i2c: Use rwsem instead of mutex for board info

By using rwsem we can easily manage recursive calls of
i2c_scan_static_board_info() function without breaking the locking.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index eb084fa0df83..0e45c296d3d2 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -33,6 +33,7 @@
 #include <linux/completion.h>
 #include <linux/hardirq.h>
 #include <linux/irqflags.h>
+#include <linux/rwsem.h>
 #include <asm/uaccess.h>
 
 #include "i2c-core.h"
@@ -509,7 +510,7 @@ static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
 {
         struct i2c_devinfo      *devinfo;
 
-        mutex_lock(&__i2c_board_lock);
+        down_read(&__i2c_board_lock);
         list_for_each_entry(devinfo, &__i2c_board_list, list) {
                 if (devinfo->busnum == adapter->nr
                                 && !i2c_new_device(adapter,
@@ -518,7 +519,7 @@ static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
                                 "Can't create device at 0x%02x\n",
                                 devinfo->board_info.addr);
         }
-        mutex_unlock(&__i2c_board_lock);
+        up_read(&__i2c_board_lock);
 }
 
 static int i2c_do_add_adapter(struct device_driver *d, void *data)