From d71374dafbba7ec3f67371d3b7e9f6310a588808 Mon Sep 17 00:00:00 2001 From: Zhang Yanmin Date: Fri, 2 Jun 2006 12:35:43 +0800 Subject: [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 Signed-off-by: Greg Kroah-Hartman --- drivers/pci/bus.c | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-) (limited to 'drivers/pci/bus.c') diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index eed67d9e73bc..723092682023 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -81,9 +81,9 @@ void __devinit pci_bus_add_device(struct pci_dev *dev) { device_add(&dev->dev); - spin_lock(&pci_bus_lock); + down_write(&pci_bus_sem); list_add_tail(&dev->global_list, &pci_devices); - spin_unlock(&pci_bus_lock); + up_write(&pci_bus_sem); pci_proc_attach_device(dev); pci_create_sysfs_dev_files(dev); @@ -125,10 +125,10 @@ void __devinit pci_bus_add_devices(struct pci_bus *bus) */ if (dev->subordinate) { if (list_empty(&dev->subordinate->node)) { - spin_lock(&pci_bus_lock); + down_write(&pci_bus_sem); list_add_tail(&dev->subordinate->node, &dev->bus->children); - spin_unlock(&pci_bus_lock); + up_write(&pci_bus_sem); } pci_bus_add_devices(dev->subordinate); @@ -168,7 +168,7 @@ void pci_walk_bus(struct pci_bus *top, void (*cb)(struct pci_dev *, void *), struct list_head *next; bus = top; - spin_lock(&pci_bus_lock); + down_read(&pci_bus_sem); next = top->devices.next; for (;;) { if (next == &bus->devices) { @@ -180,22 +180,19 @@ void pci_walk_bus(struct pci_bus *top, void (*cb)(struct pci_dev *, void *), continue; } dev = list_entry(next, struct pci_dev, bus_list); - pci_dev_get(dev); if (dev->subordinate) { /* this is a pci-pci bridge, do its devices next */ next = dev->subordinate->devices.next; bus = dev->subordinate; } else next = dev->bus_list.next; - spin_unlock(&pci_bus_lock); - /* Run device routines with the bus unlocked */ + /* Run device routines with the device locked */ + down(&dev->dev.sem); cb(dev, userdata); - - spin_lock(&pci_bus_lock); - pci_dev_put(dev); + up(&dev->dev.sem); } - spin_unlock(&pci_bus_lock); + up_read(&pci_bus_sem); } EXPORT_SYMBOL_GPL(pci_walk_bus); -- cgit v1.2.3