From: Shuah Khan <skhan@linuxfoundation.org>
To: Alan Stern <stern@rowland.harvard.edu>,
Hongren Zenithal Zheng <i@zenithal.me>
Cc: Rhett Aultman <rhett.aultman@samsara.com>,
linux-usb@vger.kernel.org, linux-can <linux-can@vger.kernel.org>,
Oliver Neukum <oneukum@suse.com>,
Marc Kleine-Budde <mkl@pengutronix.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
Shuah Khan <shuah@kernel.org>,
Shuah Khan <skhan@linuxfoundation.org>
Subject: Re: [PATCH v3 1/2] drivers: usb/core/urb: Add URB_FREE_COHERENT
Date: Mon, 1 Aug 2022 11:42:07 -0600 [thread overview]
Message-ID: <07e82270-cc75-d346-72cf-0a60ffba06dc@linuxfoundation.org> (raw)
In-Reply-To: <b18313ab-c408-83dc-ee96-a64a432fbfcb@linuxfoundation.org>
On 6/30/22 8:10 PM, Shuah Khan wrote:
> On 6/27/22 7:35 PM, Alan Stern wrote:
>> On Mon, Jun 27, 2022 at 04:54:17PM -0600, Shuah Khan wrote:
>>> On 6/24/22 12:07 PM, Alan Stern wrote:
>>>> In the future people will want to make other changes to
>>>> include/linux/usb.h and they will not be aware that those changes will
>>>> adversely affect usbip, because there is no documentation saying that
>>>> the values defined in usb.h are part of a user API. That will be a
>>>> problem, because those changes may be serious and important ones, not
>>>> just decorative or stylistic as in this case.
>>>>
>>>
>>> How often do these values change based on our past experience with these
>>> fields?
>>
>> I don't know. You could check the git history to find out for certain.
>> My guess would be every eight or ten years.
>>
>>>> I agree with Hongren that values defined in include/linux/ should not be
>>>> part of a user API. There are two choices:
>>>>
>>>
>>> I agree with this in general. I don't think this is an explicit decision
>>> to make them part of API. It is a consequence of simply copying the
>>> transfer_flags. I am with you both on not being able to recognize the
>>> impact until as this is rather obscure usage hidden away in the packets.
>>> These defines aren't directly referenced.
>>>
>>>> Move the definitions into include/uapi/linux/, or
>>>>
>>>
>>> Wouldn't this be easier way to handle the change? With this option
>>> the uapi will be well documented.
>>>
>>>> Add code to translate the values between the numbers used in
>>>> userspace and the numbers used in the kernel. (This is what
>>>> was done for urb->transfer_flags in devio.c:proc_do_submiturb()
>>>> near line 1862.)
>>>>
>>>
>>> I looked at the code and looks simple enough. I am okay going this route
>>> if we see issues with the option 1.
>>
>> It's up to you; either approach is okay with me. However, I do think
>> that the second option is a little better; I don't see any good reason
>> why the kernel should be forced to use the same numeric values for these
>> flags forever. Especially since the only user program that needs to
>> know them is usbip, which is fairly closely tied to the kernel; if there
>> were more programs using those values then they would constitute a good
>> reason for choosing the first option.
>>
>
> Thank you Alan and Hongren for your help with this problem. Since there
> are no changes to the flags for the time being, I am comfortable going
> with the second option.
>
> I will send a patch soon.
>
Patch is almost ready to be sent out. Changes aren't bad at all. Hoping to
get this done sooner - summer vacations didn't cooperate.
Just an update that I haven't forgotten and it will taken care of.
thanks,
-- Shuah
next prev parent reply other threads:[~2022-08-01 17:42 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-03 19:52 [PATCH 001/001] can: gs_usb: gs_usb_open/close( ) fix memory leak Rhett Aultman
2022-06-04 2:11 ` [PATCH] " Vincent Mailhol
2022-06-04 2:26 ` Vincent MAILHOL
2022-06-04 14:08 ` Rhett Aultman
2022-06-04 14:41 ` [RFC PATCH] USB: core: urb: add new transfer flag URB_FREE_COHERENT Vincent Mailhol
2022-06-04 16:40 ` Alan Stern
2022-06-05 2:04 ` Vincent MAILHOL
2022-06-05 6:00 ` Oliver Neukum
2022-06-05 13:45 ` Vincent MAILHOL
2022-06-07 9:49 ` Oliver Neukum
2022-06-07 10:18 ` Vincent MAILHOL
2022-06-07 11:46 ` Oliver Neukum
2022-06-07 12:12 ` Vincent MAILHOL
2022-06-05 2:15 ` [RFC PATCH v2] usb: " Vincent Mailhol
2022-06-04 14:53 ` [PATCH] can: gs_usb: gs_usb_open/close( ) fix memory leak Vincent MAILHOL
2022-06-09 20:47 ` [PATCH v2 0/3] URB_FREE_COHERENT gs_usb memory leak fix Rhett Aultman
2022-06-09 20:47 ` [PATCH v2 1/3] drivers: usb/core/urb: Add URB_FREE_COHERENT Rhett Aultman
2022-06-10 0:18 ` Vincent MAILHOL
2022-06-10 10:46 ` Marc Kleine-Budde
2022-06-09 20:47 ` [PATCH v2 2/3] drivers: usb/core/urb: allow URB_FREE_COHERENT Rhett Aultman
2022-06-09 23:18 ` Vincent Mailhol
2022-06-09 20:47 ` [PATCH v2 3/3] can: gs_usb: fix DMA memory leak on close Rhett Aultman
2022-06-10 0:05 ` Vincent Mailhol
2022-06-10 1:28 ` Vincent Mailhol
2022-06-10 21:33 ` [PATCH v3 0/2] URB_FREE_COHERENT gs_usb memory leak fix Rhett Aultman
2022-06-10 21:33 ` [PATCH v3 1/2] drivers: usb/core/urb: Add URB_FREE_COHERENT Rhett Aultman
2022-06-11 15:31 ` Marc Kleine-Budde
2022-06-11 16:06 ` Vincent MAILHOL
2022-06-21 13:51 ` Greg Kroah-Hartman
2022-06-21 14:59 ` Vincent MAILHOL
2022-06-21 15:03 ` Greg Kroah-Hartman
2022-06-21 15:54 ` Vincent MAILHOL
2022-06-21 15:11 ` Alan Stern
2022-06-21 15:55 ` Vincent MAILHOL
2022-06-21 16:14 ` Alan Stern
2022-06-21 16:40 ` Vincent MAILHOL
2022-06-21 17:00 ` Greg Kroah-Hartman
2022-06-21 17:14 ` Vincent MAILHOL
2022-06-21 17:46 ` Greg Kroah-Hartman
2022-06-22 9:22 ` David Laight
2022-06-22 9:41 ` Greg Kroah-Hartman
2022-06-22 10:03 ` David Laight
2022-06-22 11:11 ` Oliver Neukum
2022-06-22 10:34 ` Vincent MAILHOL
2022-06-22 12:23 ` Greg Kroah-Hartman
2022-06-22 15:59 ` Vincent MAILHOL
2022-06-22 18:11 ` Rhett Aultman
2022-06-26 8:21 ` Vincent MAILHOL
2022-06-27 19:24 ` Rhett Aultman
2022-06-28 1:09 ` Vincent MAILHOL
2022-07-04 13:02 ` Marc Kleine-Budde
2022-07-04 15:35 ` Rhett Aultman
2022-07-05 7:50 ` Marc Kleine-Budde
2022-06-23 17:30 ` Hongren Zenithal Zheng
2022-06-23 17:45 ` Shuah Khan
2022-06-24 14:43 ` Alan Stern
2022-06-24 16:01 ` Hongren Zenithal Zheng
2022-06-24 16:31 ` Shuah Khan
2022-06-24 18:07 ` Alan Stern
2022-06-27 22:54 ` Shuah Khan
2022-06-28 1:35 ` Alan Stern
2022-07-01 2:10 ` Shuah Khan
2022-08-01 17:42 ` Shuah Khan [this message]
2022-08-01 18:28 ` Vincent MAILHOL
2022-08-03 23:44 ` Shuah Khan
2022-06-10 21:33 ` [PATCH v3 2/2] can: gs_usb: fix DMA memory leak on close Rhett Aultman
2022-06-11 15:35 ` Marc Kleine-Budde
2022-06-11 16:03 ` Vincent MAILHOL
2022-06-12 21:28 ` David Laight
2022-06-12 21:33 ` Marc Kleine-Budde
2022-06-14 15:26 ` [PATCH v4 0/1] URB_FREE_COHERENT gs_usb memory leak fix Rhett Aultman
2022-06-14 15:26 ` [PATCH v4 1/1] can: gs_usb: fix DMA memory leak on close Rhett Aultman
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