linux-kernel - Re: [PATCH 2/5] x86/mbm: Intel Memory B/W Monitoring enumeration and init

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Message-ID: <alpine.DEB.2.11.1602241118120.3670@nanos>
Date:	Wed, 24 Feb 2016 11:22:47 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Vikas Shivappa <vikas.shivappa@...ux.intel.com>
cc:	vikas.shivappa@...el.com, x86@...nel.org,
	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	peterz@...radead.org, ravi.v.shankar@...el.com,
	tony.luck@...el.com, fenghua.yu@...el.com,
	kanaka.d.juvva@...el.com, h.peter.anvin@...el.com
Subject: Re: [PATCH 2/5] x86/mbm: Intel Memory B/W Monitoring enumeration
 and init

On Wed, 10 Feb 2016, Vikas Shivappa wrote:ar	
> +static int intel_mbm_init(void)
> +{
> +	int ret = 0, array_size, maxid = cqm_max_rmid + 1;
> +
> +	mbm_socket_max = cpumask_weight(&cqm_cpumask);

This should use the new topology_max_packages() function, so you can alloc
your array correctly even if not all sockets are online/plugged yet.

> +	array_size = sizeof(struct sample) * maxid * mbm_socket_max;
> +	mbm_local = kmalloc(array_size, GFP_KERNEL);
> +	if (!mbm_local) {
> +		ret = -ENOMEM;

return -ENOMEM is sufficient here.

> +		goto out;
> +	}
> +
> +	mbm_total = kmalloc(array_size, GFP_KERNEL);
> +	if (!mbm_total) {
> +		kfree(mbm_local);
> +		ret = -ENOMEM;
> +	}
> +out:
> +
> +	return ret;
> +}
> +
>  	cqm_l3_scale = boot_cpu_data.x86_cache_occ_scale;
> @@ -1384,14 +1520,34 @@ static int __init intel_cqm_init(void)
>  
>  	__perf_cpu_notifier(intel_cqm_cpu_notifier);

You really should register the notifier _AFTER_ registering the pmu. That
needs to be fixed anyway, because the existing code leaks the notifier AND
memory in case perf_pmu_register fails.
  
Thanks,

	tglx