Re: [Xen-devel] [PATCH] xen/xenbus: Use 'void' instead of 'int' for the return of xenbus_switch_state()

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On 09/26/2014 06:36 PM, Chen Gang wrote:

When xenbus_switch_state() fails, it will call xenbus_switch_fatal()
internally, so need not return any status value, then use 'void' instead
of 'int' for xenbus_switch_state() and __xenbus_switch_state().

Also need be sure that all callers which check the return value must let
'err' be 0.

And also need change the related comments for xenbus_switch_state().

Signed-off-by: Chen Gang <gang.chen.5i5j@xxxxxxxxx>


Acked-by: Juergen Gross <jgross@xxxxxxxx>


---
  drivers/block/xen-blkback/xenbus.c |  9 ++-------
  drivers/net/xen-netback/xenbus.c   |  5 +----
  drivers/pci/xen-pcifront.c         | 15 ++++++---------
  drivers/xen/xen-pciback/xenbus.c   | 21 ++++-----------------
  drivers/xen/xen-scsiback.c         |  5 +----
  drivers/xen/xenbus/xenbus_client.c | 16 ++++++++--------
  include/xen/xenbus.h               |  3 ++-
  7 files changed, 24 insertions(+), 50 deletions(-)

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 3a8b810..fdcc584 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -587,9 +587,7 @@ static int xen_blkbk_probe(struct xenbus_device *dev,
  	if (err)
  		goto fail;

-	err = xenbus_switch_state(dev, XenbusStateInitWait);
-	if (err)
-		goto fail;
+	xenbus_switch_state(dev, XenbusStateInitWait);

  	return 0;

@@ -837,10 +835,7 @@ again:
  	if (err)
  		xenbus_dev_fatal(dev, err, "ending transaction");

-	err = xenbus_switch_state(dev, XenbusStateConnected);
-	if (err)
-		xenbus_dev_fatal(dev, err, "%s: switching to Connected state",
-				 dev->nodename);
+	xenbus_switch_state(dev, XenbusStateConnected);

  	return;
   abort:
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 9c47b89..b5c3d47 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -337,10 +337,7 @@ static int netback_probe(struct xenbus_device *dev,
  	if (err)
  		pr_debug("Error writing multi-queue-max-queues\n");

-	err = xenbus_switch_state(dev, XenbusStateInitWait);
-	if (err)
-		goto fail;
-
+	xenbus_switch_state(dev, XenbusStateInitWait);
  	be->state = XenbusStateInitWait;

  	/* This kicks hotplug scripts, so do it immediately. */
diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 53df39a..c1d73b7 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -901,18 +901,16 @@ static int pcifront_try_connect(struct pcifront_device *pdev)
  		}
  	}

-	err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
-
+	xenbus_switch_state(pdev->xdev, XenbusStateConnected);
+	return 0;
  out:
  	return err;
  }

  static int pcifront_try_disconnect(struct pcifront_device *pdev)
  {
-	int err = 0;
  	enum xenbus_state prev_state;

-
  	prev_state = xenbus_read_driver_state(pdev->xdev->nodename);

  	if (prev_state >= XenbusStateClosing)
@@ -923,11 +921,10 @@ static int pcifront_try_disconnect(struct pcifront_device *pdev)
  		pcifront_disconnect(pdev);
  	}

-	err = xenbus_switch_state(pdev->xdev, XenbusStateClosed);
+	xenbus_switch_state(pdev->xdev, XenbusStateClosed);

  out:
-
-	return err;
+	return 0;
  }

  static int pcifront_attach_devices(struct pcifront_device *pdev)
@@ -1060,8 +1057,8 @@ static int pcifront_detach_devices(struct pcifront_device *pdev)
  			domain, bus, slot, func);
  	}

-	err = xenbus_switch_state(pdev->xdev, XenbusStateReconfiguring);
-
+	xenbus_switch_state(pdev->xdev, XenbusStateReconfiguring);
+	return 0;
  out:
  	return err;
  }
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index c214daa..630a215 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -184,10 +184,7 @@ static int xen_pcibk_attach(struct xen_pcibk_device *pdev)

  	dev_dbg(&pdev->xdev->dev, "Connecting...\n");

