(&cx25821_devlist_mutex);
 
        return 0;
 }

drivers/staging/cx25821/cx25821.h

@@ -31,7 +31,6 @@
 #include <linux/delay.h>
 #include <linux/sched.h>
 #include <linux/kdev_t.h>
-#include <linux/smp_lock.h>
 
 #include <media/v4l2-common.h>
 #include <media/v4l2-device.h>
@@ -445,6 +444,8 @@ static inline struct cx25821_dev *get_cx25821(struct v4l2_device *v4l2_dev)
 	v4l2_device_call_all(&dev->v4l2_dev, 0, o, f, ##args)
 
 extern struct list_head cx25821_devlist;
+extern struct mutex cx25821_devlist_mutex;
+
 extern struct cx25821_board cx25821_boards[];
 extern struct cx25821_subid cx25821_subids[];