On Wed, 2006-11-15 at 02:08, Eric W. Biederman wrote: > Ingo Molnar <mingo@xxxxxxx> writes: > > > * Andrew Morton <akpm@xxxxxxxx> wrote: > > > >> On Tue, 14 Nov 2006 17:08:10 +0800 > >> "Zhang, Yanmin" <yanmin_zhang@xxxxxxxxxxxxxxx> wrote: > >> > >> > I got an oops when booting 2.6.19-rc5-mm1 on my ia64 machine. > >> > > >> > > >> > The root cause is that some irq_chip variables, especially ia64_msi_chip, > >> > initiate their memeber end to point to NULL. __do_IRQ doesn't check > >> > if irq_chip->end is null and just calls it after processing the interrupt. > >> > > >> > As irq_chip->end is called at many places, so I fix it by reinitiating > >> > irq_chip->end to dummy_irq_chip.end, e.g., a noop function. > >> > > >> > Below patch against 2.6.19-rc5-mm1 fixes it. > >> > > >> > Signed-off-by: Zhang Yanmin <yanmin.zhang@xxxxxxxxx> > >> > > >> > --- > >> > > >> > --- linux-2.6.19-rc5-mm1/kernel/irq/chip.c 2006-11-14 14:16:16.000000000 > > +0800 > >> > +++ linux-2.6.19-rc5-mm1_fix/kernel/irq/chip.c 2006-11-14 14:14:25.000000000 > > +0800 > >> > @@ -233,6 +233,8 @@ void irq_chip_set_defaults(struct irq_ch > >> > chip->shutdown = chip->disable; > >> > if (!chip->name) > >> > chip->name = chip->typename; > >> > + if (!chip->end) > >> > + chip->end = dummy_irq_chip.end; > >> > } > >> > > >> > >> The same bug should be hitting in mainline, shouldn't it? > > > > correct. > > > > this bug comes from a 'mixed' IRQ setup on ia64: half of it is still > > old-style, half of it (the MSI stuff) is new-style irqchip code. But the > > ia64 lowlevel code unconditionally calls __do_IRQ(), which is a bug. > > Now that we hare half converted yes it is a bug. > > > the genirq code has all the right helpers for such a mixed situation: so > > a better fix might be the one below: use generic_handle_irq() instead of > > unconditionally calling into __do_IRQ(). But i have not tested it - > > Yanmin, can you confirm this too fixes your bug? > > > > similarly, any architecture that makes use of the new generic MSI > > infrastructure should not be calling __do_IRQ() directly. (but i'm not > > aware of any other besides ia64 - i386 and x86_64 is now fully irq-chip > > converted.) > > > > Eric, do you agree? > > > > This is true in practice. It isn't necessarily true, as all of irq_chip > structures are arch specific. It would be silly to start using msi interrupts > without converting to genirq though. So I think this covers it for ia64. > > Your patch only fixes 2 spots and there is a third in irq_ia64.c that > needs to be fixed as well. At least in linus's tree. Based on Eric's comments, I added a new change into Ingo's patch, and tested on my ia64 machine. It does fix the bug and works well. I still think my original patch to initilate null end to dummy_irq_chip.end is useful, at least to prevent potential errors. --- --- linux-2.6.19-rc5-mm1/arch/ia64/kernel/irq.c 2006-11-14 14:16:12.000000000 +0800 +++ linux-2.6.19-rc5-mm1_fix/arch/ia64/kernel/irq.c 2006-11-15 09:56:01.000000000 +0800 @@ -197,7 +197,7 @@ void fixup_irqs(void) struct pt_regs *old_regs = set_irq_regs(NULL); vectors_in_migration[irq]=0; - __do_IRQ(irq); + generic_handle_irq(irq); set_irq_regs(old_regs); } } --- linux-2.6.19-rc5-mm1/arch/ia64/kernel/irq_ia64.c 2006-11-14 14:16:12.000000000 +0800 +++ linux-2.6.19-rc5-mm1_fix/arch/ia64/kernel/irq_ia64.c 2006-11-15 09:56:51.000000000 +0800 @@ -186,7 +186,7 @@ ia64_handle_irq (ia64_vector vector, str ia64_setreg(_IA64_REG_CR_TPR, vector); ia64_srlz_d(); - __do_IRQ(local_vector_to_irq(vector)); + generic_handle_irq(local_vector_to_irq(vector)); /* * Disable interrupts and send EOI: @@ -242,7 +242,7 @@ void ia64_process_pending_intr(void) * Probably could shared code. */ vectors_in_migration[local_vector_to_irq(vector)]=0; - __do_IRQ(local_vector_to_irq(vector)); + generic_handle_irq(local_vector_to_irq(vector)); set_irq_regs(old_regs); /* - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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