-	err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
-	if (err)
-		xenbus_dev_fatal(pdev->xdev, err,
-				 "Error switching to connected state!");
+	xenbus_switch_state(pdev->xdev, XenbusStateConnected);

  	dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);
  out:
@@ -500,12 +497,7 @@ static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev)
  		}
  	}

-	err = xenbus_switch_state(pdev->xdev, XenbusStateReconfigured);
-	if (err) {
-		xenbus_dev_fatal(pdev->xdev, err,
-				 "Error switching to reconfigured state!");
-		goto out;
-	}
+	xenbus_switch_state(pdev->xdev, XenbusStateReconfigured);

  out:
  	mutex_unlock(&pdev->dev_lock);
@@ -640,10 +632,7 @@ static int xen_pcibk_setup_backend(struct xen_pcibk_device *pdev)
  		goto out;
  	}

-	err = xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
-	if (err)
-		xenbus_dev_fatal(pdev->xdev, err,
-				 "Error switching to initialised state!");
+	xenbus_switch_state(pdev->xdev, XenbusStateInitialised);

  out:
  	mutex_unlock(&pdev->dev_lock);
@@ -683,9 +672,7 @@ static int xen_pcibk_xenbus_probe(struct xenbus_device *dev,
  	}

  	/* wait for xend to configure us */
-	err = xenbus_switch_state(dev, XenbusStateInitWait);
-	if (err)
-		goto out;
+	xenbus_switch_state(dev, XenbusStateInitWait);

  	/* watch the backend node for backend configuration information */
  	err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
index ad11258..847bc9c 100644
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -1225,10 +1225,7 @@ static int scsiback_probe(struct xenbus_device *dev,
  	if (err)
  		xenbus_dev_error(dev, err, "writing feature-sg-grant");

-	err = xenbus_switch_state(dev, XenbusStateInitWait);
-	if (err)
-		goto fail;
-
+	xenbus_switch_state(dev, XenbusStateInitWait);
  	return 0;

  fail:
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index ca74410..e2bcd1d 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -166,7 +166,7 @@ EXPORT_SYMBOL_GPL(xenbus_watch_pathfmt);
  static void xenbus_switch_fatal(struct xenbus_device *, int, int,
  				const char *, ...);

-static int
+static void
  __xenbus_switch_state(struct xenbus_device *dev,
  		      enum xenbus_state state, int depth)
  {
@@ -188,7 +188,7 @@ __xenbus_switch_state(struct xenbus_device *dev,
  	int err, abort;

  	if (state == dev->state)
-		return 0;
+		return;

  again:
  	abort = 1;
@@ -196,7 +196,7 @@ again:
  	err = xenbus_transaction_start(&xbt);
  	if (err) {
  		xenbus_switch_fatal(dev, depth, err, "starting transaction");
-		return 0;
+		return;
  	}

  	err = xenbus_scanf(xbt, dev->nodename, "state", "%d", &current_state);
@@ -219,7 +219,7 @@ abort:
  	} else
  		dev->state = state;

-	return 0;
+	return;
  }

  /**
@@ -228,12 +228,12 @@ abort:
   * @state: new state
   *
   * Advertise in the store a change of the given driver to the given new_state.
- * Return 0 on success, or -errno on error.  On error, the device will switch
- * to XenbusStateClosing, and the error will be saved in the store.
+ * When failure occurs, it will call xenbus_switch_fatal() internally, so need
+ * not return value to notify upper caller.
   */
-int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
+void xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
  {
-	return __xenbus_switch_state(dev, state, 0);
+	__xenbus_switch_state(dev, state, 0);
  }

  EXPORT_SYMBOL_GPL(xenbus_switch_state);
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index 0324c6d..587c53d 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -195,7 +195,8 @@ int xenbus_watch_pathfmt(struct xenbus_device *dev, struct xenbus_watch *watch,
  					  const char **, unsigned int),
  			 const char *pathfmt, ...);

-int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state new_state);
+void xenbus_switch_state(struct xenbus_device *dev,
+			 enum xenbus_state new_state);
  int xenbus_grant_ring(struct xenbus_device *dev, unsigned long ring_mfn);
  int xenbus_map_ring_valloc(struct xenbus_device *dev,
  			   int gnt_ref, void **vaddr);



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