[PATCH 2/5] xen/xenbus: Add 'will_handle' callback support in xenbus_watch_path()

From: SeongJae Park
Date: Tue Jan 05 2021 - 06:03:26 EST


From: SeongJae Park <sjpark@xxxxxxxxx>

Some code does not directly make 'xenbus_watch' object and call
'register_xenbus_watch()' but use 'xenbus_watch_path()' instead. This
commit adds support of 'will_handle' callback in the
'xenbus_watch_path()' and it's wrapper, 'xenbus_watch_pathfmt()'.

This is part of XSA-349

This is upstream commit 2e85d32b1c865bec703ce0c962221a5e955c52c2

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: SeongJae Park <sjpark@xxxxxxxxx>
Reported-by: Michael Kurth <mku@xxxxxxxxx>
Reported-by: Pawel Wieczorkiewicz <wipawel@xxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
drivers/block/xen-blkback/xenbus.c | 3 ++-
drivers/net/xen-netback/xenbus.c | 2 +-
drivers/xen/xen-pciback/xenbus.c | 2 +-
drivers/xen/xenbus/xenbus_client.c | 9 +++++++--
drivers/xen/xenbus/xenbus_probe.c | 2 +-
include/xen/xenbus.h | 6 +++++-
6 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 9a4ac6fd262a..27c9d7a5b4de 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -646,7 +646,8 @@ static int xen_blkbk_probe(struct xenbus_device *dev,
/* setup back pointer */
be->blkif->be = be;

- err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
+ err = xenbus_watch_pathfmt(dev, &be->backend_watch, NULL,
+ backend_changed,
"%s/%s", dev->nodename, "physical-device");
if (err)
goto fail;
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 5cb9dbf62816..78788402edd8 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -1040,7 +1040,7 @@ static void connect(struct backend_info *be)
xenvif_carrier_on(be->vif);

unregister_hotplug_status_watch(be);
- err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
+ err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch, NULL,
hotplug_status_changed,
"%s/%s", dev->nodename, "hotplug-status");
if (!err)
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index f33eb40cb414..36ec99cff507 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -689,7 +689,7 @@ static int xen_pcibk_xenbus_probe(struct xenbus_device *dev,

/* watch the backend node for backend configuration information */
err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
- xen_pcibk_be_watch);
+ NULL, xen_pcibk_be_watch);
if (err)
goto out;

diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index d02d25f784c9..8bbd887ca422 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -114,19 +114,22 @@ EXPORT_SYMBOL_GPL(xenbus_strstate);
*/
int xenbus_watch_path(struct xenbus_device *dev, const char *path,
struct xenbus_watch *watch,
+ bool (*will_handle)(struct xenbus_watch *,
+ const char **, unsigned int),
void (*callback)(struct xenbus_watch *,
const char **, unsigned int))
{
int err;

watch->node = path;
- watch->will_handle = NULL;
+ watch->will_handle = will_handle;
watch->callback = callback;

err = register_xenbus_watch(watch);

if (err) {
watch->node = NULL;
+ watch->will_handle = NULL;
watch->callback = NULL;
xenbus_dev_fatal(dev, err, "adding watch on %s", path);
}
@@ -153,6 +156,8 @@ EXPORT_SYMBOL_GPL(xenbus_watch_path);
*/
int xenbus_watch_pathfmt(struct xenbus_device *dev,
struct xenbus_watch *watch,
+ bool (*will_handle)(struct xenbus_watch *,
+ const char **, unsigned int),
void (*callback)(struct xenbus_watch *,
const char **, unsigned int),
const char *pathfmt, ...)
@@ -169,7 +174,7 @@ int xenbus_watch_pathfmt(struct xenbus_device *dev,
xenbus_dev_fatal(dev, -ENOMEM, "allocating path for watch");
return -ENOMEM;
}
- err = xenbus_watch_path(dev, path, watch, callback);
+ err = xenbus_watch_path(dev, path, watch, will_handle, callback);

if (err)
kfree(path);
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index c2d447687e33..c560c1b8489a 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -137,7 +137,7 @@ static int watch_otherend(struct xenbus_device *dev)
container_of(dev->dev.bus, struct xen_bus_type, bus);

return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
- bus->otherend_changed,
+ NULL, bus->otherend_changed,
"%s/%s", dev->otherend, "state");
}

diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index 11697aa023b5..1772507dc2c9 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -201,10 +201,14 @@ void xenbus_suspend_cancel(void);

int xenbus_watch_path(struct xenbus_device *dev, const char *path,
struct xenbus_watch *watch,
+ bool (*will_handle)(struct xenbus_watch *,
+ const char **, unsigned int),
void (*callback)(struct xenbus_watch *,
const char **, unsigned int));
-__printf(4, 5)
+__printf(5, 6)
int xenbus_watch_pathfmt(struct xenbus_device *dev, struct xenbus_watch *watch,
+ bool (*will_handle)(struct xenbus_watch *,
+ const char **, unsigned int),
void (*callback)(struct xenbus_watch *,
const char **, unsigned int),
const char *pathfmt, ...);
--
2.17.1