linux-kernel - Re: [Bugfix v2 3/5] x86/irq: Fix a race window in x86_vector_free

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Date:	Tue, 29 Dec 2015 14:39:46 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Jiang Liu <jiang.liu@...ux.intel.com>
cc:	Joe Lawrence <joe.lawrence@...atus.com>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Jeremiah Mahler <jmmahler@...il.com>,
	Borislav Petkov <bp@...en8.de>, andy.shevchenko@...il.com,
	Guenter Roeck <linux@...ck-us.net>,
	linux-kernel@...r.kernel.org
Subject: Re: [Bugfix v2 3/5] x86/irq: Fix a race window in
 x86_vector_free_irqs()

On Wed, 23 Dec 2015, Jiang Liu wrote:
>  void init_irq_alloc_info(struct irq_alloc_info *info,
> @@ -279,18 +272,21 @@ static void x86_vector_free_irqs(struct irq_domain *domain,
>  				 unsigned int virq, unsigned int nr_irqs)
>  {
>  	struct irq_data *irq_data;
> +	unsigned long flags;
>  	int i;
>  
>  	for (i = 0; i < nr_irqs; i++) {
>  		irq_data = irq_domain_get_irq_data(x86_vector_domain, virq + i);
>  		if (irq_data && irq_data->chip_data) {
> +			raw_spin_lock_irqsave(&vector_lock, flags);
>  			clear_irq_vector(virq + i, irq_data->chip_data);
>  			free_apic_chip_data(irq_data->chip_data);
> +			irq_domain_reset_irq_data(irq_data);
> +			raw_spin_unlock_irqrestore(&vector_lock, flags);

We really do not need to free stuff under the vector lock.

   lock();
   data = irq_data->chip_data;
   irq_domain_reset_irq_data(irq_data);
   unlock();
   free_apic_chip_data(data);

Hmm?	

Thanks,

	tglx
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