Re: mfd: Support 88pm80x in 80x driver

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On 05/18/2015 05:23 PM, Lee Jones wrote:
On Fri, 15 May 2015, Qiao Zhou wrote:

On 05/14/2015 08:50 PM, Lee Jones wrote:
On Thu, 14 May 2015, Qiao Zhou wrote:

On 05/14/2015 06:31 PM, Dan Carpenter wrote:
Hello Qiao Zhou,

The patch 70c6cce04066: "mfd: Support 88pm80x in 80x driver" from Jul
9, 2012, leads to the following static checker warning:

	include/linux/mfd/88pm80x.h:352 pm80x_dev_suspend()
	warn: test_bit() takes a bit number

include/linux/mfd/88pm80x.h
    344  #ifdef CONFIG_PM
    345  static inline int pm80x_dev_suspend(struct device *dev)
    346  {
    347          struct platform_device *pdev = to_platform_device(dev);
    348          struct pm80x_chip *chip = dev_get_drvdata(pdev->dev.parent);
    349          int irq = platform_get_irq(pdev, 0);
    350
    351          if (device_may_wakeup(dev))
    352                  set_bit((1 << irq), &chip->wu_flag);
                                 ^^^^^^^^^
Smatch is complaining because it's doing a double left shift.  If irq is
larger than 5 then we are corrupting memory.  Also we don't use
Will fix this issue.
->wu_flag as a bitfield, we use it as a boolean so the name is
confusing.

    353
    354          return 0;
    355  }
    356
    357  static inline int pm80x_dev_resume(struct device *dev)
    358  {
    359          struct platform_device *pdev = to_platform_device(dev);
    360          struct pm80x_chip *chip = dev_get_drvdata(pdev->dev.parent);
    361          int irq = platform_get_irq(pdev, 0);
    362
    363          if (device_may_wakeup(dev))
    364                  clear_bit((1 << irq), &chip->wu_flag);
                                   ^^^^^^^^^^
Same issue.

    365
    366          return 0;
    367  }
    368  #endif

drivers/mfd/88pm80x.c
    133  #ifdef CONFIG_PM_SLEEP
    134  static int pm80x_suspend(struct device *dev)
    135  {
    136          struct i2c_client *client = container_of(dev, struct i2c_client, dev);
    137          struct pm80x_chip *chip = i2c_get_clientdata(client);
    138
    139          if (chip && chip->wu_flag)
                             ^^^^^^^^^^^^^
Here it is used as a bool.
It's designed in this way that sub device driver may use this flag.
Also the bit value can tell which sub device sets the flag. However
here we just check whether any bit is set.
    140                  if (device_may_wakeup(chip->dev))
    141                          enable_irq_wake(chip->irq);
    142
    143          return 0;
    144  }
    145
    146  static int pm80x_resume(struct device *dev)
    147  {
    148          struct i2c_client *client = container_of(dev, struct i2c_client, dev);
    149          struct pm80x_chip *chip = i2c_get_clientdata(client);
    150
    151          if (chip && chip->wu_flag)
                             ^^^^^^^^^^^^^
This is the only other user.

    152                  if (device_may_wakeup(chip->dev))
    153                          disable_irq_wake(chip->irq);
    154
    155          return 0;
    156  }
    157  #endif


regards,
dan carpenter

Dan,

Below is the patch to fix this issue. Please have a check and I'll
submit an official patch to community after you reviewed. Thanks for
finding this issue.

 From 96486fda25414e3b926c275b951ac1408fae7830 Mon Sep 17 00:00:00 2001
From: Qiao Zhou <zhouqiao@xxxxxxxxxxx>
Date: Thu, 14 May 2015 19:00:39 +0800
Subject: [PATCH] mfd: 88pm80x: refine irq bit operation

Set_bit/clear_bit for wu_flag may be corrupted if irq > 5(or 6 for
aarch64). The maximum irq number from 88pm80x chip series is 24.
Here we refine the code to protect the potential memory corruption.

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Qiao Zhou <zhouqiao@xxxxxxxxxxx>
---
  include/linux/mfd/88pm80x.h |   16 ++++++++++++++--
  1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/include/linux/mfd/88pm80x.h b/include/linux/mfd/88pm80x.h
index 97cb283..a8c0318 100644
--- a/include/linux/mfd/88pm80x.h
+++ b/include/linux/mfd/88pm80x.h
[...]

  	if (device_may_wakeup(dev))
-		set_bit((1 << irq), &chip->wu_flag);
+		set_bit(irq, &chip->wu_flag);
Can you come up with a better name?
It's short for wakeup flag. I may change it to wakeup_flag. Do you
have any suggestion if it's not okay?
bool wakeup; will be fine.
Would it be OK to only change the same? The original purpose to use bit control is that MFD driver may check the bits so that it knows which sub-dev is doing something special. However, it's not pushed into mainline yet. Another concern is that Currently I've no
platform to verify the change to change the variable type.

Sorry for late response. I've been trapped in some urgent issues these days.

--
Best Regards
Qiao

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