linux-kernel - Re: [PULL 2/2] vhost: replace rcu with mutex

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Message-ID: <538DC422.1050303@redhat.com>
Date:	Tue, 03 Jun 2014 14:48:34 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	"Michael S. Tsirkin" <mst@...hat.com>
CC:	netdev@...r.kernel.org, virtualization@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	David Miller <davem@...emloft.net>
Subject: Re: [PULL 2/2] vhost: replace rcu with mutex

Il 02/06/2014 23:58, Eric Dumazet ha scritto:
> This looks dubious
>
> What about using kfree_rcu() instead ?

It would lead to unbound allocation from userspace.

> translate_desc() still uses rcu_read_lock(), its not clear if the mutex
> is really held.

Yes, vhost_get_vq_desc must be called with the vq mutex held.

The rcu_read_lock/unlock in translate_desc is unnecessary.

Paolo
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