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c2be6f93b3
When we have a hotplug-capable PCIe port with a second hotplug-capable
PCIe port below it, removing the device below the upstream port causes
a deadlock.
The deadlock happens because we use the pciehp_wq workqueue to run
pciehp_power_thread(), which uses pciehp_disable_slot() to remove devices
below the upstream port. When we remove the downstream PCIe port, we call
pciehp_remove(), the pciehp driver's .remove() method. That calls
flush_workqueue(pciehp_wq), which deadlocks because the
pciehp_power_thread() work item is still running.
This patch avoids the deadlock by creating a workqueue for every PCIe port
and removing the single shared workqueue.
Here's the call path that leads to the deadlock:
pciehp_queue_pushbutton_work
queue_work(pciehp_wq) # queue pciehp_power_thread
...
pciehp_power_thread
pciehp_disable_slot
remove_board
pciehp_unconfigure_device
pci_stop_and_remove_bus_device
...
pciehp_remove # pciehp driver .remove method
pciehp_release_ctrl
pcie_cleanup_slot
flush_workqueue(pciehp_wq)
This is fairly urgent because it can be caused by simply unplugging a
Thunderbolt adapter, as reported by Daniel below.
[bhelgaas: changelog]
Reference: http://lkml.kernel.org/r/CAMVG2ssiRgcTD1bej2tkUUfsWmpL5eNtPcNif9va2-Gzb2u8nQ@mail.gmail.com
Reported-and-tested-by: Daniel J Blueman <daniel@quora.org>
Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org
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| .. | ||
| acpi_pcihp.c | ||
| acpiphp_core.c | ||
| acpiphp_glue.c | ||
| acpiphp_ibm.c | ||
| acpiphp.h | ||
| cpci_hotplug_core.c | ||
| cpci_hotplug_pci.c | ||
| cpci_hotplug.h | ||
| cpcihp_generic.c | ||
| cpcihp_zt5550.c | ||
| cpcihp_zt5550.h | ||
| cpqphp_core.c | ||
| cpqphp_ctrl.c | ||
| cpqphp_nvram.c | ||
| cpqphp_nvram.h | ||
| cpqphp_pci.c | ||
| cpqphp_sysfs.c | ||
| cpqphp.h | ||
| ibmphp_core.c | ||
| ibmphp_ebda.c | ||
| ibmphp_hpc.c | ||
| ibmphp_pci.c | ||
| ibmphp_res.c | ||
| ibmphp.h | ||
| Kconfig | ||
| Makefile | ||
| pci_hotplug_core.c | ||
| pciehp_acpi.c | ||
| pciehp_core.c | ||
| pciehp_ctrl.c | ||
| pciehp_hpc.c | ||
| pciehp_pci.c | ||
| pciehp.h | ||
| pcihp_skeleton.c | ||
| pcihp_slot.c | ||
| rpadlpar_core.c | ||
| rpadlpar_sysfs.c | ||
| rpadlpar.h | ||
| rpaphp_core.c | ||
| rpaphp_pci.c | ||
| rpaphp_slot.c | ||
| rpaphp.h | ||
| s390_pci_hpc.c | ||
| sgi_hotplug.c | ||
| shpchp_core.c | ||
| shpchp_ctrl.c | ||
| shpchp_hpc.c | ||
| shpchp_pci.c | ||
| shpchp_sysfs.c | ||
| shpchp.h | ||