diff options
author | Yijing Wang <wangyijing@huawei.com> | 2013-01-11 02:15:54 (GMT) |
---|---|---|
committer | Bjorn Helgaas <bhelgaas@google.com> | 2013-01-12 20:56:33 (GMT) |
commit | c2be6f93b383c873a4f9d521afa49b1b67d06085 (patch) | |
tree | dacb5ae1d88abf8f5e0daec176abdd2710d5555e /drivers/pci/hotplug/pciehp.h | |
parent | d1c3ed669a2d452cacfb48c2d171a1f364dae2ed (diff) | |
download | linux-fsl-qoriq-c2be6f93b383c873a4f9d521afa49b1b67d06085.tar.xz |
PCI: pciehp: Use per-slot workqueues to avoid deadlock
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
Diffstat (limited to 'drivers/pci/hotplug/pciehp.h')
-rw-r--r-- | drivers/pci/hotplug/pciehp.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h index 26ffd3e..2c113de 100644 --- a/drivers/pci/hotplug/pciehp.h +++ b/drivers/pci/hotplug/pciehp.h @@ -44,7 +44,6 @@ extern bool pciehp_poll_mode; extern int pciehp_poll_time; extern bool pciehp_debug; extern bool pciehp_force; -extern struct workqueue_struct *pciehp_wq; #define dbg(format, arg...) \ do { \ @@ -78,6 +77,7 @@ struct slot { struct hotplug_slot *hotplug_slot; struct delayed_work work; /* work for button event */ struct mutex lock; + struct workqueue_struct *wq; }; struct event_info { |