lkml.org 
[lkml]   [2016]   [Jul]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] eeprom: at24: tweak the loop_until_timeout() macro
Date
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>
---
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
\
 
 \ /
  Last update: 2016-07-17 21:21    [W:0.033 / U:0.136 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site