Messages in this thread | | | Date | Mon, 24 May 2004 00:33:08 +0100 | From | Russell King <> | Subject | Re: scheduler: IRQs disabled over context switches |
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On Sun, May 23, 2004 at 04:04:39PM -0700, Davide Libenzi wrote: > On Sun, 23 May 2004, Russell King wrote: > > Not quite - look harder. They use spin_unlock_irq in finish_arch_switch > > rather than prepare_arch_switch. > > Hmm, they do indeed. Hmm, if we release the rq lock before the ctx switch, > "prev" (the real one) will result not running since we already set > "rq->curr" to "next" (and we do not hold "prev->switch_lock").
We do hold prev->switch_lock - we hold it all the time that the thread is running. Consider what prepare_arch_switch() is doing - it's taking the next threads switch_lock. It only gets released _after_ we've switched away from that thread.
So I think your analysis is flawed.
-- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/ 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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