From 3fc21924100b13f73c734d0ce8dfcfe913fcf7a8 Mon Sep 17 00:00:00 2001
From: Dan Williams <dan.j.williams@intel.com>
Date: Fri, 24 Feb 2017 14:55:48 -0800
Subject: mm: validate device_hotplug is held for memory hotplug

mem_hotplug_begin() assumes that it can set mem_hotplug.active_writer
and run the hotplug process without racing another thread.  Validate
this assumption with a lockdep assertion.

Link: http://lkml.kernel.org/r/148693886229.16345.1770484669403334689.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 drivers/base/core.c | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'drivers/base/core.c')

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 8c25e68e67d7..3050e6f99403 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -638,6 +638,11 @@ int lock_device_hotplug_sysfs(void)
 	return restart_syscall();
 }
 
+void assert_held_device_hotplug(void)
+{
+	lockdep_assert_held(&device_hotplug_lock);
+}
+
 #ifdef CONFIG_BLOCK
 static inline int device_is_not_partition(struct device *dev)
 {
-- 
cgit v1.2.3