-stable review patch. If anyone has any objections, please let us know.
------------------
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;
--
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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* Kumar Gala ([email protected]) wrote:
>
> 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.
Thanks, I was able to fold that minor simplification in.
-chris