[PATCH v2 1/2] driver: xen-blkfront: move talk_to_blkback to a more suitable place

From: Bob Liu
Date: Thu May 21 2015 - 20:00:22 EST


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@xxxxxxxxxx>
Acked-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
---
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

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