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, 4 insertions, 3 deletions

diff --git a/drivers/i2c/i2c-boardinfo.c b/drivers/i2c/i2c-boardinfo.c
index ffb35f09df0..a26a34a0664 100644
--- a/drivers/i2c/i2c-boardinfo.c
+++ b/drivers/i2c/i2c-boardinfo.c
@@ -18,6 +18,7 @@
 
 #include <linux/kernel.h>
 #include <linux/i2c.h>
+#include <linux/rwsem.h>
 
 #include "i2c-core.h"
 
@@ -25,7 +26,7 @@
 /* These symbols are exported ONLY FOR the i2c core.
  * No other users will be supported.
  */
-DEFINE_MUTEX(__i2c_board_lock);
+DECLARE_RWSEM(__i2c_board_lock);
 EXPORT_SYMBOL_GPL(__i2c_board_lock);
 
 LIST_HEAD(__i2c_board_list);
@@ -63,7 +64,7 @@ i2c_register_board_info(int busnum,
 {
         int status;
 
-        mutex_lock(&__i2c_board_lock);
+        down_write(&__i2c_board_lock);
 
         /* dynamic bus numbers will be assigned after the last static one */
         if (busnum >= __i2c_first_dynamic_bus_num)
@@ -84,7 +85,7 @@ i2c_register_board_info(int busnum,
                 list_add_tail(&devinfo->list, &__i2c_board_list);
         }
 
-        mutex_unlock(&__i2c_board_lock);
+        up_write(&__i2c_board_lock);
 
         return status;
 }