Hi Russell, On Fri, Jul 25, 2014 at 05:45:19PM +0100, Russell King - ARM Linux wrote: > On Fri, Jul 25, 2014 at 06:37:46PM +0200, Maxime Ripard wrote: > > Hi Vinod, > > > > On Fri, Jul 25, 2014 at 06:42:17PM +0530, Vinod Koul wrote: > > > - don't use devm_request_irq(). You have irq enabled and you have killed > > > tasklet. This is too racy. You need to ensure no irqs can be generated before killing > > > tasklets. > > > > Ok, would calling disable_irq before killing the tasklet an option for > > you ? that would allow to keep the devm_request_irq. > > That's not really an acceptable approach if you can use shared > interrupts. We don't, but yes, I see your point. > A better alternative would be devm_free_irq() to give a definite point > that the interrupt is unregistered in the driver remove sequence. That > allows you to keep the advantage of devm_request_irq() to clean up during > the initialisation side. Ah, right, thanks. > An alternative approach would be to ensure that the hardware is quiesced, > and interrupts are disabled. Then call synchronize_irq() on it, and at > that point, you should be certain that your interrupt handler should not > process any further interrupts for your device (though, in a shared > interrupt environment, it would still be called should a different device > on the shared line raise its interrupt.) Actually, unless I'm missing something, that's pretty much what we're doing here. I disable all interrupts in the DMA controller, I call synchronize_irq, and then kill the tasklet. The only interrupts I could get are spurious, and we made sure such kind of interrupts couldn't schedule the tasklet either. Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com
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