Anders Blomdell wrote:
Philippe Gerum wrote:
Anders Blomdell wrote:
On a PrPMC800 (PPC 7410 processor) withe Xenomai-2.1-rc2, I get the
following if the interrupt handler takes too long (i.e. next
interrupt gets generated before the previous one has finished)
[ 42.543765] [c00c2008] spin_bug+0xa8/0xc4
[ 42.597617] [c00c22d4] _raw_spin_lock+0x180/0x184
Someone (in arch/ppc64/kernel/*.c?) is spinlocking+irqsave desc->lock
more likely arch/ppc/kernel/*.c :-)
Gah... looks like I'm still confused by ia64 issues I'm chasing right now. (Why on
earth do we need so many bits on our CPUs that only serve the purpose of raising
so many problems?)
for any given IRQ without using the Adeos *_hw() spinlock variant that
masks the interrupt at hw level. So we seem to have:
spin_lock_irqsave(&desc->lock)
<hw IRQ>
__ipipe_grab_irq
__ipipe_handle_irq
__ipipe_ack_irq
spin_lock...(&desc->lock)
deadlock.
The point is about having spinlock_irqsave only _virtually_ masking
the interrupts by preventing their associated Linux handler from being
called, but despite this, Adeos still actually acquires and
acknowledges the incoming hw events before logging them, even if their
associated action happen to be postponed until spinlock_irq_restore()
is called.
To solve this, all spinlocks potentially touched by the ipipe's
primary IRQ handler and/or the code it calls indirectly, _must_ be
operated using the _hw() call variant all over the kernel, so that no
hw IRQ can be taken while those spinlocks are held by Linux. Usually,
only the spinlock(s) protecting the interrupt descriptors or the PIC
hardware are concerned.
So you will expect an addition to the ipipe patch then?
Yep. We first need to find out who's grabbing the shared spinlock using the
vanilla Linux primitives.
/Anders
--
Philippe.
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