[PATCH] PCI: fix race with pci_walk_bus and pci_destroy_dev
pci_walk_bus has a race with pci_destroy_dev. When cb is called
in pci_walk_bus, pci_destroy_dev might unlink the dev pointed by next.
Later on in the next loop, pointer next becomes NULL and cause
kernel panic.
Below patch against 2.6.17-rc4 fixes it by changing pci_bus_lock (spin_lock)
to pci_bus_sem (rw_semaphore).
Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 27148db..f89dbc3 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -383,9 +383,9 @@
child = pci_alloc_child_bus(parent, dev, busnr);
if (child) {
- spin_lock(&pci_bus_lock);
+ down_write(&pci_bus_sem);
list_add_tail(&child->node, &parent->children);
- spin_unlock(&pci_bus_lock);
+ up_write(&pci_bus_sem);
}
return child;
}
@@ -844,9 +844,9 @@
* and the bus list for fixup functions, etc.
*/
INIT_LIST_HEAD(&dev->global_list);
- spin_lock(&pci_bus_lock);
+ down_write(&pci_bus_sem);
list_add_tail(&dev->bus_list, &bus->devices);
- spin_unlock(&pci_bus_lock);
+ up_write(&pci_bus_sem);
}
struct pci_dev * __devinit
@@ -981,9 +981,10 @@
pr_debug("PCI: Bus %04x:%02x already known\n", pci_domain_nr(b), bus);
goto err_out;
}
- spin_lock(&pci_bus_lock);
+
+ down_write(&pci_bus_sem);
list_add_tail(&b->node, &pci_root_buses);
- spin_unlock(&pci_bus_lock);
+ up_write(&pci_bus_sem);
memset(dev, 0, sizeof(*dev));
dev->parent = parent;
@@ -1023,9 +1024,9 @@
class_dev_reg_err:
device_unregister(dev);
dev_reg_err:
- spin_lock(&pci_bus_lock);
+ down_write(&pci_bus_sem);
list_del(&b->node);
- spin_unlock(&pci_bus_lock);
+ up_write(&pci_bus_sem);
err_out:
kfree(dev);
kfree(b);