linux-kernel - Re: [PATCH 3/4] nvme: pci: pass IRQF_RESCURE_THREAD to request_threaded

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Date:   Tue, 27 Aug 2019 08:34:21 -0600
From:   Keith Busch <kbusch@...nel.org>
To:     Ming Lei <ming.lei@...hat.com>
Cc:     Johannes Thumshirn <jthumshirn@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Long Li <longli@...rosoft.com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Keith Busch <keith.busch@...el.com>, Jens Axboe <axboe@...com>,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        John Garry <john.garry@...wei.com>,
        Hannes Reinecke <hare@...e.com>,
        linux-nvme@...ts.infradead.org, linux-scsi@...r.kernel.org
Subject: Re: [PATCH 3/4] nvme: pci: pass IRQF_RESCURE_THREAD to
 request_threaded_irq

On Tue, Aug 27, 2019 at 05:09:27PM +0800, Ming Lei wrote:
> On Tue, Aug 27, 2019 at 11:06:20AM +0200, Johannes Thumshirn wrote:
> > On 27/08/2019 10:53, Ming Lei wrote:
> > [...]
> > > +		char *devname;
> > > +		const struct cpumask *mask;
> > > +		unsigned long irqflags = IRQF_SHARED;
> > > +		int vector = pci_irq_vector(pdev, nvmeq->cq_vector);
> > > +
> > > +		devname = kasprintf(GFP_KERNEL, "nvme%dq%d", nr, nvmeq->qid);
> > > +		if (!devname)
> > > +			return -ENOMEM;
> > > +
> > > +		mask = pci_irq_get_affinity(pdev, nvmeq->cq_vector);
> > > +		if (mask && cpumask_weight(mask) > 1)
> > > +			irqflags |= IRQF_RESCUE_THREAD;
> > > +
> > > +		return request_threaded_irq(vector, nvme_irq, NULL, irqflags,
> > > +				devname, nvmeq);
> > 
> > This will leak 'devname' which gets allocated by kasprintf() a few lines
> > above.
> 
> It won't, please see pci_free_irq() in which free_irq() returns the
> 'devname' passed in.

Only if request_threaded_irq() doesn't return an error.

I think you should probably just have pci_irq_get_affinity() take a flags
argument, or make a new function like __pci_irq_get_affinity() that
pci_irq_get_affinity() can call with a default flag.