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From: Pavel Skripkin <paskripkin@gmail.com>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "Larry.Finger@lwfinger.net" <Larry.Finger@lwfinger.net>,
	"phil@philpotter.co.uk" <phil@philpotter.co.uk>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"straube.linux@gmail.com" <straube.linux@gmail.com>,
	"fmdefrancesco@gmail.com" <fmdefrancesco@gmail.com>,
	"linux-staging@lists.linux.dev" <linux-staging@lists.linux.dev>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 5/6] staging: r8188eu: add error handling of rtw_read32
Date: Thu, 26 Aug 2021 12:27:55 +0300	[thread overview]
Message-ID: <685618ac-8de1-4eb1-57dd-9d43b96e872e@gmail.com> (raw)
In-Reply-To: <20210826122221.5d2b0f37@gmail.com>

On 8/26/21 12:22 PM, Pavel Skripkin wrote:
> On Thu, 26 Aug 2021 08:51:23 +0000
> David Laight <David.Laight@ACULAB.COM> wrote:
> 
>> From: Pavel Skripkin <paskripkin@gmail.com>
>> > Sent: 24 August 2021 08:28
>> > 
>> > _rtw_read32 function can fail in case of usb transfer failure. But
>> > previous function prototype wasn't designed to return an error to
>> > caller. It can cause a lot uninit value bugs all across the driver
>> > code, since rtw_read32() returns local stack variable to caller.
>> > 
>> > Fix it by changing the prototype of this function. Now it returns an
>> > int: 0 on success, negative error value on failure and callers
>> > should pass the pointer to storage location for register value.
>> 
>> Pretty horrid API interface.
>> Functions like readl() - which can fail just return ~0u and let
>> the caller worry about whether that causes serious grief.
>> 
>> You could make all the read functions return __u64 and return ~0ull
>> on error.
>> Testing for (value & 1ull << 63) will be reasonable even on 32bit.
>> 
> 
> I am not the best at API related questions, so can you, please,
> explain why your approach is better?
> 
> As I can see, most of the drivers in usb/ directory use smth like this
> interface for private reading funcions. We anyway creating tmp variable
> (but 64 bit _always_) and checking for mistery error, which we cannot
> pass up to callers.
> 
> Sorry, if it's _too_ dumb question, but I really can't get your
> point....
> 
> 
> 
>   
> 
>> ...
>> > -static u32 usb_read32(struct intf_hdl *pintfhdl, u32 addr)
>> > +static int usb_read32(struct intf_hdl *pintfhdl, u32 addr, u32
>> > *data) {
>> >  	u8 requesttype;
>> >  	u16 wvalue;
>> >  	u16 len;
>> > -	__le32 data;
>> > +	int res;
>> > +	__le32 tmp;
>> > +
>> > +	if (WARN_ON(unlikely(!data)))
>> > +		return -EINVAL;
>> > 
>> 
>> Kill the NULL check - it is a silly coding error.
>> An OOPS is just as easy to debug.
>> 
> 
> 
> I don't think that one single driver should kill the whole system. It's
> 100% an error, but kernel can recover from it (for example disconnect
> the driver, since it's broken).
> 
> 
> AFIAK, Greg and Linus do not like BUG_ONs in recoverable state...
> Correct me, if I am wrong
> 
Oops, I thought about BUG_ON() instead of WARN_ON(), sorry for 
confusion. My point is "we should not let the box boom".





With regards,
Pavel Skripkin

  reply	other threads:[~2021-08-26  9:28 UTC|newest]

Thread overview: 118+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-20 17:07 [PATCH RFC 0/3] staging: r8188eu: avoid uninit value bugs 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 [this message]
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               ` [PATCH RFC 0/3] " Fabio M. De Francesco
2021-08-22 16:15                 ` Pavel Skripkin
2021-08-22 15:04             ` Phillip Potter

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