Messages in this thread | | | Date | Thu, 1 Apr 2010 13:12:36 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: start_kernel(): bug: interrupts were enabled early |
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On Thu, 1 Apr 2010, Andrew Morton wrote: > > > So making the slow-path do the spin_[un]lock_irq{save,restore}() versions > > sounds like the right thing. It won't be a performance issue: it _is_ the > > slow-path, and we're already doing the expensive part (the spinlock itself > > and the irq thing). > > It's actually on the fastpath for lib/rwsem-spinlock.c.
Ahh, yes. In this case, that doesn't likely change anything. The save/restore versions of the irq-safe locks shouldn't be appreciably more expensive than the non-saving ones. And architectures that really care should have done their own per-arch optimized version anyway.
Maybe we should even document that - so that nobody else makes the mistake x86-64 did of thinking that the "generic spinlock" version of the rwsem's is anything but a hacky and bad fallback case.
Linus
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