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* [PATCH v2 1/2] driver: xen-blkfront: move talk_to_blkback to a more suitable place
@ 2015-05-20 13:10 Bob Liu
  2015-05-20 13:10 ` [PATCH v4 2/2] xen/block: add multi-page ring support Bob Liu
  2015-05-21 10:52 ` [PATCH v2 1/2] driver: xen-blkfront: move talk_to_blkback to a more suitable place Roger Pau Monné
  0 siblings, 2 replies; 11+ messages in thread
From: Bob Liu @ 2015-05-20 13:10 UTC (permalink / raw)
  To: xen-devel
  Cc: david.vrabel, justing, konrad.wilk, roger.pau, paul.durrant,
	linux-kernel, Bob Liu

The major responsibility of talk_to_blkback() is allocate and initialize the
request ring and writes the ring info stuff out.
But this work should be done after backend entered 'XenbusStateInitWait' as
defined in the protocol file.
See xen/include/public/io/blkif.h in XEN git tree:
Front                                Back
=================================    =====================================
XenbusStateInitialising              XenbusStateInitialising
 o Query virtual device               o Query backend device identification
   properties.                          data.
 o Setup OS device instance.          o Open and validate backend device.
                                      o Publish backend features and
                                        transport parameters.
                                                     |
                                                     |
                                                     V
                                     XenbusStateInitWait

o Query backend features and
  transport parameters.
o Allocate and initialize the
  request ring.

There is no problem with this yet, but it is an violation of the design and
furthermore it would not allow frontend/backend to negotiate 'multi-page' and
'multi-queue' features.

Changes in v2:
 - Re-write the commit message to be more clear.

Signed-off-by: Bob Liu <bob.liu@oracle.com>
---
 drivers/block/xen-blkfront.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 2c61cf8..88e23fd 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1430,13 +1430,6 @@ static int blkfront_probe(struct xenbus_device *dev,
 	info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
 	dev_set_drvdata(&dev->dev, info);
 
-	err = talk_to_blkback(dev, info);
-	if (err) {
-		kfree(info);
-		dev_set_drvdata(&dev->dev, NULL);
-		return err;
-	}
-
 	return 0;
 }
 
@@ -1906,8 +1899,13 @@ static void blkback_changed(struct xenbus_device *dev,
 	dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
 
 	switch (backend_state) {
-	case XenbusStateInitialising:
 	case XenbusStateInitWait:
+		if (talk_to_blkback(dev, info)) {
+			kfree(info);
+			dev_set_drvdata(&dev->dev, NULL);
+			break;
+		}
+	case XenbusStateInitialising:
 	case XenbusStateInitialised:
 	case XenbusStateReconfiguring:
 	case XenbusStateReconfigured:
-- 
1.8.3.1


^ permalink raw reply related	[flat|nested] 11+ messages in thread
* [PATCH v2 1/2] driver: xen-blkfront: move talk_to_blkback to a more suitable place
@ 2015-05-21 23:59 Bob Liu
  0 siblings, 0 replies; 11+ messages in thread
From: Bob Liu @ 2015-05-21 23:59 UTC (permalink / raw)
  To: xen-devel
  Cc: david.vrabel, justing, konrad.wilk, roger.pau, paul.durrant,
	julien.grall, boris.ostrovsky, linux-kernel, Bob Liu

The major responsibility of talk_to_blkback() is allocate and initialize
the request ring and write the ring info to xenstore.
But this work should be done after backend entered 'XenbusStateInitWait' as
defined in the protocol file.
See xen/include/public/io/blkif.h in XEN git tree:
Front                                Back
=================================    =====================================
XenbusStateInitialising              XenbusStateInitialising
 o Query virtual device               o Query backend device identification
   properties.                          data.
 o Setup OS device instance.          o Open and validate backend device.
                                      o Publish backend features and
                                        transport parameters.
                                                     |
                                                     |
                                                     V
                                     XenbusStateInitWait

o Query backend features and
  transport parameters.
o Allocate and initialize the
  request ring.

There is no problem with this yet, but it is an violation of the design and
furthermore it would not allow frontend/backend to negotiate 'multi-page'
and 'multi-queue' features.

Changes in v2:
 - Re-write the commit message to be more clear.

Signed-off-by: Bob Liu <bob.liu@oracle.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
---
 drivers/block/xen-blkfront.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 2c61cf8..88e23fd 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1430,13 +1430,6 @@ static int blkfront_probe(struct xenbus_device *dev,
 	info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
 	dev_set_drvdata(&dev->dev, info);
 
-	err = talk_to_blkback(dev, info);
-	if (err) {
-		kfree(info);
-		dev_set_drvdata(&dev->dev, NULL);
-		return err;
-	}
-
 	return 0;
 }
 
@@ -1906,8 +1899,13 @@ static void blkback_changed(struct xenbus_device *dev,
 	dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
 
 	switch (backend_state) {
-	case XenbusStateInitialising:
 	case XenbusStateInitWait:
+		if (talk_to_blkback(dev, info)) {
+			kfree(info);
+			dev_set_drvdata(&dev->dev, NULL);
+			break;
+		}
+	case XenbusStateInitialising:
 	case XenbusStateInitialised:
 	case XenbusStateReconfiguring:
 	case XenbusStateReconfigured:
-- 
1.8.3.1


^ permalink raw reply related	[flat|nested] 11+ messages in thread
end of thread, other threads:[~2015-05-22  0:00 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2015-05-20 13:10 [PATCH v2 1/2] driver: xen-blkfront: move talk_to_blkback to a more suitable place Bob Liu
2015-05-20 13:10 ` [PATCH v4 2/2] xen/block: add multi-page ring support Bob Liu
2015-05-20 13:21   ` [Xen-devel] " Julien Grall
2015-05-20 14:56     ` Roger Pau Monné
2015-05-20 15:00       ` Julien Grall
2015-05-20 23:47         ` Bob Liu
2015-05-21 11:22   ` Roger Pau Monné
2015-05-21 13:03     ` Bob Liu
2015-05-21 13:33       ` Roger Pau Monné
2015-05-21 10:52 ` [PATCH v2 1/2] driver: xen-blkfront: move talk_to_blkback to a more suitable place Roger Pau Monné
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2015-05-21 23:59 Bob Liu

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