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. > P. -- 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
