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

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Message-ID: <20120129003550.GA21385@ponder.secretlab.ca>
Date:	Sat, 28 Jan 2012 17:35:50 -0700
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:	linux-kernel@...r.kernel.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Milton Miller <miltonm@....com>,
	Rob Herring <rob.herring@...xeda.com>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	devicetree-discuss@...ts.ozlabs.org,
	linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v3 22/25] irq_domain/x86: Convert x86 (embedded) to use
 common irq_domain

On Sat, Jan 28, 2012 at 05:44:05PM +0100, Sebastian Andrzej Siewior wrote:
> * Grant Likely | 2012-01-27 14:36:16 [-0700]:
> 
> >This patch removes the x86-specific definition of irq_domain and replaces
> >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/irqdomain.c:114 irq_domain_add_legacy+0x75/0x150()
> |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/kernel/devicetree.c:367!
> 
> The warning is comming from this piece in irq_domain_add_legacy()
> |for (i = 0; i < size; i++) {
> |                 int irq = first_irq + i;
> |                 struct irq_data *irq_data = irq_get_irq_data(irq);
> | 
> |                 if (WARN_ON(!irq_data || irq_data->domain)) {
> 
> irq_data is NULL here.
> 
> |                         mutex_unlock(&irq_domain_mutex);
> |                         of_node_put(domain->of_node);
> |                         kfree(domain);
> |                         return NULL;
> |                 }
> |         }
> | 
> 
> 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() => io_apic_setup_irq_pin() =>
> 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.  The 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.  Inside the map hook is preferred, but having some
configured and some not at initialization time does make it difficult

g.


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