> -----Original Message----- > From: Bjorn Helgaas [mailto:helgaas@xxxxxxxxxx] > Sent: Tuesday, September 27, 2016 12:30 PM > To: Long Li <longli@xxxxxxxxxxxxx> > Cc: KY Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang Zhang > <haiyangz@xxxxxxxxxxxxx>; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; > devel@xxxxxxxxxxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; Long Li <longli@xxxxxxxxxxxxx> > Subject: Re: [PATCH 1/2 v2] pci-hyperv: properly handle pci bus remove > > On Wed, Sep 14, 2016 at 07:10:01PM -0700, Long Li wrote: > > From: Long Li <longli@xxxxxxxxxxxxx> > > > > hv_pci_devices_present is called in hv_pci_remove when we remove a PCI > device from host (e.g. by disabling SRIOV on a device). In hv_pci_remove, > the bus is already removed before the call, so we don't need to rescan the > bus in the workqueue scheduled from hv_pci_devices_present. By > introducing status hv_pcibus_removed, we can avoid this situation. > > > > The patch fixes the following kernel panic. > > > > [ 383.853124] Workqueue: events pci_devices_present_work [pci_hyperv] > > [ 383.853124] task: ffff88007f5f8000 ti: ffff88007f600000 task.ti: > > ffff88007f600000 > > [ 383.853124] RIP: 0010:[<ffffffff81349806>] [<ffffffff81349806>] > > pci_is_pcie+0x6/0x20 > > [ 383.853124] RSP: 0018:ffff88007f603d38 EFLAGS: 00010206 [ > > 383.853124] RAX: ffff88007f5f8000 RBX: 642f3d4854415056 RCX: > > ffff88007f603fd8 > > [ 383.853124] RDX: 0000000000000000 RSI: 0000000000000000 RDI: > > 642f3d4854415056 > > [ 383.853124] RBP: ffff88007f603d68 R08: 0000000000000246 R09: > > ffffffffa045eb9e > > [ 383.853124] R10: ffff88007b419a80 R11: ffffea0001c0ef40 R12: > > ffff880003ee1c00 > > [ 383.853124] R13: 63702f30303a3137 R14: 0000000000000000 R15: > > 0000000000000246 > > [ 383.853124] FS: 0000000000000000(0000) GS:ffff88007b400000(0000) > > knlGS:0000000000000000 > > [ 383.853124] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ > > 383.853124] CR2: 00007f68b3f52350 CR3: 0000000003546000 CR4: > > 00000000000406f0 > > [ 383.853124] DR0: 0000000000000000 DR1: 0000000000000000 DR2: > > 0000000000000000 > > [ 383.853124] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: > > 0000000000000400 > > [ 383.853124] Stack: > > [ 383.853124] ffff88007f603d68 ffffffff8134db17 0000000000000008 > > ffff880003ee1c00 > > [ 383.853124] 63702f30303a3137 ffff880003d8edb8 ffff88007f603da0 > > ffffffff8134ee2d [ 383.853124] ffff880003d8ed00 ffff88007f603dd8 > > ffff880075fec320 > > ffff880003d8edb8 > > [ 383.853124] Call Trace: > > [ 383.853124] [<ffffffff8134db17>] ? pci_scan_slot+0x27/0x140 [ > > 383.853124] [<ffffffff8134ee2d>] pci_scan_child_bus+0x3d/0x150 [ > > 383.853124] [<ffffffffa045ef5a>] > > pci_devices_present_work+0x3ea/0x400 [pci_hyperv] [ 383.853124] > > [<ffffffff810a682b>] process_one_work+0x17b/0x470 [ 383.853124] > > [<ffffffff810a7666>] worker_thread+0x126/0x410 [ 383.853124] > > [<ffffffff810a7540>] ? rescuer_thread+0x460/0x460 [ 383.853124] > > [<ffffffff810aee1f>] kthread+0xcf/0xe0 [ 383.853124] > > [<ffffffff810aed50>] ? > > kthread_create_on_node+0x140/0x140 > > [ 383.853124] [<ffffffff81699958>] ret_from_fork+0x58/0x90 [ > > 383.853124] [<ffffffff810aed50>] ? > > kthread_create_on_node+0x140/0x140 > > [ 383.853124] Code: 89 e5 5d 25 f0 00 00 00 c1 f8 04 c3 66 0f 1f 84 > > 00 > > 00 00 00 00 66 66 66 66 90 55 0f b6 47 4a 48 89 e5 5d c3 90 66 66 66 > > 66 > > 90 55 <80> 7f 4a 00 48 89 e5 5d 0f 95 c0 c3 0f 1f 40 00 66 2e 0f 1f 84 > > [ 383.853124] RIP [<ffffffff81349806>] pci_is_pcie+0x6/0x20 [ > > 383.853124] RSP <ffff88007f603d38> > > Personally, I would remove the timestamps and addresses from this trace > because I don't think they contribute to diagnosing the problem. Thanks Bjorn. I will remove those kernel traces and send a v3 patch. > > > Signed-off-by: Long Li <longli@xxxxxxxxxxxxx> > > I'm ready to apply these but am waiting for an ack from the maintainers listed > in MAINTAINERS (feel free to update that if it's out of date). > > > --- > > drivers/pci/host/pci-hyperv.c | 20 +++++++++++++++++--- > > 1 file changed, 17 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/pci/host/pci-hyperv.c > > b/drivers/pci/host/pci-hyperv.c index a8deeca..4a37598 100644 > > --- a/drivers/pci/host/pci-hyperv.c > > +++ b/drivers/pci/host/pci-hyperv.c > > @@ -348,6 +348,7 @@ enum hv_pcibus_state { > > hv_pcibus_init = 0, > > hv_pcibus_probed, > > hv_pcibus_installed, > > + hv_pcibus_removed, > > hv_pcibus_maximum > > }; > > > > @@ -1481,13 +1482,24 @@ static void pci_devices_present_work(struct > work_struct *work) > > put_pcichild(hpdev, hv_pcidev_ref_initial); > > } > > > > - /* Tell the core to rescan bus because there may have been changes. > */ > > - if (hbus->state == hv_pcibus_installed) { > > + switch (hbus->state) { > > + case hv_pcibus_installed: > > + /* > > + * Tell the core to rescan bus > > + * because there may have been changes. > > + */ > > pci_lock_rescan_remove(); > > pci_scan_child_bus(hbus->pci_bus); > > pci_unlock_rescan_remove(); > > - } else { > > + break; > > + > > + case hv_pcibus_init: > > + case hv_pcibus_probed: > > survey_child_resources(hbus); > > + break; > > + > > + default: > > + break; > > } > > > > up(&hbus->enum_sem); > > @@ -2163,6 +2175,7 @@ static int hv_pci_probe(struct hv_device *hdev, > > hbus = kzalloc(sizeof(*hbus), GFP_KERNEL); > > if (!hbus) > > return -ENOMEM; > > + hbus->state = hv_pcibus_init; > > > > /* > > * The PCI bus "domain" is what is called "segment" in ACPI and @@ > > -2305,6 +2318,7 @@ static int hv_pci_remove(struct hv_device *hdev) > > pci_stop_root_bus(hbus->pci_bus); > > pci_remove_root_bus(hbus->pci_bus); > > pci_unlock_rescan_remove(); > > + hbus->state = hv_pcibus_removed; > > } > > > > ret = hv_send_resources_released(hdev); > > -- > > 1.8.5.6 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-pci" > > in the body of a message to majordomo@xxxxxxxxxxxxxxx More > majordomo > > info at > > > https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fvger.k > > ernel.org%2Fmajordomo- > info.html&data=01%7C01%7Clongli%40microsoft.com% > > > 7Cfa9e8dff88df4dfb474808d3e70ca246%7C72f988bf86f141af91ab2d7cd011db > 47% > > > 7C1&sdata=pi7cmLozpu8EqSjH6C0ihAMWtg4FX5Usy9e0PJqpH5Q%3D&reser > ved=0 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
