Re: [PATCH] block: fix block_class iteration locking

From: Cornelia Huck
Date: Mon Jul 21 2008 - 13:55:26 EST

On Mon, 14 Jul 2008 20:50:57 +0900,
Tejun Heo <tj@xxxxxxxxxx> wrote:

> > With your patch, you protect against adding/removing devices to/from
> > the class between _start and _stop. This wasn't done previously, and
> > won't be done with Greg's patches (which leaves in the
> > locking/unlocking of block_class_lock). Not sure if I'm missing
> > something here...
> That's mostly the point of this patch. It wasn't protected properly
> before. It would be best if there's a safe iterator (maybe use klist?).

Hm, I don't see how a klist would help here since it still allows to
add/remove devices during walking the file.

What we need is more like a "lock/unlock the device list" operation and
a lockless iterator - that would give the same semantics as your patch.
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