Re: [PATCH v2] dma: Add Xilinx AXI Video Direct Memory AccessEngine driver support

From: Shevchenko, Andriy
Date: Thu Jan 23 2014 - 08:38:50 EST

On Thu, 2014-01-23 at 12:25 +0100, Lars-Peter Clausen wrote:
> On 01/22/2014 05:52 PM, Srikanth Thokala wrote:


> > + /* Request the interrupt */
> > + chan->irq = irq_of_parse_and_map(node, 0);
> > + err = devm_request_irq(xdev->dev, chan->irq, xilinx_vdma_irq_handler,
> > + IRQF_SHARED, "xilinx-vdma-controller", chan);
> This is a clasic example of where to not use devm_request_irq. 'chan' is
> accessed in the interrupt handler, but if you use devm_request_irq 'chan'
> will be freed before the interrupt handler has been released, which means
> there is now a race condition where the interrupt handler can access already
> freed memory.

Could you elaborate this case? As far as I understood managed resources
are a kind of stack pile. In this case you have no such condition. Where
am I wrong?

Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
Intel Finland Oy
Intel Finland Oy
Registered Address: PL 281, 00181 Helsinki
Business Identity Code: 0357606 - 4
Domiciled in Helsinki

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