Re: [PATCH] xen/pcifront: move xenstore config scanning into sub-function

From: Juergen Gross
Date: Thu Oct 06 2022 - 11:02:06 EST

On 06.10.22 15:29, Jason Andryuk wrote:
On Thu, Oct 6, 2022 at 5:29 AM Juergen Gross <jgross@xxxxxxxx> wrote:

pcifront_try_connect() and pcifront_attach_devices() share a large
chunk of duplicated code for reading the config information from
Xenstore, which only differs regarding a function call.

Put that code into a new sub-function. While at it fix the error
reporting in case the root-xx node had the wrong format.

As the return value of pcifront_try_connect() and
pcifront_attach_devices() are not used anywhere make those functions
return void. As an additional bonus this removes the dubious return
of -EFAULT in case of an unexpected driver state.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
drivers/pci/xen-pcifront.c | 133 +++++++++++--------------------------
1 file changed, 40 insertions(+), 93 deletions(-)

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 689271c4245c..a68e47dcdd7e 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -819,76 +819,79 @@ static int pcifront_publish_info(struct pcifront_device *pdev)

err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend,
"root_num", "%d", &num_roots);
if (err == -ENOENT) {
xenbus_dev_error(pdev->xdev, err,
"No PCI Roots found, trying 0000:00");
- err = pcifront_scan_root(pdev, 0, 0);
+ if (rescan)
+ err = pcifront_rescan_root(pdev, 0, 0);
+ else
+ err = pcifront_scan_root(pdev, 0, 0);

Early in pcifront_rescan_root(), we have:

b = pci_find_bus(domain, bus);
if (!b)
/* If the bus is unknown, create it. */
return pcifront_scan_root(pdev, domain, bus);

pcifront_scan_root() does some allocation, but the later scanning
matches that of pcifront_rescan_root(). So I think we can just always
call pcifront_rescan_root() and it should do the right thing. That
drops the need for the rescan boolean.

Hmm, with some more pcifront_rescan_root() adaption this will make it
possible to drop even more code (i.e. the CONFIG_PCI_DOMAINS check in
pcifront_rescan_root(), as the one in pcifront_scan_root() would be
enough then).

I'll send out V2 soon.

Regardless of the above idea:

Reviewed-by: Jason Andryuk <jandryuk@xxxxxxxxx>

Thanks. As I'm about to change the patch, I'll drop the R-b.


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