Re: [PATCH 1/2] PCI: allow pci driver to support only dynids

From: Jean Delvare
Date: Wed Nov 26 2008 - 03:28:38 EST


Hi Chris,

On Tue, 25 Nov 2008 19:36:10 -0800, Chris Wright wrote:
> commit b41d6cf38e27 (PCI: Check dynids driver_data value for validity)
> requires all drivers to include an id table to try and match
> driver_data. Before validating driver_data check driver has an id
> table.

Sorry for missing this case.

> Cc: Jean Delvare <khali@xxxxxxxxxxxx>
> Cc: Milton Miller <miltonm@xxxxxxx>
> Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
> ---
> drivers/pci/pci-driver.c | 20 +++++++++++---------
> 1 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index b4cdd69..0a5edbe 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -48,7 +48,7 @@ store_new_id(struct device_driver *driver, const char *buf, size_t count)
> subdevice=PCI_ANY_ID, class=0, class_mask=0;
> unsigned long driver_data=0;
> int fields=0;
> - int retval;
> + int retval=0;
>
> fields = sscanf(buf, "%x %x %x %x %x %x %lx",
> &vendor, &device, &subvendor, &subdevice,
> @@ -58,16 +58,18 @@ store_new_id(struct device_driver *driver, const char *buf, size_t count)
>
> /* Only accept driver_data values that match an existing id_table
> entry */
> - retval = -EINVAL;
> - while (ids->vendor || ids->subvendor || ids->class_mask) {
> - if (driver_data == ids->driver_data) {
> - retval = 0;
> - break;
> + if (ids) {
> + retval = -EINVAL;
> + while (ids->vendor || ids->subvendor || ids->class_mask) {
> + if (driver_data == ids->driver_data) {
> + retval = 0;
> + break;
> + }
> + ids++;
> }
> - ids++;
> + if (retval) /* No match */
> + return retval;
> }
> - if (retval) /* No match */
> - return retval;
>
> dynid = kzalloc(sizeof(*dynid), GFP_KERNEL);
> if (!dynid)

Do we really want to let the user add a new id to a driver which didn't
have any? Wouldn't it be safer to simply not create the new_id sysfs
file if driver->id_table is NULL? That's a one-line change:

Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
---
drivers/pci/pci-driver.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- linux-2.6.28-rc6.orig/drivers/pci/pci-driver.c 2008-10-24 09:28:14.000000000 +0200
+++ linux-2.6.28-rc6/drivers/pci/pci-driver.c 2008-11-26 09:23:46.000000000 +0100
@@ -113,7 +113,7 @@ static int
pci_create_newid_file(struct pci_driver *drv)
{
int error = 0;
- if (drv->probe != NULL)
+ if (drv->probe != NULL && drv->id_table != NULL)
error = driver_create_file(&drv->driver, &driver_attr_new_id);
return error;
}

As a side note, I am curious what PCI driver we do have which has
driver->probe defined but no driver->id_table. Did you hit an actual
issue or are you fixing a theoretical one?

Thanks,
--
Jean Delvare
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