[PATCH 5.10 009/104] arm/xen: Dont probe xenbus as part of an early initcall

Greg Kroah-Hartman
2021-02-15T15:38:56Z

From: Julien Grall <jgrall@amazon.com>

commit c4295ab0b485b8bc50d2264bcae2acd06f25caaf upstream.

After Commit 3499ba8198cad ("xen: Fix event channel callback via
INTX/GSI"), xenbus_probe() will be called too early on Arm. This will
recent to a guest hang during boot.

If the hang wasn't there, we would have ended up to call
xenbus_probe() twice (the second time is in xenbus_probe_initcall()).

We don't need to initialize xenbus_probe() early for Arm guest.
Therefore, the call in xen_guest_init() is now removed.

After this change, there is no more external caller for xenbus_probe().
So the function is turned to a static one. Interestingly there were two
prototypes for it.

Cc: stable@vger.kernel.org
Fixes: 3499ba8198cad ("xen: Fix event channel callback via INTX/GSI")
Reported-by: Ian Jackson <iwj@xenproject.org>
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20210210170654.5377-1-julien@xen.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm/xen/enlighten.c | 2 --
drivers/xen/xenbus/xenbus.h | 1 -
drivers/xen/xenbus/xenbus_probe.c | 2 +-
include/xen/xenbus.h | 2 --
4 files changed, 1 insertion(+), 6 deletions(-)

--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -370,8 +370,6 @@ static int __init xen_guest_init(void)
return -ENOMEM;
}
gnttab_init();
- if (!xen_initial_domain())
- xenbus_probe();

/*
* Making sure board specific code will not set up ops for
--- a/drivers/xen/xenbus/xenbus.h
+++ b/drivers/xen/xenbus/xenbus.h
@@ -115,7 +115,6 @@ int xenbus_probe_node(struct xen_bus_typ
const char *type,
const char *nodename);
int xenbus_probe_devices(struct xen_bus_type *bus);
-void xenbus_probe(void);

void xenbus_dev_changed(const char *node, struct xen_bus_type *bus);

--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -683,7 +683,7 @@ void unregister_xenstore_notifier(struct
}
EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);

-void xenbus_probe(void)
+static void xenbus_probe(void)
{
xenstored_ready = 1;

--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -192,8 +192,6 @@ void xs_suspend_cancel(void);

struct work_struct;

-void xenbus_probe(void);
-
#define XENBUS_IS_ERR_READ(str) ({ \
if (!IS_ERR(str) && strlen(str) == 0) { \
kfree(str); \