Re: [PATCH 3/3] vhost-net: use lock_sock_fast() in peek_head_len()

Le dimanche 13 mars 2011 à 18:43 +0200, Michael S. Tsirkin a écrit :

On Sun, Mar 13, 2011 at 05:32:07PM +0100, Eric Dumazet wrote:

quoted

Le dimanche 13 mars 2011 à 18:19 +0200, Michael S. Tsirkin a écrit :

quoted

Other side is in drivers/net/tun.c and net/packet/af_packet.c
At least wrt tun it seems clear socket is not locked.

Yes (assuming you refer to tun_net_xmit())

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Besides queue, dequeue seems to be done without socket locked.

It seems this code (assuming you speak of drivers/vhost/net.c ?) has
some races indeed.

Hmm. Any more besides the one fixed here?

If writers and readers dont share a common lock, how can they reliably
synchronize states ?

For example, the check at line 420 seems unsafe or useless.

skb_queue_empty(&sock->sk->sk_receive_queue)