xen: pcifront: Process failure for pcifront_(re)scan_root()

PATCH Applied Chen Gang 2 participants 5 messages Oct 6, 2014 – Nov 6, 2014

Subsystems (3)

PCI Xen hypervisor interface Xen PCI

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Chen Gang

author

2014-10-06 02:58 UTC #0 lore raw

PATCH 1/1 xen: pcifront: Process failure for pcifront_(re)scan_root()

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 <[email protected]>

---
 drivers/pci/xen-pcifront.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

drivers/pci/xen-pcifront.c +10 -0

index 53df39a..d78d884 100644
@@ -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)

Signature · 1 line

1.9.3

Bjorn Helgaas

maintainer

2014-10-15 00:09 UTC #1 lore raw

Quoted 10 lines · 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.

Quoted 1 line

Signed-off-by Chen Gang <[email protected]>

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

Quoted 34 lines

---
 drivers/pci/xen-pcifront.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

drivers/pci/xen-pcifront.c +10 -0

index 53df39a..d78d884 100644
@@ -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)

Signature · 1 line

1.9.3

Bjorn Helgaas

maintainer

2014-10-15 00:09 UTC #2 lore raw

In reply to Chen Gang

Quoted 10 lines · 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).

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.

Quoted 1 line

Signed-off-by Chen Gang <[email protected]>

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.

Bjorn

Quoted 34 lines

---
 drivers/pci/xen-pcifront.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

drivers/pci/xen-pcifront.c +10 -0

index 53df39a..d78d884 100644
@@ -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)

Signature · 1 line

1.9.3

Bjorn Helgaas

maintainer Applied

2014-11-06 04:16 UTC #3 lore raw

In reply to Chen Gang

Quoted 4 lines · 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.

Quoted 8 lines

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 <[email protected]>

Applied to pci/virtualization for v3.19, with Konrad's ack and my changelog rework. Thanks!

Quoted 34 lines

---
 drivers/pci/xen-pcifront.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

drivers/pci/xen-pcifront.c +10 -0

index 53df39a..d78d884 100644
@@ -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)

Signature · 1 line

1.9.3

Bjorn Helgaas

maintainer Applied

2014-11-06 04:16 UTC #4 lore raw

In reply to Chen Gang

Quoted 4 lines · 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.

Quoted 8 lines

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 <[email protected]>

Applied to pci/virtualization for v3.19, with Konrad's ack and my changelog rework. Thanks!

Quoted 34 lines

---
 drivers/pci/xen-pcifront.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

drivers/pci/xen-pcifront.c +10 -0

index 53df39a..d78d884 100644
@@ -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)

Signature · 1 line

1.9.3