[Xen-devel] [Patch] linux: avoid kmalloc while disabling interrupts

[Akio Takebe <takebe_akio@xxxxxxxxxxxxxx>]

Hi,

We should avoid using kmalloc while interrupts is disabled.
kmalloc may sleep.

Signed-off-by: Akio Takebe <takebe_akio@xxxxxxxxxxxxxx>

Best Regards,

Akio Takebe

diff -r e86f9e05144a drivers/xen/pciback/controller.c
--- a/drivers/xen/pciback/controller.c  Mon Sep 08 14:02:13 2008 +0100
+++ b/drivers/xen/pciback/controller.c  Tue Sep 09 16:28:20 2008 +0900
@@ -101,15 +101,15 @@
        unsigned long flags;
        int ret = 0, found = 0;
 
+       /* Look to see if we already have a domain:bus for this controller */
        spin_lock_irqsave(&dev_data->lock, flags);
-
-       /* Look to see if we already have a domain:bus for this controller */
        list_for_each_entry(cntrl_entry, &dev_data->list, list) {
                if (cntrl_entry->controller == dev_controller) {
                        found = 1;
                        break;
                }
        }
+       spin_unlock_irqrestore(&dev_data->lock, flags);
 
        if (!found) {
                cntrl_entry = kmalloc(sizeof(*cntrl_entry), GFP_ATOMIC);
@@ -128,9 +128,10 @@
                        dev_data->next_bus = 0;
                }
 
+               spin_lock_irqsave(&dev_data->lock, flags);
                INIT_LIST_HEAD(&cntrl_entry->dev_list);
-
                list_add_tail(&cntrl_entry->list, &dev_data->list);
+               spin_unlock_irqrestore(&dev_data->lock, flags);
        }
 
        if (PCI_SLOT(cntrl_entry->next_devfn) > PCI_MAX_SLOTS) {
@@ -149,24 +150,24 @@
 
        dev_entry = kmalloc(sizeof(*dev_entry), GFP_ATOMIC);
        if (!dev_entry) {
+               spin_lock_irqsave(&dev_data->lock, flags);
                if (list_empty(&cntrl_entry->dev_list)) {
                        list_del(&cntrl_entry->list);
                        kfree(cntrl_entry);
                }
                ret = -ENOMEM;
+               spin_unlock_irqrestore(&dev_data->lock, flags);
                goto out;
        }
 
        dev_entry->dev = dev;
        dev_entry->devfn = cntrl_entry->next_devfn;
 
+       spin_lock_irqsave(&dev_data->lock, flags);
        list_add_tail(&dev_entry->list, &cntrl_entry->dev_list);
-
        cntrl_entry->next_devfn += PCI_DEVFN(1, 0);
-
+       spin_unlock_irqrestore(&dev_data->lock, flags);
 out:
-       spin_unlock_irqrestore(&dev_data->lock, flags);
-
        /* TODO: Publish virtual domain:bus:slot.func here. */
 
        return ret;

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