Commit f18c41daea14baee11252da268cdf5dcd57c7c10
Committed by
Jean Delvare
Jean Delvare
1 parent
99cd8e2587
Exists in
master
and in
39 other branches
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>
Showing 3 changed files with 10 additions and 6 deletions Side-by-side Diff
drivers/i2c/i2c-boardinfo.c
| ... | ... | @@ -18,6 +18,7 @@ |
| 18 | 18 | |
| 19 | 19 | #include <linux/kernel.h> |
| 20 | 20 | #include <linux/i2c.h> |
| 21 | +#include <linux/rwsem.h> | |
| 21 | 22 | |
| 22 | 23 | #include "i2c-core.h" |
| 23 | 24 | |
| ... | ... | @@ -25,7 +26,7 @@ |
| 25 | 26 | /* These symbols are exported ONLY FOR the i2c core. |
| 26 | 27 | * No other users will be supported. |
| 27 | 28 | */ |
| 28 | -DEFINE_MUTEX(__i2c_board_lock); | |
| 29 | +DECLARE_RWSEM(__i2c_board_lock); | |
| 29 | 30 | EXPORT_SYMBOL_GPL(__i2c_board_lock); |
| 30 | 31 | |
| 31 | 32 | LIST_HEAD(__i2c_board_list); |
| ... | ... | @@ -63,7 +64,7 @@ |
| 63 | 64 | { |
| 64 | 65 | int status; |
| 65 | 66 | |
| 66 | - mutex_lock(&__i2c_board_lock); | |
| 67 | + down_write(&__i2c_board_lock); | |
| 67 | 68 | |
| 68 | 69 | /* dynamic bus numbers will be assigned after the last static one */ |
| 69 | 70 | if (busnum >= __i2c_first_dynamic_bus_num) |
| ... | ... | @@ -84,7 +85,7 @@ |
| 84 | 85 | list_add_tail(&devinfo->list, &__i2c_board_list); |
| 85 | 86 | } |
| 86 | 87 | |
| 87 | - mutex_unlock(&__i2c_board_lock); | |
| 88 | + up_write(&__i2c_board_lock); | |
| 88 | 89 | |
| 89 | 90 | return status; |
| 90 | 91 | } |
drivers/i2c/i2c-core.c
| ... | ... | @@ -33,6 +33,7 @@ |
| 33 | 33 | #include <linux/completion.h> |
| 34 | 34 | #include <linux/hardirq.h> |
| 35 | 35 | #include <linux/irqflags.h> |
| 36 | +#include <linux/rwsem.h> | |
| 36 | 37 | #include <asm/uaccess.h> |
| 37 | 38 | |
| 38 | 39 | #include "i2c-core.h" |
| ... | ... | @@ -509,7 +510,7 @@ |
| 509 | 510 | { |
| 510 | 511 | struct i2c_devinfo *devinfo; |
| 511 | 512 | |
| 512 | - mutex_lock(&__i2c_board_lock); | |
| 513 | + down_read(&__i2c_board_lock); | |
| 513 | 514 | list_for_each_entry(devinfo, &__i2c_board_list, list) { |
| 514 | 515 | if (devinfo->busnum == adapter->nr |
| 515 | 516 | && !i2c_new_device(adapter, |
| ... | ... | @@ -518,7 +519,7 @@ |
| 518 | 519 | "Can't create device at 0x%02x\n", |
| 519 | 520 | devinfo->board_info.addr); |
| 520 | 521 | } |
| 521 | - mutex_unlock(&__i2c_board_lock); | |
| 522 | + up_read(&__i2c_board_lock); | |
| 522 | 523 | } |
| 523 | 524 | |
| 524 | 525 | static int i2c_do_add_adapter(struct device_driver *d, void *data) |
drivers/i2c/i2c-core.h
| ... | ... | @@ -16,6 +16,8 @@ |
| 16 | 16 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| 17 | 17 | */ |
| 18 | 18 | |
| 19 | +#include <linux/rwsem.h> | |
| 20 | + | |
| 19 | 21 | struct i2c_devinfo { |
| 20 | 22 | struct list_head list; |
| 21 | 23 | int busnum; |
| ... | ... | @@ -25,7 +27,7 @@ |
| 25 | 27 | /* board_lock protects board_list and first_dynamic_bus_num. |
| 26 | 28 | * only i2c core components are allowed to use these symbols. |
| 27 | 29 | */ |
| 28 | -extern struct mutex __i2c_board_lock; | |
| 30 | +extern struct rw_semaphore __i2c_board_lock; | |
| 29 | 31 | extern struct list_head __i2c_board_list; |
| 30 | 32 | extern int __i2c_first_dynamic_bus_num; |