Philippe Gerum wrote: > 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.
Hmm, guess this needs a closer look again. But I vaguely recall upstream had removed the config reading at least from the hot paths due to complaints about performance. However, I think we go with approach 1 independently. So please pull this from git://git.xenomai.org/xenomai-jki.git for-upstream Jan ---------> Subject: [PATCH] nucleus: Move xnarch_set_irq_affinity out of intrlock There is no need to hold intrlock while setting the affinity of the to-be-registered IRQ. Additionally, we have troubles with MSI code that can use Linux locks from within this service. So move the affinity adjustment out of the critical section. Signed-off-by: Jan Kiszka <jan.kis...@siemens.com> --- ksrc/nucleus/intr.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/ksrc/nucleus/intr.c b/ksrc/nucleus/intr.c index 870efb1..dba3b26 100644 --- a/ksrc/nucleus/intr.c +++ b/ksrc/nucleus/intr.c @@ -721,11 +721,12 @@ int xnintr_attach(xnintr_t *intr, void *cookie) intr->cookie = cookie; memset(&intr->stat, 0, sizeof(intr->stat)); - xnlock_get_irqsave(&intrlock, s); - #ifdef CONFIG_SMP xnarch_set_irq_affinity(intr->irq, nkaffinity); #endif /* CONFIG_SMP */ + + xnlock_get_irqsave(&intrlock, s); + err = xnintr_irq_attach(intr); if (!err) _______________________________________________ Xenomai-core mailing list Xenomaifirstname.lastname@example.org https://mail.gna.org/listinfo/xenomai-core