The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2e85d32b1c865bec703ce0c962221a5e955c52c2 Mon Sep 17 00:00:00 2001

From: SeongJae Park sjpark@amazon.de Date: Mon, 14 Dec 2020 10:04:18 +0100 Subject: [PATCH] xen/xenbus: Add 'will_handle' callback support in xenbus_watch_path()

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

Cc: stable@vger.kernel.org Signed-off-by: SeongJae Park sjpark@amazon.de Reported-by: Michael Kurth mku@amazon.de Reported-by: Pawel Wieczorkiewicz wipawel@amazon.de Reviewed-by: Juergen Gross jgross@suse.com Signed-off-by: Juergen Gross jgross@suse.com

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index 76912c584a76..1d8b8d24496c 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -675,7 +675,8 @@ 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 00f6f8dc56c8..6f10e0998f1c 100644 --- a/drivers/net/xen-netback/xenbus.c +++ b/drivers/net/xen-netback/xenbus.c @@ -824,7 +824,7 @@ 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 4b99ec3dec58..e7c692cfb2cf 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 0a21a12d9c34..0cd728961fce 100644 --- a/drivers/xen/xenbus/xenbus_client.c +++ b/drivers/xen/xenbus/xenbus_client.c @@ -127,19 +127,22 @@ 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 *, const char *), void (*callback)(struct xenbus_watch *, const char *, const char *)) { 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); } @@ -166,6 +169,8 @@ 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 *, const char *), void (*callback)(struct xenbus_watch *, const char *, const char *), const char *pathfmt, ...) @@ -182,7 +187,7 @@ 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 38725d97d909..4c3d1b84aa0a 100644 --- a/drivers/xen/xenbus/xenbus_probe.c +++ b/drivers/xen/xenbus/xenbus_probe.c @@ -136,7 +136,7 @@ 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 baa88bf0b9bc..c8574d1b814c 100644 --- a/include/xen/xenbus.h +++ b/include/xen/xenbus.h @@ -204,10 +204,14 @@ void xenbus_probe(struct work_struct *);

int xenbus_watch_path(struct xenbus_device *dev, const char *path, struct xenbus_watch *watch, + bool (*will_handle)(struct xenbus_watch *, + const char *, const char *), void (*callback)(struct xenbus_watch *, const char *, const char *)); -__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 *, const char *), void (*callback)(struct xenbus_watch *, const char *, const char *), const char *pathfmt, ...);