Re: [PATCH v3 22/25] irq_domain/x86: Convert x86 (embedded) to use common irq_domain

On Sat, Jan 28, 2012 at 5:35 PM, Grant Likely [off-list ref] w=
rote:

On Sat, Jan 28, 2012 at 05:44:05PM +0100, Sebastian Andrzej Siewior wrote=

:

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* Grant Likely | 2012-01-27 14:36:16 [-0700]:

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This patch removes the x86-specific definition of irq_domain and replac=

es

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it with the common implementation.

I pulled your devicetree/next tree. After this patch I get:

|Hierarchical RCU implementation.
|NR_IRQS:2304 nr_irqs:256 16
|------------[ cut here ]------------
|WARNING: at /home/bigeasy/work/shiva/git/linux-2.6-tip/kernel/irq/irqdo=

main.c:114 irq_domain_add_legacy+0x75/0x150()

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|Modules linked in:
|Pid: 0, comm: swapper/0 Not tainted 3.3.0-rc1+ #65
|Call Trace:
| [<c15044e0>] ? printk+0x18/0x1a
| [<c102cdbd>] warn_slowpath_common+0x6d/0xa0
| [<c1095575>] ? irq_domain_add_legacy+0x75/0x150
| [<c1095575>] ? irq_domain_add_legacy+0x75/0x150
| [<c102ce0d>] warn_slowpath_null+0x1d/0x20
| [<c1095575>] irq_domain_add_legacy+0x75/0x150
| [<c1714824>] x86_add_irq_domains+0x96/0xd6
| [<c1708df2>] init_IRQ+0x8/0x33
| [<c170557f>] start_kernel+0x191/0x2e1
| [<c170517f>] ? loglevel+0x2b/0x2b
| [<c1705081>] i386_start_kernel+0x81/0x86
|---[ end trace 4eaa2a86a8e2da22 ]---
|------------[ cut here ]------------
|kernel BUG at /home/bigeasy/work/shiva/git/linux-2.6-tip/arch/x86/kerne=

l/devicetree.c:367!

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The warning is comming from this piece in irq_domain_add_legacy()
|for (i =3D 0; i < size; i++) {
| =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 int irq =3D first_irq + i;
| =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct irq_data *irq_data =3D irq_get_=

irq_data(irq);

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|
| =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (WARN_ON(!irq_data || irq_data->dom=

ain)) {

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irq_data is NULL here.

| =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 mutex_unlock(&irq_doma=

in_mutex);

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| =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 of_node_put(domain->of=

_node);

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| =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 kfree(domain);
| =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return NULL;
| =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
| =A0 =A0 =A0 =A0 }
|

This is not always the case. arch_early_irq_init() in [0] sets up the
first 16 entries. The reminaing few (there is a toal of 24 irqs for
first ioapic and a second ioapic) are not initialized. This happens
later via ->xlate, ioapic_xlate() =3D> io_apic_setup_irq_pin() =3D>
alloc_irq_and_cfg_at() calls irq_set_chip_data() on demand.

[0] arch/x86/kernel/apic/io_apic.c

That's not going to work then. =A0The irqs must not be set up in ->xlate.
They need to be set up either before creating the irq_domain, or in the
.map hook. =A0Inside the map hook is preferred, but having some
configured and some not at initialization time does make it difficult

Actually, that's still not right.  irq_set_chip_data() (sets
desc->irq_data.chip_data) has nothing to do with irq_get_irq_data()
(which returns desc->irq_data).  It's the   allocation of the irq_desc
that is at issue here.  Where does the allocation occur?  (I haven't
dug in to find it yet)

g.