On Mon, Nov 25, 2013 at 6:28 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: > Mutliple removing via /sys will call pci_destroy_dev two times. > > | When concurent removing pci devices which are in the same pci subtree > | via sysfs, such as: > | echo -n 1 > /sys/bus/pci/devices/0000\:10\:00.0/remove ; echo -n 1 > > | /sys/bus/pci/devices/0000\:1a\:01.0/remove > | (1a:01.0 device is downstream from the 10:00.0 bridge) > | > | the following warning will show: > | [ 1799.280918] ------------[ cut here ]------------ > | [ 1799.336199] WARNING: CPU: 7 PID: 126 at lib/list_debug.c:53 __list_del_entry+0x63/0xd0() > | [ 1799.433093] list_del corruption, ffff8807b4a7c000->next is LIST_POISON1 (dead000000100100) > | [ 1800.276623] CPU: 7 PID: 126 Comm: kworker/u512:1 Tainted: G W 3.12.0-rc5+ #196 > | [ 1800.508918] Workqueue: sysfsd sysfs_schedule_callback_work > | [ 1800.574703] 0000000000000009 ffff8807adbadbd8 ffffffff8168b26c ffff8807c27d08a8 > | [ 1800.663860] ffff8807adbadc28 ffff8807adbadc18 ffffffff810711dc ffff8807adbadc68 > | [ 1800.753130] ffff8807b4a7c000 ffff8807b4a7c000 ffff8807ad089c00 0000000000000000 > | [ 1800.842282] Call Trace: > | [ 1800.871651] [<ffffffff8168b26c>] dump_stack+0x55/0x76 > | [ 1800.933301] [<ffffffff810711dc>] warn_slowpath_common+0x8c/0xc0 > | [ 1801.005283] [<ffffffff810712c6>] warn_slowpath_fmt+0x46/0x50 > | [ 1801.074081] [<ffffffff8135a343>] __list_del_entry+0x63/0xd0 > | [ 1801.141839] [<ffffffff8135a3c1>] list_del+0x11/0x40 > | [ 1801.201320] [<ffffffff813734da>] pci_remove_bus_device+0x6a/0xe0 > | [ 1801.274279] [<ffffffff8137356e>] pci_stop_and_remove_bus_device+0x1e/0x30 > | [ 1801.356606] [<ffffffff8137b20b>] remove_callback+0x2b/0x40 > | [ 1801.423412] [<ffffffff81251848>] sysfs_schedule_callback_work+0x18/0x60 > | [ 1801.503744] [<ffffffff8108eab5>] process_one_work+0x1f5/0x540 > | [ 1801.573640] [<ffffffff8108ea53>] ? process_one_work+0x193/0x540 > | [ 1801.645616] [<ffffffff8108f2ac>] worker_thread+0x11c/0x370 > | [ 1801.712337] [<ffffffff8108f190>] ? rescuer_thread+0x350/0x350 > | [ 1801.782178] [<ffffffff8109731d>] kthread+0xed/0x100 > | [ 1801.841661] [<ffffffff81097230>] ? kthread_create_on_node+0x160/0x160 > | [ 1801.919919] [<ffffffff8169cc3c>] ret_from_fork+0x7c/0xb0 > | [ 1801.984608] [<ffffffff81097230>] ? kthread_create_on_node+0x160/0x160 > | [ 1802.062825] ---[ end trace d77f2054de000fb7 ]--- > | > | This issue is related to the bug 54411: > | https://bugzilla.kernel.org/show_bug.cgi?id=54411 > > Add is_removed to record if pci_destroy_dev is called already. > > During second calling, still have extra dev ref hold via > device_schedule_call, so we are safe to check dev->is_removed. > > It fixs the problem In Gu's test. > > -v2: add partial changelog from Gu Zheng <guz.fnst@xxxxxxxxxxxxxx> > refresh after patch of moving device_del from Rafael. > > Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx> > --- > drivers/pci/remove.c | 8 +++++--- > include/linux/pci.h | 1 + > 2 files changed, 6 insertions(+), 3 deletions(-) > > diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c > index f452148..b090cec 100644 > --- a/drivers/pci/remove.c > +++ b/drivers/pci/remove.c > @@ -20,9 +20,11 @@ static void pci_stop_dev(struct pci_dev *dev) > > static void pci_destroy_dev(struct pci_dev *dev) > { > - device_del(&dev->dev); > - > - put_device(&dev->dev); > + if (!dev->is_removed) { > + device_del(&dev->dev); > + dev->is_removed = 1; As Rafael pointed out, this looks like a race. What prevents two concurrent calls to pci_destroy_dev() from seeing "dev->is_removed == 0" and both calling device_del() on the same device? > + put_device(&dev->dev); > + } > } > > void pci_remove_bus(struct pci_bus *bus) > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 1084a15..ccb316d 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -321,6 +321,7 @@ struct pci_dev { > unsigned int multifunction:1;/* Part of multi-function device */ > /* keep track of device state */ > unsigned int is_added:1; > + unsigned int is_removed:1; /* pci_destroy_dev is called */ > unsigned int is_busmaster:1; /* device is busmaster */ > unsigned int no_msi:1; /* device may not use msi */ > unsigned int block_cfg_access:1; /* config space access is blocked */ > -- > 1.8.1.4 > -- 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
