Messages in this thread | | | From | "TK, Pratheesh Gangadhar" <> | Date | Mon, 28 Feb 2011 09:32:54 +0530 | Subject | RE: [PATCH v5 1/2] PRUSS UIO driver support |
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Hi,
> -----Original Message----- > From: Thomas Gleixner [mailto:tglx@linutronix.de] > Sent: Friday, February 25, 2011 3:24 PM > To: TK, Pratheesh Gangadhar > Cc: davinci-linux-open-source@linux.davincidsp.com; hjk@hansjkoch.de; > gregkh@suse.de; sshtylyov@mvista.com; arnd@arndb.de; Chatterjee, Amit; > linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org > Subject: Re: [PATCH v5 1/2] PRUSS UIO driver support > > On Fri, 25 Feb 2011, Pratheesh Gangadhar wrote: > > +static irqreturn_t pruss_handler(int irq, struct uio_info *dev_info) > > +{ > > + void __iomem *base = dev_info->mem[0].internal_addr; > > + void __iomem *intren_reg = base + PINTC_HIER; > > + void __iomem *intrstat_reg = base + PINTC_HIPIR + ((irq - 1) << 2); > > + int val = ioread32(intren_reg), intr_mask = (1 << (irq - 1)); > > + > > + /* Is interrupt enabled and active ? */ > > + if (!(val & intr_mask) && (ioread32(intrstat_reg) & HIPIR_NOPEND)) > > + return IRQ_NONE; > > + > > + /* Disable interrupt */ > > + iowrite32((val & ~intr_mask), intren_reg); > > + return IRQ_HANDLED; > > +} > > Hmm, just noticed, that you fiddle with the interrupt enable register > here totally unprotected. So on a SMP system you might haandle two > different interrupts at the same time. That wants locking. > > And even on UP, you have a problem as you reenable that thing from > user space which requires a read modify write. Racy as hell. > > Please look at the other UIO drivers which have the same problem. > Sorry for not noticing earlier!
Thanks for pointing this out. Yes - this is a problem especially since we have more than one interrupt for PRUSS which is enabled/disabled in this register. I will fix this and resubmit along with fixes addressing Sergei's comments on platform specific portion.
Thanks, Pratheesh
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