From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f46.google.com ([209.85.160.46]:44707 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752024Ab2H0PGJ (ORCPT ); Mon, 27 Aug 2012 11:06:09 -0400 Message-ID: <503B8CD4.8070802@gmail.com> Date: Mon, 27 Aug 2012 23:05:56 +0800 From: Jiang Liu MIME-Version: 1.0 To: Huang Ying CC: Yijing Wang , Bjorn Helgaas , Rusty Russell , Mauro Carvalho Chehab , PCI , Hanjun Guo , linux-kernel@vger.kernel.org Subject: Re: [RESEND BUGFIX PATCH 1/3] PCI/AER: fix pci_ops return NULL when hotplug a pci bus which was doing aer error inject References: <1344685946-8172-1-git-send-email-wangyijing@huawei.com> <5038A210.4030005@huawei.com> <1346030599.6279.315.camel@yhuang-dev> In-Reply-To: <1346030599.6279.315.camel@yhuang-dev> Content-Type: text/plain; charset=UTF-8 Sender: linux-pci-owner@vger.kernel.org List-ID: Is it ok to ignore such a case? After all, aer_inject is just a test tool:) It's not worth to change the core logic for such a corner case. --Gerry On 08/27/2012 09:23 AM, Huang Ying wrote: > On Sat, 2012-08-25 at 17:59 +0800, Yijing Wang wrote: >> When we inject aer errors to the target pci device by aer_inject module, the pci_ops of pci >> bus which the target device is on will be assign to pci_ops_aer.So if the target pci device >> is a bridge, once we hotplug the pci bus(child bus) which the target device bridges to, child >> bus's pci_ops will be assigned to pci_ops_aer too.Now every access to the child bus's device >> will result to system panic, because it return NULL pci_ops in pci_read_aer. >> This patch fix this. >> >> CallTrace: >> bash[5908]: NaT consumption 17179869216 [1] >> Modules linked in: aer_inject cpufreq_conservative cpufreq_userspace cpufreq_pow >> ersave acpi_cpufreq binfmt_misc fuse nls_iso8859_1 loop ipmi_si(+) ipmi_devintf >> ipmi_msghandler dm_mod ppdev iTCO_wdt iTCO_vendor_support sg igb parport_pc i2c_ >> i801 mptctl i2c_core serio_raw hid_generic lpc_ich mfd_core parport button conta >> iner usbhid hid uhci_hcd ehci_hcd usbcore usb_common sd_mod crc_t10dif ext3 mbca >> che jbd fan processor ide_pci_generic ide_core ata_piix libata mptsas mptscsih m >> ptbase scsi_transport_sas scsi_mod thermal thermal_sys hwmon >> >> Pid: 5908, CPU 9, comm: bash >> psr : 00001010085a2010 ifs : 800000000000048e ip : [] Not >> tainted (3.5.0-rc6yijing-repo) >> ip is at pci_read_aer+0x330/0x460 [aer_inject] >> unat: 0000000000000000 pfs : 000000000000048e rsc : 0000000000000003 >> rnat: 0000000000000000 bsps: 0000000000000000 pr : 65519aa6a6969aa5 >> ldrs: 0000000000000000 ccv : ffffffff00000001 fpsr: 0009804c8a70033f >> csd : 0000000000000000 ssd : 0000000000000000 >> b0 : a000000220b815b0 b6 : a000000220b81280 b7 : a0000001006d56a0 >> f6 : 1003e0000000000000005 f7 : 1003e0000000000000028 >> f8 : 1003e00000000000000c8 f9 : 1003e0000000000000005 >> f10 : 1003e627ec1e2f4c0d8a7 f11 : 1003e0000000000000011 >> r1 : a0000001014e63c0 r2 : 0000000000000738 r3 : 000000000000fffe >> r8 : 0000000000000736 r9 : 0000000000000042 r10 : e000001f08f4c898 >> r11 : 0000000000000000 r12 : e000000f3dfcfdc0 r13 : e000000f3dfc0000 >> r14 : 0000000000000738 r15 : 0000000000004000 r16 : a000000220b827c8 >> r17 : a000000220b827b8 r18 : ffffffffffffff00 r19 : e000000f073b0110 >> r20 : 0000000000000042 r21 : e000000f073b0114 r22 : 0000000000000000 >> r23 : e000000f073b0118 r24 : a0000001009e0e49 r25 : 0000000000000001 >> r26 : 0000000000007041 r27 : e000000f3dfcfde0 r28 : 0000000000000000 >> r29 : e000000f3dfcfc08 r30 : a000000220b827c8 r31 : e000001f074d6000 >> >> Call Trace: >> [] show_stack+0x80/0xa0 >> sp=e000000f3dfcf800 bsp=e000000f3dfc1758 >> [] show_regs+0x640/0x920 >> sp=e000000f3dfcf9d0 bsp=e000000f3dfc1700 >> [] die+0x190/0x2c0 >> sp=e000000f3dfcf9e0 bsp=e000000f3dfc16c0 >> [] die_if_kernel+0x50/0x80 >> sp=e000000f3dfcf9e0 bsp=e000000f3dfc1690 >> [] ia64_fault+0xf0/0x15e0 >> sp=e000000f3dfcf9e0 bsp=e000000f3dfc1640 >> [] ia64_native_leave_kernel+0x0/0x270 >> sp=e000000f3dfcfbf0 bsp=e000000f3dfc1640 >> [] pci_read_aer+0x330/0x460 [aer_inject] >> sp=e000000f3dfcfdc0 bsp=e000000f3dfc15c8 >> [] pci_bus_read_config_dword+0xe0/0x140 >> sp=e000000f3dfcfdc0 bsp=e000000f3dfc1580 >> [] pci_bus_read_dev_vendor_id+0x50/0x200 >> sp=e000000f3dfcfdd0 bsp=e000000f3dfc1530 >> [] pci_scan_single_device+0x90/0x200 >> sp=e000000f3dfcfdd0 bsp=e000000f3dfc14f8 >> [] pci_scan_slot+0xb0/0x320 >> sp=e000000f3dfcfde0 bsp=e000000f3dfc14a8 >> [] pci_scan_child_bus+0x90/0x2e0 >> sp=e000000f3dfcfde0 bsp=e000000f3dfc1468 >> [] pci_scan_bridge+0x540/0xdc0 >> sp=e000000f3dfcfde0 bsp=e000000f3dfc13d0 >> [] pci_scan_child_bus+0x2b0/0x2e0 >> sp=e000000f3dfcfe00 bsp=e000000f3dfc1390 >> [] pci_rescan_bus+0x50/0x220 >> sp=e000000f3dfcfe00 bsp=e000000f3dfc1358 >> [] bus_rescan_store+0xf0/0x160 >> sp=e000000f3dfcfe10 bsp=e000000f3dfc1328 >> [] bus_attr_store+0x70/0xa0 >> sp=e000000f3dfcfe20 bsp=e000000f3dfc12f0 >> [] sysfs_write_file+0x240/0x340 >> sp=e000000f3dfcfe20 bsp=e000000f3dfc1298 >> [] vfs_write+0x1b0/0x3a0 >> sp=e000000f3dfcfe20 bsp=e000000f3dfc1250 >> [] sys_write+0x80/0x100 >> sp=e000000f3dfcfe20 bsp=e000000f3dfc11d0 >> [] ia64_ret_from_syscall+0x0/0x20 >> sp=e000000f3dfcfe30 bsp=e000000f3dfc11d0 >> [] __kernel_syscall_via_break+0x0/0x20 >> sp=e000000f3dfd0000 bsp=e000000f3dfc11d0 >> Disabling lock debugging due to kernel taint >> >> Signed-off-by: Yijing Wang >> Signed-off-by: Jiang Liu >> --- >> drivers/pci/pcie/aer/aer_inject.c | 21 +++++++++++++++++++++ >> 1 files changed, 21 insertions(+), 0 deletions(-) >> >> diff --git a/drivers/pci/pcie/aer/aer_inject.c b/drivers/pci/pcie/aer/aer_inject.c >> index 5222986..fc28785 100644 >> --- a/drivers/pci/pcie/aer/aer_inject.c >> +++ b/drivers/pci/pcie/aer/aer_inject.c >> @@ -109,6 +109,19 @@ static struct aer_error *__find_aer_error_by_dev(struct pci_dev *dev) >> return __find_aer_error((u16)domain, dev->bus->number, dev->devfn); >> } >> >> +static bool pci_is_upstream_bus(struct pci_bus *bus, struct pci_bus *up_bus) >> +{ >> + struct pci_bus *pbus = bus->parent; >> + >> + while (pbus) { >> + if (pbus == up_bus) >> + return true; >> + pbus = pbus->parent; >> + } >> + >> + return false; >> +} >> + >> /* inject_lock must be held before calling */ >> static struct pci_ops *__find_pci_bus_ops(struct pci_bus *bus) >> { >> @@ -118,6 +131,13 @@ static struct pci_ops *__find_pci_bus_ops(struct pci_bus *bus) >> if (bus_ops->bus == bus) >> return bus_ops->ops; >> } >> + >> + /* here can't find bus_ops, fall back to get bus_ops of upstream bus */ >> + list_for_each_entry(bus_ops, &pci_bus_ops_list, list) { >> + if (pci_is_upstream_bus(bus, bus_ops->bus)) >> + return bus_ops->ops; >> + } >> + >> return NULL; >> } >> >> @@ -506,6 +526,7 @@ static struct miscdevice aer_inject_device = { >> .fops = &aer_inject_fops, >> }; >> >> + >> static int __init aer_inject_init(void) >> { >> return misc_register(&aer_inject_device); > > After > > # rmmod aer_inject > > What will happen? > > Best Regards, > Huang Ying > >