Re: [RFC] netem: correlated loss generation (v3)

[Eric Dumazet <eric.dumazet@gmail.com>]

Le lundi 17 mai 2010 à 20:56 -0700, Stephen Hemminger a écrit :
> Subject: netem - revised correlated loss generator
> 
> This is a patch originated with Stefano Salsano and Fabio Ludovici.
> It provides several alternative loss models for use with netem.
> There are two state machine based models and one table driven model.
> 
> To simplify the original code:
>    * eliminated the debugging messages and statistics
>    * reformatted for clarity
>    * changed API to nested attribute relating to loss
>    * changed the table to always loop across bits
>    * only allocate parameters needed
> 
> Still untested, for comment only...
> Should have tested version before 2.6.35 merge window closes.
> 
> Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>


> +	if (loss[NETEM_LOSS_SEQUENCE]) {
> +		struct dlgtable *dlg;
> +		size_t len = nla_len(loss[NETEM_LOSS_SEQUENCE]);
> +
> +		dlg = kmalloc(sizeof(*dlg) + len, GFP_KERNEL);

No overflow check here, len comes from userland.

> +		if (dlg)
> +			goto nomem;
> +
> +		dlg->length = len * BITS_PER_LONG;
> +		dlg->index = 0;
> +		memcpy(dlg->sequence, nla_data(loss[NETEM_LOSS_SEQUENCE]), len);
> +
> +		kfree(q->dlg);
> +		q->dlg = dlg;
> +	}
> +
> +	q->loss_model = model;
> +	sch_tree_unlock(sch);