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Subject: Re: [PATCH 1/2] powerpc/ps3: Fix lost SMP IPIs
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Geoff Levand <geoff@infradead.org>
Date: Wed, 09 Nov 2011 10:53:36 +0100
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Cc: cbe-oss-dev@lists.ozlabs.org, Andre Heider <a.heider@gmail.com>,
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On Tue, 2011-11-08 at 14:37 -0800, Geoff Levand wrote:
> Fixes the PS3 bootup hang introduced in 3.0-rc1 by:
>=20
>   commit 317f394160e9beb97d19a84c39b7e5eb3d7815a
>   sched: Move the second half of ttwu() to the remote cpu
>=20
> Move the PS3's LV1 EOI call lv1_end_of_interrupt_ext() from ps3_chip_eoi(=
)
> to ps3_get_irq() for IPI messages.
>=20
> If lv1_send_event_locally() is called between a previous call to
> lv1_send_event_locally() and the coresponding call to
> lv1_end_of_interrupt_ext() the second event will not be delivered to the
> target cpu.
>=20
> The PS3's SMP IPIs are implemented using lv1_send_event_locally(), so if =
two
> IPI messages of the same type are sent to the same target in a relatively
> short period of time the second IPI event can become lost when
> lv1_end_of_interrupt_ext() is called from ps3_chip_eoi().=20

Ah glad you found it! I'm not going to ack it since PPC guts are way
beyond me.