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Subject: Re: [PATCH RFC 1/3] staging: r8188eu: add proper rtw_read* error
 handling
To:     "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
        Larry.Finger@lwfinger.net, phil@philpotter.co.uk,
        gregkh@linuxfoundation.org, straube.linux@gmail.com
Cc:     linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
References: <cover.1629479152.git.paskripkin@gmail.com>
 <f4fb967c992c29c8d2e8f67e78835b52a60d2e52.1629479152.git.paskripkin@gmail.com>
 <5720270.rXTAdOU5UK@localhost.localdomain>
From:   Pavel Skripkin <paskripkin@gmail.com>
Message-ID: <31d61caa-d07d-193f-cd8e-adfbda1ff9e2@gmail.com>
Date:   Sat, 21 Aug 2021 13:35:48 +0300
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On 8/21/21 8:55 AM, Fabio M. De Francesco wrote:
> On Friday, August 20, 2021 7:07:36 PM CEST Pavel Skripkin wrote:
>> rtw_read*() functions call usb_read* inside. These functions could fail
>> in some cases; for example: failed to receive control message. These
>> cases should be handled to prevent uninit value bugs, since usb_read*
>> functions blindly return stack variable without checking if this value
>> _actualy_ initialized.
>> 
>> To achive it, all usb_read* and rtw_read*() argument list is expanded
> 
> Dear Pavel,
> 
> Please, achive --> achieve.
> 
>> with pointer to error and added error usbctrl_vendorreq() error checking.
>> If transfer is successful error will be initialized to 0 otherwise to
>> error returned from usb_control_msg().
>> 
>> To not break the build, added error checking for rtw_read*() call all
>> across the driver.
>> 
>> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
>> ---
>>  drivers/staging/r8188eu/core/rtw_debug.c      |  79 +++-
>>  drivers/staging/r8188eu/core/rtw_efuse.c      |  83 +++-
>>  drivers/staging/r8188eu/core/rtw_io.c         |  18 +-
>>  drivers/staging/r8188eu/core/rtw_mp.c         |  37 +-
>>  drivers/staging/r8188eu/core/rtw_mp_ioctl.c   |  20 +-
>>  drivers/staging/r8188eu/core/rtw_pwrctrl.c    |   6 +-
>>  drivers/staging/r8188eu/core/rtw_sreset.c     |   7 +-
>>  drivers/staging/r8188eu/hal/HalPwrSeqCmd.c    |   9 +-
>>  drivers/staging/r8188eu/hal/hal_com.c         |  22 +-
>>  drivers/staging/r8188eu/hal/odm_interface.c   |  12 +-
>>  drivers/staging/r8188eu/hal/rtl8188e_cmd.c    |  37 +-
>>  drivers/staging/r8188eu/hal/rtl8188e_dm.c     |   6 +-
>>  .../staging/r8188eu/hal/rtl8188e_hal_init.c   | 198 +++++++--
>>  drivers/staging/r8188eu/hal/rtl8188e_phycfg.c |  26 +-
>>  drivers/staging/r8188eu/hal/rtl8188e_sreset.c |  20 +-
>>  drivers/staging/r8188eu/hal/rtl8188eu_led.c   |  17 +-
>>  drivers/staging/r8188eu/hal/usb_halinit.c     | 394 ++++++++++++++----
>>  drivers/staging/r8188eu/hal/usb_ops_linux.c   |  16 +-
>>  drivers/staging/r8188eu/include/rtw_io.h      |  18 +-
>>  drivers/staging/r8188eu/os_dep/ioctl_linux.c  | 168 +++++---
>>  20 files changed, 941 insertions(+), 252 deletions(-)
> 

Hi, Fabio!


Thank you for feedback

> I agree with Philip: please, split this long patch. If I were you, I'd make
> one patch for each of the three rtw_read*() and a fourth patch for usb_read*().
> 

Make sense. Will fix in v2.

>> --- a/drivers/staging/r8188eu/core/rtw_io.c
>> +++ b/drivers/staging/r8188eu/core/rtw_io.c
>> @@ -34,44 +34,44 @@ jackson@realtek.com.tw
>>  #define rtw_cpu_to_le16(val)		cpu_to_le16(val)
>>  #define rtw_cpu_to_le32(val)		cpu_to_le32(val)
> 
> Not related to your patch, these macros are useless and misleading.
> 

Sorry, I don't get it. I didn't touch these macros, it's part of diffstat.

>> -u8 _rtw_read8(struct adapter *adapter, u32 addr)
>> +u8 _rtw_read8(struct adapter *adapter, u32 addr, int *error)
>>  {
>>  	u8 r_val;
>>  	struct io_priv *pio_priv = &adapter->iopriv;
>>  	struct	intf_hdl *pintfhdl = &pio_priv->intf;
>> -	u8 (*_read8)(struct intf_hdl *pintfhdl, u32 addr);
>> +	u8 (*_read8)(struct intf_hdl *pintfhdl, u32 addr, int *error);
>>  
>>  
>>  	_read8 = pintfhdl->io_ops._read8;
>> -	r_val = _read8(pintfhdl, addr);
>> +	r_val = _read8(pintfhdl, addr, error);
>>  
>>  	return r_val;
>>  }
> 
> I really don't like passing errors through arguments. Why don't you pass
> a storage location where the function save the byte read and instead use the
> return for errors? I think that this would result in a cleaner design. Furthermore,
> it is used everywhere in the kernel.
>    

Yep, this will be more cleaner, but I decided to receive some feedback 
first about the idea. If this error handling is really necessary, I will 
rework this approach :)


>> -u16 _rtw_read16(struct adapter *adapter, u32 addr)
>> +u16 _rtw_read16(struct adapter *adapter, u32 addr, int *error)
>>  {
>>  	u16 r_val;
>>  	struct io_priv *pio_priv = &adapter->iopriv;
>>  	struct	intf_hdl		*pintfhdl = &pio_priv->intf;
>> -	u16 (*_read16)(struct intf_hdl *pintfhdl, u32 addr);
>> +	u16 (*_read16)(struct intf_hdl *pintfhdl, u32 addr, int *error);
>>  
>>  	_read16 = pintfhdl->io_ops._read16;
>>  
>> -	r_val = _read16(pintfhdl, addr);
>> +	r_val = _read16(pintfhdl, addr, error);
>>  
>>  	return r_val;
>>  }
> 
> Same.
> 
>> -u32 _rtw_read32(struct adapter *adapter, u32 addr)
>> +u32 _rtw_read32(struct adapter *adapter, u32 addr, int *error)
>>  {
>>  	u32 r_val;
>>  	struct io_priv *pio_priv = &adapter->iopriv;
>>  	struct	intf_hdl		*pintfhdl = &pio_priv->intf;
>> -	u32	(*_read32)(struct intf_hdl *pintfhdl, u32 addr);
>> +	u32	(*_read32)(struct intf_hdl *pintfhdl, u32 addr, int *error);
>>  
>>  	_read32 = pintfhdl->io_ops._read32;
>>  
>> -	r_val = _read32(pintfhdl, addr);
>> +	r_val = _read32(pintfhdl, addr, error);
>>  
>>  	return r_val;
>>  }
> 
> Same.
> 
> I'm done for now: too many lines to read all at once :)
> 


With regards,
Pavel Skripkin