[PATCH next] xen: pcifront: Process failure for pcifront_(re)scan_root()

[Chen Gang]

When pcifront_rescan_root() or pcifront_scan_root() fails, need return
error code, neither set XenbusStateConnected state, just like the other
areas have done.

For pcifront_rescan_root(), it will return error code ("num_roots = 0;",
skip xenbus_switch_state return value).

For pcifront_scan_root(), it will return 0 ("num_roots = 0;", set 0 by
the return value of xenbus_switch_state, which always return 0, at
present).

Signed-off-by: Chen Gang <***@gmail.com>
---
drivers/pci/xen-pcifront.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 53df39a..d78d884 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -866,6 +866,11 @@ static int pcifront_try_connect(struct pcifront_device *pdev)
xenbus_dev_error(pdev->xdev, err,
"No PCI Roots found, trying 0000:00");
err = pcifront_scan_root(pdev, 0, 0);
+ if (err) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error scanning PCI root 0000:00");
+ goto out;
+ }
num_roots = 0;
} else if (err != 1) {
if (err == 0)
@@ -947,6 +952,11 @@ static int pcifront_attach_devices(struct pcifront_device *pdev)
xenbus_dev_error(pdev->xdev, err,
"No PCI Roots found, trying 0000:00");
err = pcifront_rescan_root(pdev, 0, 0);
+ if (err) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error scanning PCI root 0000:00");
+ goto out;
+ }
num_roots = 0;
} else if (err != 1) {
if (err == 0)

[Bjorn Helgaas]

Post by Chen Gang
When pcifront_rescan_root() or pcifront_scan_root() fails, need return
error code, neither set XenbusStateConnected state, just like the other
areas have done.
For pcifront_rescan_root(), it will return error code ("num_roots = 0;",
skip xenbus_switch_state return value).
For pcifront_scan_root(), it will return 0 ("num_roots = 0;", set 0 by
the return value of xenbus_switch_state, which always return 0, at
present).

The changelog is somewhat confusing because it talks about the patch hunks
in reverse order (the pcifront_scan_root() change is first in the patch,
but the changelog mentions pcifront_rescan_root() first). I *think* this
means:

When pcifront_try_connect() finds no PCI roots, it falls back to calling
pcifront_scan_root() for 0000:00. If that fails, it used to switch to
XenbusStateConnected and return success (because xenbus_switch_state()
currently always succeeds).

If pcifront_scan_root() fails, leave the XenbusState unchanged and
return an error code.

Similarly, pcifront_attach_devices() falls back to calling
pcifront_rescan_root() for 0000:00. If that fails, it used to
switch to XenbusStateConnected and return an error code.

If pcifront_rescan_root() fails, leave the XenbusState unchanged and
return the error code.

The "num_roots" part doesn't seem relevant to me.
Konrad, if you want to take this, feel free. Otherwise, if you ack it and
you think my changelog understanding makes sense, I can pick it up.

It does seem odd that pcifront_attach_devices() ignores the
xenbus_switch_state() return value while pcifront_try_connect() does not.
But many other callers also ignore the return value, so maybe that's OK.

Bjorn

Post by Chen Gang
---
drivers/pci/xen-pcifront.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 53df39a..d78d884 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -866,6 +866,11 @@ static int pcifront_try_connect(struct pcifront_device *pdev)
xenbus_dev_error(pdev->xdev, err,
"No PCI Roots found, trying 0000:00");
err = pcifront_scan_root(pdev, 0, 0);
+ if (err) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error scanning PCI root 0000:00");
+ goto out;
+ }
num_roots = 0;
} else if (err != 1) {
if (err == 0)
@@ -947,6 +952,11 @@ static int pcifront_attach_devices(struct pcifront_device *pdev)
xenbus_dev_error(pdev->xdev, err,
"No PCI Roots found, trying 0000:00");
err = pcifront_rescan_root(pdev, 0, 0);
+ if (err) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error scanning PCI root 0000:00");
+ goto out;
+ }
num_roots = 0;
} else if (err != 1) {
if (err == 0)
--
1.9.3