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From: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To: Greg KH <gregkh@linuxfoundation.org>,
	Pavel Skripkin <paskripkin@gmail.com>
Cc: Larry.Finger@lwfinger.net, phil@philpotter.co.uk,
	straube.linux@gmail.com, linux-staging@lists.linux.dev,
	linux-kernel@vger.kernel.org, Martin Kaiser <martin@kaiser.cx>
Subject: Re: [PATCH RFC 0/3] staging: r8188eu: avoid uninit value bugs
Date: Sun, 22 Aug 2021 18:03:07 +0200	[thread overview]
Message-ID: <23968040.bvS6LFdsLj@localhost.localdomain> (raw)
In-Reply-To: <6182ed46-d79d-7f66-c7c0-096486410b4d@gmail.com>

On Sunday, August 22, 2021 3:31:31 PM CEST Pavel Skripkin wrote:
> On 8/22/21 4:21 PM, Fabio M. De Francesco wrote:
> > On Sunday, August 22, 2021 2:39:34 PM CEST Greg KH wrote:
> >> On Sun, Aug 22, 2021 at 03:10:56PM +0300, Pavel Skripkin wrote:
> >> > On 8/22/21 1:59 PM, Fabio M. De Francesco wrote:
> >> > > On Sunday, August 22, 2021 12:09:29 PM CEST Pavel Skripkin wrote:
> > [...]
> >> > > So, it's up to the callers to test if (!_rtw_read*()) and then act
> >> > > accordingly. If they get 0 they should know how to handle the errors.
> >> > 
> >> > Yes, but _rtw_read*() == 0 indicates 2 states:
> >> > 	1. Error on transfer side
> >> > 	2. Actual register value is 0
> >> 
> >> That's not a good design, it should be fixed.  Note there is the new
> >> usb_control_msg_recv() function which should probably be used instead
> >> here, to prevent this problem from happening.
> > 
> > I think that no functions should return 0 for signaling FAILURE. If I'm not
> > wrong, the kernel quite always prefers to return 0 on SUCCESS and <0 on
> > FAILURE. Why don't you just fix this?
> > 
> That's what I've done in v2. All rtw_read* family will have following 
> prototype in v2:
> 
> int __must_check _rtw_read8(struct adapter *adapter, u32 addr, u8 *data);
> 
> Was it your idea, or you were talking about different approach?
> 
> With regards,
> Pavel Skripkin

Pavel,

Yes, it is correct.

However, after that I had time to look at the calls chain and understand what 
each function does and then I saw that my initial proposal should be made
along with another one...

The calls chain is:

(1)        _rtw_read8()  <--- (returns the data read from next function in chain) 
                                            (no errors returned, see possible fix in next function)
(2)                usb_read8() <--- (returns the data read from next function in chain) 
                                                 (_data_may_be_unitialised_, no errors returned)
		  (possible fix: from "u8 data"; to "char data = -1;")
(3)                           usbctrl_vendorreq() <---- (returns data read from next function in chain)
		                            (data is always a valid pointer saved to third argument)
		                            (if it fails, the third argument is unchanged because it
		                            still has the address of the "data" argument given by the caller)
(4)	                usb_control_msg() <---- (it always returns how many bytes read or valid error codes)
		                                  (it _never_ returns 0: either positive or negative values)
		
I have not yet looked at the usb_control_msg_recv() which Greg talked about.

To summarize: in function (2) "u8 data" should become "char data = -1;".

Regards,

Fabio

P.S.: I was about to send this message while I see that you sent v2. Since I've already have
this response to your question I send it and soon after I'm going to read your v2 patches. 
 





  parent reply	other threads:[~2021-08-22 16:03 UTC|newest]

