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Date: Fri, 7 Mar 2014 14:14:23 +0200 From: Ville Syrjälä <ville.syrjala@...ux.intel.com> To: Thomas Gleixner <tglx@...utronix.de> Cc: linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...nel.org Subject: Re: preempt_check_resched() gone? On Thu, Mar 06, 2014 at 09:52:42PM +0100, Thomas Gleixner wrote: > On Thu, 6 Mar 2014, Ville Syrjälä wrote: > > Hi, > > > > It appears preempt_check_resched() is no longer available for modules > > since [1]. So now I'm left wondering what is one supposed to use after > > local_irq_enable(). Documentation/preempt-locking.txt still says one > > should do a check, but the tool to do that was taken away. > > The documentation is slightly misleading. The point is: > > If you have an irq disabled section and you do a wakeup inside this > section which causes the need resched bit to be set, then > local_irq_enable/restore wont do an preemption check. > > If you merily poke at a few device registers then nothing will set > need resched and you're good. OK. There are a few extra things that get called while irqs are disabled: prepare_to_wait(), finish_wait(), mod_timer(), spin_{lock,unlock}(). Based on a quick glance none of those should do anything I need to worry about, so I'll just drop preempt_check_resched() from my code. Thanks. -- Ville Syrjälä Intel OTC -- 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/
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