[Linux-kernel-mentees] [PATCH v2] nl80211: Fix undefined behavior in bit shift

Shuah Khan skhan at linuxfoundation.org
Fri Jun 28 15:04:16 UTC 2019

On 6/28/19 7:57 AM, Johannes Berg wrote:
> On Wed, 2019-06-26 at 21:34 -0600, Shuah Khan wrote:
>> On 6/26/19 9:25 PM, Jiunn Chang wrote:
>>> Shifting signed 32-bit value by 31 bits is undefined.  Changing most
>>> significant bit to unsigned.
>>> Changes included in v2:
>>>     - use subsystem specific subject lines
>>>     - CC required mailing lists
>>> Signed-off-by: Jiunn Chang <c0d1n61at3 at gmail.com>
>>> ---
>> Move version change lines here. They don't belong in the commit log.
> FWIW, in many cases people (maintainers) now *do* want them in the
> commit log. Here, they're just editorial, so agree, but if real
> technical changes were made due to reviews, they can indeed be useful.
> johannes

I went looking in the git log. Looks like there are several commits with
"Changes since" included in the commit log. It still appears to be
maintainer preference. Probably from networking and networking related
areas - wireless being one of them. This trend is recent it appears in
any case.

There is a value to seeing changes as the work evolves. However, there
is the concern that how log should it be.

This example commit has history from RFC stage and no doubt very useful
since this is a new driver.


If we make this more of a norm, we do want to make sure, we evolve
from informal nature of these "Changes since", to "Commit log" text.

-- Shuah

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