Re: [PATCH] acpi, acpi_pci_irq_enable must return an error if ACPI cannot map an IRQ.

[Prarit Bhargava <prarit@redhat.com>]

On 07/25/2013 05:57 AM, Prarit Bhargava wrote:
> 
> 
> On 07/24/2013 08:01 PM, Prarit Bhargava wrote:
>>
>>
>> On 07/24/2013 07:35 PM, Rafael J. Wysocki wrote:
>>> On Monday, July 15, 2013 10:57:40 AM Prarit Bhargava wrote:
>>>> Driver probe's currently do the following
>>>>
>>>> 	pci_enable_device();
>>>> 	/* ... do some other init stuff, and eventually call ... */
>>>> 	request_irq();
>>>>
>>>> After pci_enable_device() is called it is assumed that the device's irq
>>>> value (pci_dev->irq) has been appropriately set on success.  This value
>>>> is passed into the request_irq() call.
>>>>
>>>> In the case that ACPI is used to determine the irq value, it is possible
>>>> that the ACPI IRQ look up for a specific device fails and success is
>>>> returned by pci_enable_device().
>>>>
>>>> The call sequence is:
>>>>
>>>> pci_enable_device();
>>>> 	-> pci_enable_device_flags();
>>>> 		->do_pci_enable_device();
>>>> 			-> pcibios_enable_device() which, if the device
>>>> 			   does not use MSI calls
>>>> 			   -> pcibios_enable_irq() which maps to
>>>> 			      acpi_pci_irq_enable()
>>>> 				-> acpi_pci_irq_lookup()
>>>>
>>>> If acpi_pci_irq_lookup() cannot map the device's IRQ value it returns NULL
>>>> as an error.  The error is returned to acpi_pci_irq_enable(), but is not
>>>> propagated further.  This can result in the driver returning success for
>>>> pci_enable_device() and the driver probe attempting to call request_irq()
>>>> with dev->irq = 0.
>>>>
>>>> This patch modifies acpi_pci_irq_enable() to return an error in the case
>>>> that an entry is not found in the ACPI tables.
>>>
>>> Is there any known system on which this leads to observable misbehavior?
>>>
>>> If so, what's that system?
>>>
>>
>> Dell PowerEdge 840.  The end result is an genirq warning about the irq flags of
>> irq 0:
>>
>> [   14.126845] i801_smbus 0000:00:1f.3: can't derive routing for PCI INT B
>> [   14.133473] i801_smbus 0000:00:1f.3: PCI INT B: no GSI
>> [   14.795122] genirq: Flags mismatch irq 0. 00000080 (i801_smbus) vs. 00015a20
>> (timer)
>> [   14.796037] CPU: 0 PID: 427 Comm: systemd-udevd Tainted: G        W
>> --------------   3.10.0-0.rc4.60.el7.x86_64.debug #1
>> [   14.796037] Hardware name: Dell Computer Corporation PowerEdge 840/0RH822,
>> BIOS A05 10/04/2007
>> [   14.796037]  ffff880075643b80 ffff88007a743aa8 ffffffff816b8bbd ffff88007a743af8
>> [   14.796037]  ffffffff8111ed8d ffffffff811bf5d1 0000000000000296 ffff880075b93800
>> [   14.796037]  ffffffffa03d2240 0000000000000080 0000000000000000 ffff88007ad7e000
>> [   14.796037] Call Trace:
>> [   14.796037]  [<ffffffff816b8bbd>] dump_stack+0x19/0x1b
>> [   14.796037]  [<ffffffff8111ed8d>] __setup_irq+0x51d/0x550
>> [   14.796037]  [<ffffffff811bf5d1>] ? kmem_cache_alloc_trace+0x111/0x340
>> [   14.796037]  [<ffffffffa03d2240>] ? i801_check_pre.isra.6+0xe0/0xe0 [i2c_i801]
>> [   14.796037]  [<ffffffff8111ef1c>] request_threaded_irq+0xcc/0x170
>> [   14.796037]  [<ffffffffa03d388d>] i801_probe+0x34d/0x52c [i2c_i801]
>> [   14.796037]  [<ffffffff810ddecd>] ? trace_hardirqs_on+0xd/0x10
>> [   14.796037]  [<ffffffff813876be>] local_pci_probe+0x3e/0x70
>> [   14.796037]  [<ffffffff813889a1>] pci_device_probe+0x111/0x120
>> [   14.796037]  [<ffffffff8144ff77>] driver_probe_device+0x87/0x390
>> [   14.796037]  [<ffffffff81450353>] __driver_attach+0x93/0xa0
>> [   14.796037]  [<ffffffff814502c0>] ? __device_attach+0x40/0x40
>> [   14.796037]  [<ffffffff8144de93>] bus_for_each_dev+0x63/0xa0
>> [   14.796037]  [<ffffffff8144f9ae>] driver_attach+0x1e/0x20
>> [   14.796037]  [<ffffffff8144f540>] bus_add_driver+0x1f0/0x2a0
>> [   14.796037]  [<ffffffffa03d8000>] ? 0xffffffffa03d7fff
>> [   14.796037]  [<ffffffff814509d1>] driver_register+0x71/0x150
>> [   14.796037]  [<ffffffffa03d8000>] ? 0xffffffffa03d7fff
>> [   14.796037]  [<ffffffff81387540>] __pci_register_driver+0x60/0x70
>> [   14.796037]  [<ffffffffa03d80af>] i2c_i801_init+0xaf/0x1000 [i2c_i801]
>> [   14.796037]  [<ffffffffa03d8000>] ? 0xffffffffa03d7fff
>> [   14.796037]  [<ffffffff810020e2>] do_one_initcall+0xe2/0x1a0
>> [   14.796037]  [<ffffffff810ee09f>] load_module+0xf4f/0x14d0
>> [   14.796037]  [<ffffffff81375d20>] ? ddebug_proc_write+0xf0/0xf0
>> [   14.796037]  [<ffffffff8136088d>] ? trace_hardirqs_off_thunk+0x3a/0x3c
>> [   14.796037]  [<ffffffff810ee6e1>] SyS_init_module+0xc1/0x110
>> [   14.796037]  [<ffffffff816ca299>] system_call_fastpath+0x16/0x1b
>>
> 
> Rafael,
> 
> One other thing -- the core issue here is that the BIOS is broken and does not
> supply an ACPI entry for the IRQ.  I think the kernel should do a better job of
> reacting to that instead of just continuing down a broken path.
> 
> In either case, the end result is the same -- the i801 driver does not load, but
> with my patch the warning is not displayed, which IMO is the correct way to fail.
> 
> P.

Hey Rafael,

I know you're busy but I was just wondering if this was queued up anywhere or if
you had any other questions?

Thanks,

P.