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Date: Fri, 12 May 2017 10:40:53 +0200 (CEST) From: Thomas Gleixner <tglx@...utronix.de> To: Gregory Fong <gregory.0xf0@...il.com> cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, linux@...linux.org.uk, Florian Fainelli <f.fainelli@...il.com> Subject: Re: handle_bad_irq and locking On Thu, 11 May 2017, Gregory Fong wrote: > Hi Thomas, > > I noticed that when you changed arm irq handling to use the generic > implementation back in 2006 that you changed do_bad_IRQ() to the > following: > > +#define do_bad_IRQ(irq,desc,regs) \ > +do { \ > + spin_lock(&desc->lock); \ > + handle_bad_irq(irq, desc, regs); \ > + spin_unlock(&desc->lock); \ > +} while(0) > > and it's mostly stayed the same since then. As such, there are a few > examples of this being open-coded in the kernel in various irqchip > handlers such as that of drivers/irqchip/irq-brcmstb-l2.c, and even > more cases where the lock isn't being grabbed before calling > handle_bad_irq(). > > Since handle_bad_irq() is sort of a flow handler like > handle_edge_irq() etc., do you think it would make sense to do the > same as those and have it do the locking on its own? A quick look > through existing users of handle_bad_irq() at [1] suggests that either > the locking isn't necessary or it's almost always done wrong. Right. So the proper solution to this is to create a generic function handle_bad_irq_desc() have proper locking in it and move all users (including do_bad_IRQ()) over to it. Thanks, tglx
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