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Date: Fri, 1 Jul 2011 17:49:52 +0800
Message-ID: <BANLkTimGAuyMP43eDUet7Ts0XU9WQRYbyQ@mail.gmail.com>
Subject: tick_setup_device in tick-common.c
From: chao xie <xiechao.linux@gmail.com>
To: linux-kernel@vger.kernel.org
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hi
I am very strange about this function.
In this function, it has
/*
         * When the device is not per cpu, pin the interrupt to the
         * current cpu:
         */
        if (!cpumask_equal(newdev->cpumask, cpumask))
                irq_set_affinity(newdev->irq, cpumask);

When the clock event device has cpu_mask set to be cpumask_of(1), it
means that the device is bound to cpu1. So above code has covered it,
but why we have "!cpumask_equal(newdev->cpumask, cpumask)"?
if the "newdev->cpumask" equals "cpumask", cpumask_equal will return
1, and at this situation we will set the irq affinity because the
device is bound to the dedicated cpu.

Is there a bug, or i understand wrong about cpumask of clock_event_device?
Thanks.