On Thursday, July 25, 2013 05:57:19 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. I agree. I wanted to know how serious the problem was so as to determine the urgency of the fix. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
