Re: [PATCH v6 19/22] x86/resctrl: Introduce the interface to switch between monitor modes

[Reinette Chatre]

Hi Babu,

On 8/6/24 3:00 PM, Babu Moger wrote:
> +static ssize_t rdtgroup_mbm_mode_write(struct kernfs_open_file *of,
> +				       char *buf, size_t nbytes,
> +				       loff_t off)
> +{
> +	int mbm_cntr_assign = resctrl_arch_get_abmc_enabled();

This needs to be protected by the mutex.

> +	struct rdt_resource *r = of->kn->parent->priv;
> +	int ret = 0;
> +
> +	/* Valid input requires a trailing newline */
> +	if (nbytes == 0 || buf[nbytes - 1] != '\n')
> +		return -EINVAL;
> +
> +	buf[nbytes - 1] = '\0';
> +
> +	cpus_read_lock();
> +	mutex_lock(&rdtgroup_mutex);
> +
> +	rdt_last_cmd_clear();
> +
> +	if (!strcmp(buf, "legacy")) {
> +		if (mbm_cntr_assign)
> +			resctrl_arch_mbm_cntr_assign_disable();
> +	} else if (!strcmp(buf, "mbm_cntr_assign")) {
> +		if (!mbm_cntr_assign) {
> +			rdtgroup_mbm_cntr_reset(r);
> +			ret = resctrl_arch_mbm_cntr_assign_enable();
> +		}
> +	} else {
> +		ret = -EINVAL;
> +	}
> +
> +	mutex_unlock(&rdtgroup_mutex);
> +	cpus_read_unlock();
> +
> +	return ret ?: nbytes;
> +}
> +

Reinette