On Feb 2, 2007, at 8:35 PM, Chris Wright wrote:
-stable review patch. If anyone has any objections, please let us
know.
------------------
We just updated this for mainline to remove the printks. I'd prefer
to see that version of this patch go in.
- k
From: Ard van Breemen <[email protected]>
The pci_find_subsys gets called very early by obsolete ide setup
parameters.
This is a bogus call since pci is not initialized yet, so the list
is empty.
But in the mean time, interrupts get enabled by down_read. This
can result in
a kernel panic when the irq controller gets initialized.
This patch checks if the device list is empty before taking the
semaphore, and
hence will not enable irq's. Furthermore it will inform that it is
called
while pci_devices is empty as a reminder that the ide code needs to
be fixed.
The pci_get_subsys can get called in the same manner, and as such
is patched
in the same manner.
[[email protected]: cleanups]
Signed-off-by: Ard van Breemen <[email protected]>
Cc: Greg KH <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Chris Wright <[email protected]>
---
This is the other half of the fix for bug #7505
drivers/pci/search.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
--- linux-2.6.19.2.orig/drivers/pci/search.c
+++ linux-2.6.19.2/drivers/pci/search.c
@@ -193,6 +193,18 @@ static struct pci_dev * pci_find_subsys(
struct pci_dev *dev;
WARN_ON(in_interrupt());
+
+ /*
+ * pci_find_subsys() can be called on the ide_setup() path, super-
early
+ * in boot. But the down_read() will enable local interrupts, which
+ * can cause some machines to crash. So here we detect and flag
that
+ * situation and bail out early.
+ */
+ if (unlikely(list_empty(&pci_devices))) {
+ printk(KERN_INFO "pci_find_subsys() called while pci_devices "
+ "is still empty\n");
+ return NULL;
+ }
down_read(&pci_bus_sem);
n = from ? from->global_list.next : pci_devices.next;
@@ -259,6 +271,18 @@ pci_get_subsys(unsigned int vendor, unsi
struct pci_dev *dev;
WARN_ON(in_interrupt());
+
+ /*
+ * pci_get_subsys() can potentially be called by drivers super-early
+ * in boot. But the down_read() will enable local interrupts, which
+ * can cause some machines to crash. So here we detect and flag
that
+ * situation and bail out early.
+ */
+ if (unlikely(list_empty(&pci_devices))) {
+ printk(KERN_NOTICE "pci_get_subsys() called while pci_devices "
+ "is still empty\n");
+ return NULL;
+ }
down_read(&pci_bus_sem);
n = from ? from->global_list.next : pci_devices.next;
--
-
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