diff mbox series

[2/2] 9p/xen: fix connection sequence

Message ID 20230130113036.7087-3-jgross@suse.com (mailing list archive)
State Not Applicable
Delegated to: Netdev Maintainers
Headers show
Series 9p/xen: fix 2 issues with connecting to backend | expand

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Context Check Description
netdev/tree_selection success Guessed tree name to be net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix warning Target tree name not specified in the subject
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers fail 2 blamed authors not CCed: sstabellini@kernel.org boris.ostrovsky@oracle.com; 2 maintainers not CCed: sstabellini@kernel.org boris.ostrovsky@oracle.com
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 75 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Jürgen Groß Jan. 30, 2023, 11:30 a.m. UTC 
Today the connection sequence of the Xen 9pfs frontend doesn't match
the documented sequence. It can work reliably only for a PV 9pfs device
having been added at boot time already, as the frontend is not waiting
for the backend to have set its state to "XenbusStateInitWait" before
reading the backend properties from Xenstore.

Fix that by following the documented sequence [1] (the documentation
has a bug, so the reference is for the patch fixing that).

[1]: https://lore.kernel.org/xen-devel/20230130090937.31623-1-jgross@suse.com/T/#u

Fixes: 868eb122739a ("xen/9pfs: introduce Xen 9pfs transport driver")
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 net/9p/trans_xen.c | 38 +++++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 15 deletions(-)

Comments

Simon Horman Jan. 31, 2023, 6:48 p.m. UTC | #1 
On Mon, Jan 30, 2023 at 12:30:36PM +0100, Juergen Gross wrote:
> Today the connection sequence of the Xen 9pfs frontend doesn't match
> the documented sequence. It can work reliably only for a PV 9pfs device
> having been added at boot time already, as the frontend is not waiting
> for the backend to have set its state to "XenbusStateInitWait" before
> reading the backend properties from Xenstore.
> 
> Fix that by following the documented sequence [1] (the documentation
> has a bug, so the reference is for the patch fixing that).
> 
> [1]: https://lore.kernel.org/xen-devel/20230130090937.31623-1-jgross@suse.com/T/#u
> 
> Fixes: 868eb122739a ("xen/9pfs: introduce Xen 9pfs transport driver")
> Signed-off-by: Juergen Gross <jgross@suse.com>

It's unclear if this series is targeted at 'net' or 'net-next'.
FWIIW, I feel I feel it would be more appropriate for the latter
as these do not feel like bug fixes: feel free to differ on that.

Regardless,

Reviewed-by: Simon Horman <simon.horman@corigine.com>
diff mbox series

Patch

diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index ad2947a3b376..c64050e839ac 100644
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -372,12 +372,11 @@  static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
 	return ret;
 }
 
-static int xen_9pfs_front_probe(struct xenbus_device *dev,
-				const struct xenbus_device_id *id)
+static int xen_9pfs_front_init(struct xenbus_device *dev)
 {
 	int ret, i;
 	struct xenbus_transaction xbt;
-	struct xen_9pfs_front_priv *priv = NULL;
+	struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
 	char *versions, *v;
 	unsigned int max_rings, max_ring_order, len = 0;
 
@@ -405,11 +404,6 @@  static int xen_9pfs_front_probe(struct xenbus_device *dev,
 	if (p9_xen_trans.maxsize > XEN_FLEX_RING_SIZE(max_ring_order))
 		p9_xen_trans.maxsize = XEN_FLEX_RING_SIZE(max_ring_order) / 2;
 
-	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
-	if (!priv)
-		return -ENOMEM;
-
-	priv->dev = dev;
 	priv->num_rings = XEN_9PFS_NUM_RINGS;
 	priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings),
 			      GFP_KERNEL);
@@ -468,23 +462,35 @@  static int xen_9pfs_front_probe(struct xenbus_device *dev,
 		goto error;
 	}
 
-	write_lock(&xen_9pfs_lock);
-	list_add_tail(&priv->list, &xen_9pfs_devs);
-	write_unlock(&xen_9pfs_lock);
-	dev_set_drvdata(&dev->dev, priv);
-	xenbus_switch_state(dev, XenbusStateInitialised);
-
 	return 0;
 
  error_xenbus:
 	xenbus_transaction_end(xbt, 1);
 	xenbus_dev_fatal(dev, ret, "writing xenstore");
  error:
-	dev_set_drvdata(&dev->dev, NULL);
 	xen_9pfs_front_free(priv);
 	return ret;
 }
 
+static int xen_9pfs_front_probe(struct xenbus_device *dev,
+				const struct xenbus_device_id *id)
+{
+	struct xen_9pfs_front_priv *priv = NULL;
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->dev = dev;
+	dev_set_drvdata(&dev->dev, priv);
+
+	write_lock(&xen_9pfs_lock);
+	list_add_tail(&priv->list, &xen_9pfs_devs);
+	write_unlock(&xen_9pfs_lock);
+
+	return 0;
+}
+
 static int xen_9pfs_front_resume(struct xenbus_device *dev)
 {
 	dev_warn(&dev->dev, "suspend/resume unsupported\n");
@@ -503,6 +509,8 @@  static void xen_9pfs_front_changed(struct xenbus_device *dev,
 		break;
 
 	case XenbusStateInitWait:
+		if (!xen_9pfs_front_init(dev))
+			xenbus_switch_state(dev, XenbusStateInitialised);
 		break;
 
 	case XenbusStateConnected: