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Commit f18c41da authored by Rodolfo Giometti's avatar Rodolfo Giometti Committed by Jean Delvare
Browse files

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: default avatarRodolfo Giometti <giometti@linux.it>
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 99cd8e25

drivers/i2c/i2c-boardinfo.c

+4 −3
Original line number Original line Diff line number Diff line
@@ -18,6 +18,7 @@ 




#include <linux/kernel.h>

#include <linux/kernel.h>

#include <linux/i2c.h>

#include <linux/i2c.h>

#include <linux/rwsem.h>





#include "i2c-core.h"

#include "i2c-core.h"
@@ -25,7 +26,7 @@ 
/* These symbols are exported ONLY FOR the i2c core.

/* These symbols are exported ONLY FOR the i2c core.

 * No other users will be supported.

 * No other users will be supported.

 */

 */

DEFINE_MUTEX(__i2c_board_lock);

DECLARE_RWSEM(__i2c_board_lock);

EXPORT_SYMBOL_GPL(__i2c_board_lock);

EXPORT_SYMBOL_GPL(__i2c_board_lock);





LIST_HEAD(__i2c_board_list);

LIST_HEAD(__i2c_board_list);
@@ -63,7 +64,7 @@ i2c_register_board_info(int busnum, 
{

{

	int status;

	int status;





	mutex_lock(&__i2c_board_lock);

	down_write(&__i2c_board_lock);





	/* dynamic bus numbers will be assigned after the last static one */

	/* dynamic bus numbers will be assigned after the last static one */

	if (busnum >= __i2c_first_dynamic_bus_num)

	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);

		list_add_tail(&devinfo->list, &__i2c_board_list);

	}

	}





	mutex_unlock(&__i2c_board_lock);

	up_write(&__i2c_board_lock);





	return status;

	return status;

}
 
}

drivers/i2c/i2c-core.c

+3 −2
Original line number Original line Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include <linux/completion.h>

#include <linux/completion.h>

#include <linux/hardirq.h>

#include <linux/hardirq.h>

#include <linux/irqflags.h>

#include <linux/irqflags.h>

#include <linux/rwsem.h>

#include <asm/uaccess.h>

#include <asm/uaccess.h>





#include "i2c-core.h"

#include "i2c-core.h"
@@ -509,7 +510,7 @@ static void i2c_scan_static_board_info(struct i2c_adapter *adapter) 
{

{

	struct i2c_devinfo	*devinfo;

	struct i2c_devinfo	*devinfo;





	mutex_lock(&__i2c_board_lock);

	down_read(&__i2c_board_lock);

	list_for_each_entry(devinfo, &__i2c_board_list, list) {

	list_for_each_entry(devinfo, &__i2c_board_list, list) {

		if (devinfo->busnum == adapter->nr

		if (devinfo->busnum == adapter->nr

				&& !i2c_new_device(adapter,

				&& !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",

				"Can't create device at 0x%02x\n",

				devinfo->board_info.addr);

				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)

static int i2c_do_add_adapter(struct device_driver *d, void *data)

drivers/i2c/i2c-core.h

+3 −1
Original line number Original line Diff line number Diff line
@@ -16,6 +16,8 @@ 
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 */

 */





#include <linux/rwsem.h>



struct i2c_devinfo {

struct i2c_devinfo {

	struct list_head	list;

	struct list_head	list;

	int			busnum;

	int			busnum;
@@ -25,7 +27,7 @@ struct i2c_devinfo { 
/* board_lock protects board_list and first_dynamic_bus_num.

/* board_lock protects board_list and first_dynamic_bus_num.

 * only i2c core components are allowed to use these symbols.

 * only i2c core components are allowed to use these symbols.

 */

 */

extern struct mutex	__i2c_board_lock;

extern struct rw_semaphore	__i2c_board_lock;

extern struct list_head	__i2c_board_list;

extern struct list_head	__i2c_board_list;

extern int		__i2c_first_dynamic_bus_num;

extern int		__i2c_first_dynamic_bus_num;