Thread overview: 118+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-20 17:07 Pavel Skripkin
2021-08-20 17:07 ` [PATCH RFC 1/3] staging: r8188eu: add proper rtw_read* error handling Pavel Skripkin
2021-08-20 21:50   ` Pavel Skripkin
2021-08-20 23:41   ` Phillip Potter
2021-08-21  5:55   ` Fabio M. De Francesco
2021-08-21 10:35     ` Pavel Skripkin
2021-08-21 12:11       ` Fabio M. De Francesco
2021-08-20 17:07 ` [PATCH RFC 2/3] staging: r8188eu: add error handling to ReadFuse Pavel Skripkin
2021-08-20 23:51   ` Phillip Potter
2021-08-21  3:59     ` Fabio M. De Francesco
2021-08-20 17:07 ` [PATCH RFC 3/3] staging: r8188eu: add error argument to read_macreg Pavel Skripkin
2021-08-20 23:18   ` Phillip Potter
2021-08-21 10:38     ` Pavel Skripkin
2021-08-20 23:12 ` [PATCH RFC 0/3] staging: r8188eu: avoid uninit value bugs Phillip Potter
2021-08-21 10:42   ` Pavel Skripkin
2021-08-22  9:53 ` Fabio M. De Francesco
2021-08-22 10:09   ` Pavel Skripkin
2021-08-22 10:59     ` Fabio M. De Francesco
2021-08-22 11:34       ` Fabio M. De Francesco
2021-08-22 12:10       ` Pavel Skripkin
2021-08-22 12:39         ` Greg KH
2021-08-22 12:50           ` Pavel Skripkin
2021-08-22 13:06             ` Greg KH
2021-08-22 13:21           ` Fabio M. De Francesco
2021-08-22 13:30             ` Greg KH
2021-08-22 13:31             ` Pavel Skripkin
2021-08-22 14:35               ` [PATCH RFC v2 0/6] " Pavel Skripkin
2021-08-22 14:35                 ` [PATCH RFC v2 1/6] staging: r8188eu: remove {read,write}_macreg Pavel Skripkin
2021-08-22 14:35                 ` [PATCH RFC v2 2/6] staging: r8188eu: add helper macro for printing registers Pavel Skripkin
2021-08-22 14:35                 ` [PATCH RFC v2 3/6] staging: r8188eu: add error handling of rtw_read8 Pavel Skripkin
2021-08-22 14:35                 ` [PATCH RFC v2 4/6] staging: r8188eu: add error handling of rtw_read16 Pavel Skripkin
2021-08-22 14:36                 ` [PATCH RFC v2 5/6] staging: r8188eu: add error handling of rtw_read32 Pavel Skripkin
2021-08-23 23:33                   ` Phillip Potter
2021-08-24  0:10                     ` Fabio M. De Francesco
2021-08-24  6:40                       ` Pavel Skripkin
2021-08-24  8:38                         ` Fabio M. De Francesco
2021-08-24  8:47                           ` Pavel Skripkin
2021-08-24  8:53                             ` Pavel Skripkin
2021-08-24  9:46                               ` Fabio M. De Francesco
2021-08-24 22:10                               ` Phillip Potter
2021-08-24 22:07                             ` Phillip Potter
2021-08-24  6:53                     ` Pavel Skripkin
2021-08-24  7:25                     ` [PATCH v3 0/6] staging: r8188eu: avoid uninit value bugs Pavel Skripkin
2021-08-24  7:27                       ` [PATCH v3 1/6] staging: r8188eu: remove {read,write}_macreg Pavel Skripkin
2021-08-26 10:39                         ` Greg KH
2021-08-26 10:40                         ` Greg KH
2021-08-24  7:27                       ` [PATCH v3 2/6] staging: r8188eu: add helper macro for printing registers Pavel Skripkin
2021-08-26 10:37                         ` Greg KH
2021-08-24  7:27                       ` [PATCH v3 3/6] staging: r8188eu: add error handling of rtw_read8 Pavel Skripkin
2021-08-25 12:05                         ` kernel test robot
2021-08-25 12:17                           ` Pavel Skripkin
2021-08-25 12:51                             ` Dan Carpenter
2021-08-25 13:02                               ` Pavel Skripkin
2021-08-25 13:34                                 ` Dan Carpenter
2021-08-25 13:44                                   ` Pavel Skripkin
2021-08-25 17:11                                     ` Nick Desaulniers
2021-08-26 11:08                                       ` Dan Carpenter
2021-08-25 23:45                         ` Fabio M. De Francesco
2021-08-26  5:13                           ` Pavel Skripkin
2021-08-26  8:21                         ` David Laight
2021-08-26  8:27                           ` Pavel Skripkin
