diff options
author | Yijing Wang <wangyijing@huawei.com> | 2013-01-11 10:15:54 +0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-01-27 20:47:43 -0800 |
commit | 5f3e5a32d083008c1ad850375d24fc85a27803e4 (patch) | |
tree | 4d440fea7cac28d605b81e3fcd934f56a8929813 /drivers/pci/hotplug | |
parent | 11cfb2b163f483a4c97e5a229635d0f6b23bd5ac (diff) |
PCI: pciehp: Use per-slot workqueues to avoid deadlock
commit c2be6f93b383c873a4f9d521afa49b1b67d06085 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/pci/hotplug')
-rw-r--r-- | drivers/pci/hotplug/pciehp.h | 2 | ||||
-rw-r--r-- | drivers/pci/hotplug/pciehp_core.c | 11 | ||||
-rw-r--r-- | drivers/pci/hotplug/pciehp_ctrl.c | 8 | ||||
-rw-r--r-- | drivers/pci/hotplug/pciehp_hpc.c | 11 |
4 files changed, 17 insertions, 15 deletions
diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h index 4b7cce1de6e..a321b77a5e8 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 { diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c index 365c6b96c64..9e39df96956 100644 --- a/drivers/pci/hotplug/pciehp_core.c +++ b/drivers/pci/hotplug/pciehp_core.c @@ -42,7 +42,6 @@ bool pciehp_debug; bool pciehp_poll_mode; int pciehp_poll_time; bool pciehp_force; -struct workqueue_struct *pciehp_wq; #define DRIVER_VERSION "0.4" #define DRIVER_AUTHOR "Dan Zink <dan.zink@compaq.com>, Greg Kroah-Hartman <greg@kroah.com>, Dely Sy <dely.l.sy@intel.com>" @@ -340,18 +339,13 @@ static int __init pcied_init(void) { int retval = 0; - pciehp_wq = alloc_workqueue("pciehp", 0, 0); - if (!pciehp_wq) - return -ENOMEM; - pciehp_firmware_init(); retval = pcie_port_service_register(&hpdriver_portdrv); dbg("pcie_port_service_register = %d\n", retval); info(DRIVER_DESC " version: " DRIVER_VERSION "\n"); - if (retval) { - destroy_workqueue(pciehp_wq); + if (retval) dbg("Failure to register service\n"); - } + return retval; } @@ -359,7 +353,6 @@ static void __exit pcied_cleanup(void) { dbg("unload_pciehpd()\n"); pcie_port_service_unregister(&hpdriver_portdrv); - destroy_workqueue(pciehp_wq); info(DRIVER_DESC " version: " DRIVER_VERSION " unloaded\n"); } diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c index 27f44295a65..38f01867917 100644 --- a/drivers/pci/hotplug/pciehp_ctrl.c +++ b/drivers/pci/hotplug/pciehp_ctrl.c @@ -49,7 +49,7 @@ static int queue_interrupt_event(struct slot *p_slot, u32 event_type) info->p_slot = p_slot; INIT_WORK(&info->work, interrupt_event_handler); - queue_work(pciehp_wq, &info->work); + queue_work(p_slot->wq, &info->work); return 0; } @@ -344,7 +344,7 @@ void pciehp_queue_pushbutton_work(struct work_struct *work) kfree(info); goto out; } - queue_work(pciehp_wq, &info->work); + queue_work(p_slot->wq, &info->work); out: mutex_unlock(&p_slot->lock); } @@ -377,7 +377,7 @@ static void handle_button_press_event(struct slot *p_slot) if (ATTN_LED(ctrl)) pciehp_set_attention_status(p_slot, 0); - queue_delayed_work(pciehp_wq, &p_slot->work, 5*HZ); + queue_delayed_work(p_slot->wq, &p_slot->work, 5*HZ); break; case BLINKINGOFF_STATE: case BLINKINGON_STATE: @@ -439,7 +439,7 @@ static void handle_surprise_event(struct slot *p_slot) else p_slot->state = POWERON_STATE; - queue_work(pciehp_wq, &info->work); + queue_work(p_slot->wq, &info->work); } static void interrupt_event_handler(struct work_struct *work) diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c index a960faec102..9dd2c01a2e1 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -874,23 +874,32 @@ static void pcie_shutdown_notification(struct controller *ctrl) static int pcie_init_slot(struct controller *ctrl) { struct slot *slot; + char name[32]; slot = kzalloc(sizeof(*slot), GFP_KERNEL); if (!slot) return -ENOMEM; + snprintf(name, sizeof(name), "pciehp-%u", PSN(ctrl)); + slot->wq = alloc_workqueue(name, 0, 0); + if (!slot->wq) + goto abort; + slot->ctrl = ctrl; mutex_init(&slot->lock); INIT_DELAYED_WORK(&slot->work, pciehp_queue_pushbutton_work); ctrl->slot = slot; return 0; +abort: + kfree(slot); + return -ENOMEM; } static void pcie_cleanup_slot(struct controller *ctrl) { struct slot *slot = ctrl->slot; cancel_delayed_work(&slot->work); - flush_workqueue(pciehp_wq); + destroy_workqueue(slot->wq); kfree(slot); } |