lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 10 May 2016 13:21:10 +0300 From: Roger Quadros <rogerq@...com> To: Felipe Balbi <balbi@...nel.org> CC: <tony@...mide.com>, <Joao.Pinto@...opsys.com>, <sergei.shtylyov@...entembedded.com>, <peter.chen@...escale.com>, <jun.li@...escale.com>, <grygorii.strashko@...com>, <yoshihiro.shimoda.uh@...esas.com>, <nsekhar@...com>, <b-liu@...com>, <linux-usb@...r.kernel.org>, <linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v7 1/5] usb: dwc3: omap: use request_threaded_irq() On 10/05/16 13:12, Felipe Balbi wrote: > > Hi, > > Roger Quadros <rogerq@...com> writes: >>>> @@ -497,8 +503,8 @@ static int dwc3_omap_probe(struct platform_device *pdev) >>>> /* check the DMA Status */ >>>> reg = dwc3_omap_readl(omap->base, USBOTGSS_SYSCONFIG); >>>> >>>> - ret = devm_request_irq(dev, omap->irq, dwc3_omap_interrupt, 0, >>>> - "dwc3-omap", omap); >>>> + ret = devm_request_threaded_irq(dev, omap->irq, dwc3_omap_interrupt, >>>> + NULL, 0, "dwc3-omap", omap); >>> >>> if you're using threaded_irq, it's better to have a NULL top half and >>> valid bottom half. >> >> But in this case we don't need a bottom half as there is nothing to do :). >> >>> >>> In fact, since this will be shared, you could do a proper preparation >>> and on top half check if $this device generated the IRQ and >>> conditionally schedule the bottom half. Don't forget to mask device's >>> interrupts from top half so you can run without IRQF_ONESHOT. >>> >> >> Why do this at all if there is nothing to do in the bottom half? > > oh, but there is :-) > > The whole idea of threaded IRQs is that you spend as little time as > possible on top half and the (strong) recommendation is that you *only* > check if $this device generated the interrupt. Note that "checking if > $this device generated the interrupt" will be mandatory as soon as you > mark the IRQ line as shared ;-) > > So here's how this should look like: > > static irqreturn_t dwc3_omap_interrupt(int irq, void *_omap) > { > struct dwc3_omap *omap = _omap; > u32 reg; > > reg = readl(IRQSTATUS) > if (reg) { > mask_interrupts(omap); > return IRQ_WAKE_THREAD; > } > > return IRQ_HANDLED; > } > > static irqreturn_t dwc3_omap_threaded_interrupt(int irq, void *_omap) > { > struct dwc3_omap *omap = _omap; > u32 reg; > > spin_lock(&omap->lock); > reg = readl(IRQSTATUS); > > if (reg & BIT0) > handle_bit_0(omap); > > if (reg & BIT1) > handle_bit_1(omap); > > unmask_interrupts(omap); > spin_unlock(&omap->lock); > > return IRQ_HANDLED; > } > > this will *always* behave well with RT and non-RT kernels. It also > allows for the user to change priorities on these interrupt handlers if > necessary. > No problem, I can implement a bottom half. We are not handling anything there at the moment so it is a bit of an overkill :) It might help in the future if someone wants to handle something. cheers, -roge
Powered by blists - more mailing lists