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: Wed, 31 Jul 2013 00:16:30 -0700 From: Stephen Boyd <sboyd@...eaurora.org> To: Arpit Goel <B44344@...escale.com> Cc: linux@....linux.org.uk, takata@...ux-m32r.org, philb@....org, geert@...ux-m68k.org, schwidefsky@...ibm.com, heiko.carstens@...ibm.com, linux390@...ibm.com, davem@...emloft.net, rob.herring@...xeda.com, arnd@...db.de, swarren@...dia.com, john.stultz@...aro.org, jesper.nilsson@...s.com, gregkh@...uxfoundation.org, sam@...nborg.org, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, linux-m32r@...linux-m32r.org, linux-m32r-ja@...linux-m32r.org, linux-m68k@...r.kernel.org, linux-s390@...r.kernel.org, sparclinux@...r.kernel.org, mattw@...eaurora.org Subject: Re: [PATCH 2/2] Convert PowerPC macro spin_event_timeout() to architecture independent macro On 07/30, Arpit Goel wrote: > This patch ports PowerPC implementation of spin_event_timeout() for generic > use. Architecture specific implementation can be added to asm/delay.h, which > will override the generic linux implementation. > > Signed-off-by: Arpit Goel <B44344@...escale.com> > --- We use something similar internally but it's tied specifically to readl. > > +#ifndef spin_event_timeout > +/** > + * spin_event_timeout - spin until a condition gets true or a timeout elapses > + * @condition: a C expression to evalate > + * @timeout: timeout, in microseconds > + * @delay: the number of microseconds to delay between each evaluation of > + * @condition > + * > + * The process spins until the condition evaluates to true (non-zero) or the > + * timeout elapses. The return value of this macro is the value of > + * @condition when the loop terminates. This allows you to determine the cause > + * of the loop terminates. If the return value is zero, then you know a > + * timeout has occurred. > + * > + * This primary purpose of this macro is to poll on a hardware register > + * until a status bit changes. The timeout ensures that the loop still > + * terminates even if the bit never changes. The delay is for devices that > + * need a delay in between successive reads. > + * > + * gcc will optimize out the if-statement if @delay is a constant. > + * > + * This is copied from PowerPC based spin_event_timeout() implementation > + * and modified for generic usecase. > + */ > +#define spin_event_timeout(condition, timeout, delay) \ > +({ \ > + typeof(condition) __ret; \ > + unsigned long __loops = timeout/USECS_PER_JIFFY; \ > + unsigned long __start = jiffies; \ > + while (!(__ret = (condition)) && \ > + time_before(jiffies, __start + __loops + 1)) \ > + if (delay) \ > + udelay(delay); \ > + else \ > + schedule(); \ > + if (!__ret) \ > + __ret = (condition); \ > + __ret; \ > +}) What do you do here if jiffies aren't incrementing (i.e interrupts are disabled). The time_before() check won't work there and it would be nice if we were able to use this in such situations. I think powerpc gets around this by reading the hardware timer directly? -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists