svn commit: r230125 - head/sys/kern

[Eitan Adler]

On Tue, Jan 17, 2012 at 10:08 AM, John Baldwin <jhb at freebsd.org> wrote:
> On Sunday, January 15, 2012 6:32:43 pm Colin Percival wrote:
>> On 01/15/12 15:28, John Baldwin wrote:
>> > On 1/15/12 2:09 AM, Eitan Adler wrote:
>> >> Log:
>> >>    - Fix undefined behavior when device_get_name is null
>> >>    - Make error message more informative
>> >
>> > The in-kernel printf(9) always prints "(null)" for %s when the pointer is NULL,
>> > so that wasn't undefined behavior.  Printing out the driver name is a useful
>> > change, but the "(unknown)" bits are just noise as it isn't clear that
>> > "(unknown)" is substantially better than "(null)".
>>
>> I think the change from "(null)" to "(unknown)" is useful, since when I see
>> "(null)" printed my immediate thought is "looks like there's a bug I need to
>> track down here".
>
> The entire printf is "there's a bug I need to track down here".  (null)
> explicitly tells me that device_get_name() is NULL when looking at the printf
> to see what it means.  Having it be (unknown) tells me the same exact thing,
> but only after I've parsed an extra 2-3 lines of code to figure out what
> (unknown) stands for.

To me seeing "(null)" from the output of printf indicates "There is a
bug here, printf should never be given a NULL argument.".
However, given that it isn't undefined here, and the objections I've
received I will revert this part of the change when I get home.


-- 
Eitan Adler
Ports committer
X11, Bugbusting teams