Re: [PATCH v6 00/11] PCI: Drop duplicated tracking of a pci_dev's bound driver

On Wed, Oct 13, 2021 at 10:51:31AM +0200, Uwe Kleine-König wrote:

On Tue, Oct 12, 2021 at 06:32:12PM -0500, Bjorn Helgaas wrote:

quoted

On Mon, Oct 04, 2021 at 02:59:24PM +0200, Uwe Kleine-König wrote:

quoted

Hello,

this is v6 of the quest to drop the "driver" member from struct pci_dev
which tracks the same data (apart from a constant offset) as dev.driver.

I like this a lot and applied it to pci/driver for v5.16, thanks!

I split some of the bigger patches apart so they only touched one
driver or subsystem at a time.  I also updated to_pci_driver() so it
returns NULL when given NULL, which makes some of the validations
quite a bit simpler, especially in the PM code in pci-driver.c.

OK.

quoted

Full interdiff from this v6 series:

diff --git a/arch/x86/kernel/probe_roms.c b/arch/x86/kernel/probe_roms.c
index deaaef6efe34..36e84d904260 100644
--- a/arch/x86/kernel/probe_roms.c
+++ b/arch/x86/kernel/probe_roms.c

@@ -80,17 +80,15 @@ static struct resource video_rom_resource = {
  */
 static bool match_id(struct pci_dev *pdev, unsigned short vendor, unsigned short device)
 {
+	struct pci_driver *drv = to_pci_driver(pdev->dev.driver);
 	const struct pci_device_id *id;
 
 	if (pdev->vendor == vendor && pdev->device == device)
 		return true;
 
-	if (pdev->dev.driver) {
-		struct pci_driver *drv = to_pci_driver(pdev->dev.driver);
-		for (id = drv->id_table; id && id->vendor; id++)
-			if (id->vendor == vendor && id->device == device)
-				break;
-	}
+	for (id = drv ? drv->id_table : NULL; id && id->vendor; id++)
+		if (id->vendor == vendor && id->device == device)
+			break;
 
 	return id && id->vendor;
 }

diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c
index d997c9c3ebb5..7eb3706cf42d 100644
--- a/drivers/misc/cxl/guest.c
+++ b/drivers/misc/cxl/guest.c

@@ -20,38 +20,38 @@ static void pci_error_handlers(struct cxl_afu *afu,
 				pci_channel_state_t state)
 {
 	struct pci_dev *afu_dev;
+	struct pci_driver *afu_drv;
+	struct pci_error_handlers *err_handler;

These two could be moved into the for loop (where afu_drv was with my
patch already). This is also possible in a few other drivers.

That's true, they could.  I tried to follow the prevailing style in
the file.  At least in cxl, I didn't see any other cases of
declarations being in the minimal scope like that.

Bjorn