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

From: Juergen Gross
Date: Mon Sep 29 2014 - 01:09:50 EST

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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