On Tue, Nov 26, 2013 at 11:34 AM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: > On Mon, Nov 25, 2013 at 7:38 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: >> 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? > hope you are happy with this one: -v3: use atomic operations to prevent racing that Rafael and Bjorn concern. Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx> --- drivers/pci/probe.c | 2 ++ drivers/pci/remove.c | 8 +++++--- include/linux/pci.h | 1 + 3 files changed, 8 insertions(+), 3 deletions(-) Index: linux-2.6/drivers/pci/remove.c =================================================================== --- linux-2.6.orig/drivers/pci/remove.c +++ linux-2.6/drivers/pci/remove.c @@ -20,9 +20,11 @@ static void pci_stop_dev(struct pci_dev static void pci_destroy_dev(struct pci_dev *dev) { - device_del(&dev->dev); - - put_device(&dev->dev); + if (atomic_inc_and_test(&dev->removed_count)) { + device_del(&dev->dev); + put_device(&dev->dev); + } else + atomic_dec(&dev->removed_count); } void pci_remove_bus(struct pci_bus *bus) Index: linux-2.6/include/linux/pci.h =================================================================== --- linux-2.6.orig/include/linux/pci.h +++ linux-2.6/include/linux/pci.h @@ -316,6 +316,7 @@ struct pci_dev { struct resource resource[DEVICE_COUNT_RESOURCE]; /* I/O and memory regions + expansion ROMs */ bool match_driver; /* Skip attaching driver */ + atomic_t removed_count; /* pci_destroy_dev is called */ /* These fields are used by common fixups */ unsigned int transparent:1; /* Subtractive decode PCI bridge */ unsigned int multifunction:1;/* Part of multi-function device */ Index: linux-2.6/drivers/pci/probe.c =================================================================== --- linux-2.6.orig/drivers/pci/probe.c +++ linux-2.6/drivers/pci/probe.c @@ -1398,6 +1398,8 @@ void pci_device_add(struct pci_dev *dev, dev->match_driver = false; ret = device_add(&dev->dev); WARN_ON(ret < 0); + + atomic_set(&dev->removed_count, -1); } struct pci_dev *__ref pci_scan_single_device(struct pci_bus *bus, int devfn) -- 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
