This is a note to let you know that I've just added the patch titled arm/xen: Don't probe xenbus as part of an early initcall to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: arm-xen-don-t-probe-xenbus-as-part-of-an-early-initcall.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From c4295ab0b485b8bc50d2264bcae2acd06f25caaf Mon Sep 17 00:00:00 2001 From: Julien Grall <jgrall@xxxxxxxxxx> Date: Wed, 10 Feb 2021 17:06:54 +0000 Subject: arm/xen: Don't probe xenbus as part of an early initcall From: Julien Grall <jgrall@xxxxxxxxxx> 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@xxxxxxxxxxxxxxx Fixes: 3499ba8198cad ("xen: Fix event channel callback via INTX/GSI") Reported-by: Ian Jackson <iwj@xxxxxxxxxxxxxx> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx> Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210210170654.5377-1-julien@xxxxxxx Signed-off-by: Juergen Gross <jgross@xxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -404,8 +404,6 @@ 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 @@ -187,8 +187,6 @@ 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); \ Patches currently in stable-queue which might be from jgrall@xxxxxxxxxx are queue-4.19/arm-xen-don-t-probe-xenbus-as-part-of-an-early-initcall.patch