PCI: Fix fakephp deadlock

[thirdparty/kernel/stable.git] / drivers / pci / hotplug / fakephp.c

diff --git a/drivers/pci/hotplug/fakephp.c b/drivers/pci/hotplug/fakephp.c
index 027f6865d7e31cdbf1ce80711f076b66c24cbb8c..02a09d5067573575c624eaed37d034bf3754ddd6 100644 (file)
--- a/drivers/pci/hotplug/fakephp.c
+++ b/drivers/pci/hotplug/fakephp.c
@@ -39,6 +39,7 @@
 #include <linux/init.h>
 #include <linux/string.h>
 #include <linux/slab.h>
+#include <linux/workqueue.h>
 #include "../pci.h"
 
 #if !defined(MODULE)
@@ -63,10 +64,16 @@ struct dummy_slot {
        struct list_head node;
        struct hotplug_slot *slot;
        struct pci_dev *dev;
+       struct work_struct remove_work;
+       unsigned long removed;
 };
 
 static int debug;
 static LIST_HEAD(slot_list);
+static struct workqueue_struct *dummyphp_wq;
+
+static void pci_rescan_worker(struct work_struct *work);
+static DECLARE_WORK(pci_rescan_work, pci_rescan_worker);
 
 static int enable_slot (struct hotplug_slot *slot);
 static int disable_slot (struct hotplug_slot *slot);
@@ -109,7 +116,7 @@ static int add_slot(struct pci_dev *dev)
        slot->name = &dev->dev.bus_id[0];
        dbg("slot->name = %s\n", slot->name);
 
-       dslot = kmalloc(sizeof(struct dummy_slot), GFP_KERNEL);
+       dslot = kzalloc(sizeof(struct dummy_slot), GFP_KERNEL);
        if (!dslot)
                goto error_info;
 
@@ -164,6 +171,14 @@ static void remove_slot(struct dummy_slot *dslot)
                err("Problem unregistering a slot %s\n", dslot->slot->name);
 }
 
+/* called from the single-threaded workqueue handler to remove a slot */
+static void remove_slot_worker(struct work_struct *work)
+{
+       struct dummy_slot *dslot =
+               container_of(work, struct dummy_slot, remove_work);
+       remove_slot(dslot);
+}
+
 /**
  * Rescan slot.
  * Tries hard not to re-enable already existing devices
@@ -267,11 +282,17 @@ static inline void pci_rescan(void) {
        pci_rescan_buses(&pci_root_buses);
 }
 
+/* called from the single-threaded workqueue handler to rescan all pci buses */
+static void pci_rescan_worker(struct work_struct *work)
+{
+       pci_rescan();
+}
 
 static int enable_slot(struct hotplug_slot *hotplug_slot)
 {
        /* mis-use enable_slot for rescanning of the pci bus */
-       pci_rescan();
+       cancel_work_sync(&pci_rescan_work);
+       queue_work(dummyphp_wq, &pci_rescan_work);
        return -ENODEV;
 }
 
@@ -306,6 +327,10 @@ static int disable_slot(struct hotplug_slot *slot)
                err("Can't remove PCI devices with other PCI devices behind it yet.\n");
                return -ENODEV;
        }
+       if (test_and_set_bit(0, &dslot->removed)) {
+               dbg("Slot already scheduled for removal\n");
+               return -ENODEV;
+       }
        /* search for subfunctions and disable them first */
        if (!(dslot->dev->devfn & 7)) {
                for (func = 1; func < 8; func++) {
@@ -328,8 +353,9 @@ static int disable_slot(struct hotplug_slot *slot)
        /* remove the device from the pci core */
        pci_remove_bus_device(dslot->dev);
 
-       /* blow away this sysfs entry and other parts. */
-       remove_slot(dslot);
+       /* queue work item to blow away this sysfs entry and other parts. */
+       INIT_WORK(&dslot->remove_work, remove_slot_worker);
+       queue_work(dummyphp_wq, &dslot->remove_work);
 
        return 0;
 }
@@ -340,6 +366,7 @@ static void cleanup_slots (void)
        struct list_head *next;
        struct dummy_slot *dslot;
 
+       destroy_workqueue(dummyphp_wq);
        list_for_each_safe (tmp, next, &slot_list) {
                dslot = list_entry (tmp, struct dummy_slot, node);
                remove_slot(dslot);
@@ -351,6 +378,10 @@ static int __init dummyphp_init(void)
 {
        info(DRIVER_DESC "\n");
 
+       dummyphp_wq = create_singlethread_workqueue(MY_NAME);
+       if (!dummyphp_wq)
+               return -ENOMEM;
+
        return pci_scan_buses();
 }