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 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.
[ 42.660637] [c000f388] __ipipe_ack_irq+0x88/0x130
[ 42.723657] [c000efe4] __ipipe_handle_irq+0x140/0x268
[ 42.791259] [c000f144] __ipipe_grab_irq+0x38/0xa4
[ 42.854279] [c0005058] __ipipe_ret_from_except+0x0/0xc
[ 42.923029] [00000000] 0x0
[ 42.959695] [c0038348] __do_IRQ+0x134/0x164
[ 43.015839] [c000ed04] __ipipe_do_IRQ+0x2c/0x44
[ 43.076567] [c000eb08] __ipipe_sync_stage+0x1ec/0x228
[ 43.144170] [c0039420] ipipe_suspend_domain+0x7c/0xc4
[ 43.211774] [c000f0b0] __ipipe_handle_irq+0x20c/0x268
[ 43.279377] [c000f144] __ipipe_grab_irq+0x38/0xa4
[ 43.342396] [c0005058] __ipipe_ret_from_except+0x0/0xc
[ 43.411145] [c0006524] default_idle+0x10/0x60
Any ideas of where to look?
Regards
Anders Blomdell
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Philippe.
