From 654888327e9f655a9d55ad477a9583e90e8c9b5c Mon Sep 17 00:00:00 2001
From: Lukas Wunner <lukas@wunner.de>
Date: Wed, 8 Jul 2020 15:27:01 +0200
Subject: [PATCH] driver core: Avoid binding drivers to dead devices
Git-commit: 654888327e9f655a9d55ad477a9583e90e8c9b5c
Patch-mainline: v5.9-rc1
References: git-fixes

Commit 3451a495ef24 ("driver core: Establish order of operations for
device_add and device_del via bitflag") sought to prevent asynchronous
driver binding to a device which is being removed.  It added a
per-device "dead" flag which is checked in the following code paths:

* asynchronous binding in __driver_attach_async_helper()
*  synchronous binding in device_driver_attach()
* asynchronous binding in __device_attach_async_helper()

It did *not* check the flag upon:

*  synchronous binding in __device_attach()

However __device_attach() may also be called asynchronously from:

deferred_probe_work_func()
  bus_probe_device()
    device_initial_probe()
      __device_attach()

So if the commit's intention was to check the "dead" flag in all
asynchronous code paths, then a check is also necessary in
__device_attach().  Add the missing check.

Fixes: 3451a495ef24 ("driver core: Establish order of operations for device_add and device_del via bitflag")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v5.1+
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Link: https://lore.kernel.org/r/de88a23a6fe0ef70f7cfd13c8aea9ab51b4edab6.1594214103.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/base/dd.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index fce8e35b6367..b29faa24eef8 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -864,7 +864,9 @@ static int __device_attach(struct device *dev, bool allow_async)
 	int ret = 0;
 
 	device_lock(dev);
-	if (dev->driver) {
+	if (dev->p->dead) {
+		goto out_unlock;
+	} else if (dev->driver) {
 		if (device_is_bound(dev)) {
 			ret = 1;
 			goto out_unlock;
-- 
2.16.4