From: Philippe Gerum <rpm@xenomai.org>
To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: xenomai-core <xenomai@xenomai.org>
Subject: Re: [Xenomai-core] BUG on xnintr_attach
Date: Wed, 22 Apr 2009 18:23:04 +0200 [thread overview]
Message-ID: <1240417384.6987.8.camel@domain.hid> (raw)
In-Reply-To: <49EF0CFE.90405@domain.hid>
On Wed, 2009-04-22 at 14:26 +0200, Jan Kiszka wrote:
> Hi all,
>
> issuing rtdm_irq_request and, thus, xnintr_attach can trigger a
> "I-pipe: Detected stalled topmost domain, probably caused by a bug." if
> the interrupt type is MSI:
>
> [<ffffffff80273cce>] ipipe_check_context+0xe7/0xe9
> [<ffffffff8049dae9>] _spin_lock_irqsave+0x18/0x54
> [<ffffffff8037dcc2>] pci_bus_read_config_dword+0x3c/0x87
> [<ffffffff80387c1d>] read_msi_msg+0x61/0xe1
> [<ffffffff8021c5b8>] ? assign_irq_vector+0x3e/0x49
> [<ffffffff8021d7b2>] set_msi_irq_affinity+0x6d/0xc8
> [<ffffffff8021fa5d>] __ipipe_set_irq_affinity+0x6c/0x77
> [<ffffffff80274231>] ipipe_set_irq_affinity+0x34/0x3d
> [<ffffffff8027c572>] xnintr_attach+0xaa/0x11e
>
> Two option to fix this, but I'm currently undecided which one to go:
> - harden pci_lock (drivers/pci/access.c) - didn't we applied such a
> MSI-related workaround before?
This did not work as expected: pathological latency spots. This said,
the vanilla code has evolved since I tried this quick hack months ago,
so it may be worth to look at this option once again.
> - move xnarch_set_irq_affinity out of intrlock (but couldn't we face
> even more pci_lock related issues?)
>
Since upstream decided to use PCI config reads even inside hot paths
when processing MSI interrupts, the only sane way would be to make the
locking used there Adeos-aware, likely virtualizing the interrupt mask.
The way upstream generally deals with MSI is currently a problem for us.
> Jan
>
--
Philippe.
next prev parent reply other threads:[~2009-04-22 16:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-22 12:26 [Xenomai-core] BUG on xnintr_attach Jan Kiszka
2009-04-22 16:23 ` Philippe Gerum [this message]
2009-04-22 16:48 ` Jan Kiszka
2009-04-23 7:20 ` Jan Kiszka
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