Re: [PATCH] netfilter: use per-cpu recursive lock (v13)

[Linus Torvalds]

On Tue, 21 Apr 2009, Stephen Hemminger wrote:
>
> This version of x_tables (ip/ip6/arp) locking uses a per-cpu
> recursive lock that can be nested.

Ack on the code.

But the comment is _still_ crap. Please update. It's not a recursive lock, 
as clearly shown by the code itself. It's a per-cpu read-write lock, and 
only the reader is "recursive" (but that's how read-write locks with in 
Linux, and that has nothing to do with anything).

So make the explanations match the code and the intent. Write it something 
like

	This version of x_tables (ip/ip6/arp) locking uses a per-cpu
	reader-writer lock lock where the readers can nest.

and don't confuse it with incorrect commit messages. The lock is very much 
not recursive - on purpose - for half the people taking it.

[ That, btw, was always true, even in the original random open-coded 
  version. Because you can't actually do a real recursive lock without 
  having notion of "current ownership" either by making the count be 
  <per-thread,per-lock> - like the BKL - or by saving the ownership 
  information in the lock. A plain counter simply doesn't do it. ]

		Linus
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