From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bartosz Golaszewski Subject: [PATCH] eeprom: at24: tweak the loop_until_timeout() macro Date: Sun, 17 Jul 2016 20:40:06 +0200 Message-ID: <1468780806-13034-1-git-send-email-bgolaszewski@baylibre.com> Return-path: Received: from mail-wm0-f42.google.com ([74.125.82.42]:37728 "EHLO mail-wm0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751138AbcGQSkM (ORCPT ); Sun, 17 Jul 2016 14:40:12 -0400 Received: by mail-wm0-f42.google.com with SMTP id i5so89887141wmg.0 for ; Sun, 17 Jul 2016 11:40:11 -0700 (PDT) Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Wolfram Sang , linux-i2c , LKML , Andrew Lunn , Srinivas Kandagatla , Maxime Ripard , GregKH Cc: Bartosz Golaszewski 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 Signed-off-by: Bartosz Golaszewski --- 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