spin_lock_irqsave and multi-core

[Benjamin Herrenschmidt]

On Thu, 2010-04-01 at 10:41 +0800, gshan wrote:

> One of my private driver need it. I don't know how to do it.

Then your driver is most certainly doing something wrong :-) No driver
needs that. Ever.

What is it trying to do more precisely ? I might be able to explain what
the right approach is if you can tell me what the driver is trying to
disable all system IRQs for ? Keep in mind that local_irq_save() does a
lot more than just masking external interrupts from your device. It
masks them from -all- devices, including timer interrupts, perfmon
interrupts, etc... Doing so on all cores is generally a big no-no and
almost never really necessary.

Cheers,
Ben.