From: Jarek Poplawski <jarkao2@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Linux Netdev List <netdev@vger.kernel.org>
Subject: Re: [PATCH] inetpeer: optimizations
Date: Sun, 6 Dec 2009 21:18:24 +0100 [thread overview]
Message-ID: <20091206201824.GA4159@ami.dom.local> (raw)
In-Reply-To: <4B1BFEBF.60901@gmail.com>
On Sun, Dec 06, 2009 at 07:58:07PM +0100, Eric Dumazet wrote:
> Yes, you miss something. We are not working on a true reference count variable.
> (p is referenced in avl tree but there is no +1 count for this reference)
>
> Its more a usecount one, and p usecount can be 0 but p still in avl tree.
>
> Even if we are the thread (A) doing 1 -> 0 transition, other thread (B)
> can find p and perform the opposite 0 -> 1 transition.
>
> If (B) tries to unlink p before (A), it finds p already unlinked.
>
> Then (A) links into unused list, while refcnt is still 1
This last thing can happen now too, but as I wrote, my idea was wrong,
nevertheless.
Jarek P.
next prev parent reply other threads:[~2009-12-06 20:18 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-05 12:11 [PATCH] inetpeer: optimizations Eric Dumazet
2009-12-05 21:29 ` Jarek Poplawski
2009-12-06 8:47 ` Eric Dumazet
2009-12-06 14:18 ` Jarek Poplawski
2009-12-06 18:22 ` Jarek Poplawski
2009-12-06 18:53 ` Jarek Poplawski
2009-12-06 18:58 ` Eric Dumazet
2009-12-06 20:18 ` Jarek Poplawski [this message]
2009-12-09 4:46 ` David Miller
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