[PATCH 1/2] pci-hyperv: properly handle pci bus remove
From: Long Li
Date: Mon Sep 12 2016 - 18:04:42 EST
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>
Signed-off-by: Long Li <longli@xxxxxxxxxxxxx>
---
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 daa5fc3..26f049b 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