linux-kernel - Re: [PATCH v3 01/17] hashtable: introduce a small and naive hashtable

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Message-ID: <5048D6DE.8090805@gmail.com>
Date:	Thu, 06 Sep 2012 19:01:18 +0200
From:	Sasha Levin <levinsasha928@...il.com>
To:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
CC:	Steven Rostedt <rostedt@...dmis.org>,
	Josh Triplett <josh@...htriplett.org>,
	Pedro Alves <palves@...hat.com>, Tejun Heo <tj@...nel.org>,
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Subject: Re: [PATCH v3 01/17] hashtable: introduce a small and naive hashtable

On 09/06/2012 06:50 PM, Mathieu Desnoyers wrote:
> * Sasha Levin (levinsasha928@...il.com) wrote:
>> On 09/06/2012 06:00 PM, Steven Rostedt wrote:
>>>>> I think that that code doesn't make sense. The users of hlist_for_each_* aren't
>>>>> supposed to be changing the loop cursor.
>>> I totally agree. Modifying the 'node' pointer is just asking for issues.
>>> Yes that is error prone, but not due to the double loop. It's due to the
>>> modifying of the node pointer that is used internally by the loop
>>> counter. Don't do that :-)
>>
>> While we're on this subject, I haven't actually seen hlist_for_each_entry() code
>> that even *touches* 'pos'.
>>
>> Will people yell at me loudly if I change the prototype of those macros to be:
>>
>> 	hlist_for_each_entry(tpos, head, member)
>>
>> (Dropping the 'pos' parameter), and updating anything that calls those macros to
>> drop it as well?
> 
> I think the intent there is to keep hlist macros and list macros
> slightly in sync. Given those are vastly used, I'm not sure you want to
> touch them. But hey, that's just my 2 cents.

Actually, the corresponding list macro looks like this:

	list_for_each_entry(pos, head, member)

With 'pos' being the equivalent of 'tpos' in the hlist macros (the type *).
Changing hlist macro will make them both look as follows:

	hlist_for_each_entry(pos, head, member)
	list_for_each_entry(pos, head, member)

So following this suggesting will actually bring them back to sync...

The only issue I can see is that as you've said, they're used almost everywhere,
so doing something to change that will require some coordination.


Thanks,
Sasha
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