Re: [PATCH v6 net-next 2/5] net: implement support for low latency socket polling

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

On Wed, 2013-05-29 at 09:39 +0300, Eliezer Tamir wrote:

> +/* we don't mind a ~2.5% imprecision */
> +#define TSC_MHZ (tsc_khz >> 10)
> +
> +static inline unsigned long ll_end_time(void)
> +{
> +	return TSC_MHZ * ACCESS_ONCE(sysctl_net_ll_poll) + get_cycles();
> +}static inline unsigned long ll_end_time(void)
>+{
>+	return TSC_MHZ * ACCESS_ONCE(sysctl_net_ll_poll) + get_cycles();
>+}

This can overflow.

Multiply is giving 32bits, as tsc_khz is an int, and sysctl_net_ll_poll
is an int.

unsigned long sysctl_net_ll_poll ?

Also, if we want this to work on i386, the correct type to use for
ll_end_time(void) would be cycles_t




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