2021-08-26 10:19                             ` David Laight
2021-08-26 11:21                               ` Dan Carpenter
2021-08-27  8:14                                 ` David Laight
2021-08-27  8:22                                   ` Pavel Skripkin
2021-08-27  9:07                         ` Dan Carpenter
2021-08-27  9:16                           ` Pavel Skripkin
2021-08-27  9:23                             ` Dan Carpenter
2021-08-30 11:21                         ` kernel test robot
2021-08-24  7:27                       ` [PATCH v3 4/6] staging: r8188eu: add error handling of rtw_read16 Pavel Skripkin
2021-08-25  4:35                         ` Fabio M. De Francesco
2021-08-25  8:22                           ` Pavel Skripkin
2021-08-25  9:48                             ` Fabio M. De Francesco
2021-08-25  9:55                               ` Pavel Skripkin
2021-08-25 10:06                                 ` Dan Carpenter
2021-08-25 10:13                                   ` Pavel Skripkin
2021-08-25 10:38                                     ` Dan Carpenter
2021-08-25 10:41                                       ` Pavel Skripkin
2021-08-25 11:06                                       ` Fabio M. De Francesco
2021-08-25 11:11                                         ` Fabio M. De Francesco
2021-08-25 11:31                                         ` Dan Carpenter
2021-08-25 12:11                                           ` Fabio M. De Francesco
2021-08-25 10:51                                 ` Fabio M. De Francesco
2021-08-26 10:50                         ` Greg KH
2021-08-26 10:58                           ` Pavel Skripkin
2021-08-24  7:27                       ` [PATCH v3 5/6] staging: r8188eu: add error handling of rtw_read32 Pavel Skripkin
2021-08-25  4:40                         ` Fabio M. De Francesco
2021-08-26  8:51                         ` David Laight
2021-08-26  9:22                           ` Pavel Skripkin
2021-08-26  9:27                             ` Pavel Skripkin
2021-08-26 10:22                               ` David Laight
2021-08-26 10:55                                 ` Pavel Skripkin
2021-08-26 10:59                                   ` David Laight
2021-08-26 20:03                                     ` Pavel Skripkin
2021-08-27  7:12                                       ` gregkh
2021-08-27  7:16                                         ` Pavel Skripkin
2021-08-24  7:27                       ` [PATCH v3 6/6] staging: r8188eu: make ReadEFuse return an int Pavel Skripkin
2021-08-25 10:13                       ` [PATCH v3 0/6] staging: r8188eu: avoid uninit value bugs Fabio M. De Francesco
2021-08-27  7:49                       ` Kari Argillander
2021-08-27  7:52                         ` Pavel Skripkin
2021-08-24  6:58                   ` [PATCH RFC v2 5/6] staging: r8188eu: add error handling of rtw_read32 Dan Carpenter
2021-08-24  7:01                     ` Pavel Skripkin
2021-08-24 15:07                       ` Fabio M. De Francesco
2021-08-22 14:36                 ` [PATCH RFC v2 6/6] staging: r8188eu: make ReadEFuse return an int Pavel Skripkin
2021-08-22 15:30                 ` [PATCH RFC v2 0/6] staging: r8188eu: avoid uninit value bugs Pavel Skripkin
2021-08-22 16:05                   ` Michael Straube
2021-08-22 16:26                     ` Pavel Skripkin
2021-08-22 23:52                       ` Phillip Potter
2021-08-22 17:36                 ` Fabio M. De Francesco
2021-08-22 17:38                   ` Pavel Skripkin
2021-08-22 20:06                     ` Fabio M. De Francesco
2021-08-22 20:19                       ` Pavel Skripkin
2021-08-23  0:12                 ` Phillip Potter
2021-08-23  6:38                   ` Pavel Skripkin
2021-08-23  6:44                   ` Pavel Skripkin
2021-08-22 16:03               ` Fabio M. De Francesco [this message]
2021-08-22 16:15                 ` [PATCH RFC 0/3] " Pavel Skripkin
2021-08-22 15:04             ` Phillip Potter

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