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authorBartosz Golaszewski <bgolaszewski@baylibre.com>2016-07-17 20:40:06 +0200
committerWolfram Sang <wsa@the-dreams.de>2016-07-18 20:07:54 +0200
commit24da3cc0e25f48e12656226e5ed313573a3b443f (patch)
tree5ad5a9441d18e625b54678481c3ad80740c9d7d2 /drivers/misc
parent0b813658c11532be90cbf5f579a8ba45a8cc9dbf (diff)
eeprom: at24: tweak the loop_until_timeout() macro
loop_until_timeout() replaced a do {} while loop in the at24 driver with a for loop which, under certain circumstances (such as heavy load or low value of the write_timeout argument), can lead to the code in the loop never being executed. Make sure that at least one iteration of the code enclosed within loop_until_timeout() is always executed. Suggested-by: Wolfram Sang <wsa@the-dreams.de> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/misc')
-rw-r--r--drivers/misc/eeprom/at24.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 04e91e331fc5..3cdf8e1ca0ad 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -116,7 +116,8 @@ MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
/*
* Both reads and writes fail if the previous write didn't complete yet. This
* macro loops a few times waiting at least long enough for one entire page
- * write to work.
+ * write to work while making sure that at least one iteration is run before
+ * checking the break condition.
*
* It takes two parameters: a variable in which the future timeout in jiffies
* will be stored and a temporary variable holding the time of the last
@@ -124,9 +125,8 @@ MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
* holding at least 32 bits.
*/
#define loop_until_timeout(tout, op_time) \
- for (tout = jiffies + msecs_to_jiffies(write_timeout), \
- op_time = jiffies; \
- time_before(op_time, tout); \
+ for (tout = jiffies + msecs_to_jiffies(write_timeout), op_time = 0; \
+ op_time ? time_before(op_time, tout) : true; \
usleep_range(1000, 1500), op_time = jiffies)
static const struct i2c_device_id at24_ids[] = {