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@xxxxxxxxxxxxx>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
---
drivers/misc/eeprom/at24.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 0b8fafdb..1f62aaf 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[] = {
--
2.7.4
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