From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Tue, 29 Oct 2024 00:23:04 +0000 (+0100)
Subject: Revert "driver core: Fix uevent_show() vs driver detach race"
X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1cfc329304617838dc06f021bbbde3bc79cd655e;p=linux

Revert "driver core: Fix uevent_show() vs driver detach race"

commit 9a71892cbcdb9d1459c84f5a4c722b14354158a5 upstream.

This reverts commit 15fffc6a5624b13b428bb1c6e9088e32a55eb82c.

This commit causes a regression, so revert it for now until it can come
back in a way that works for everyone.

Link: https://lore.kernel.org/all/172790598832.1168608.4519484276671503678.stgit@dwillia2-xfh.jf.intel.com/
Fixes: 15fffc6a5624 ("driver core: Fix uevent_show() vs driver detach race")
Cc: stable <stable@kernel.org>
Cc: Ashish Sangwan <a.sangwan@samsung.com>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Dirk Behme <dirk.behme@de.bosch.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/base/core.c b/drivers/base/core.c
index b81fd39226ca..b13a60de5a86 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -25,7 +25,6 @@
 #include <linux/mutex.h>
 #include <linux/pm_runtime.h>
 #include <linux/netdevice.h>
-#include <linux/rcupdate.h>
 #include <linux/sched/signal.h>
 #include <linux/sched/mm.h>
 #include <linux/sysfs.h>
@@ -1910,7 +1909,6 @@ static int dev_uevent(struct kset *kset, struct kobject *kobj,
 		      struct kobj_uevent_env *env)
 {
 	struct device *dev = kobj_to_dev(kobj);
-	struct device_driver *driver;
 	int retval = 0;
 
 	/* add device node properties if present */
@@ -1939,12 +1937,8 @@ static int dev_uevent(struct kset *kset, struct kobject *kobj,
 	if (dev->type && dev->type->name)
 		add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
 
-	/* Synchronize with module_remove_driver() */
-	rcu_read_lock();
-	driver = READ_ONCE(dev->driver);
-	if (driver)
-		add_uevent_var(env, "DRIVER=%s", driver->name);
-	rcu_read_unlock();
+	if (dev->driver)
+		add_uevent_var(env, "DRIVER=%s", dev->driver->name);
 
 	/* Add common DT information about the device */
 	of_device_uevent(dev, env);
@@ -2014,8 +2008,11 @@ static ssize_t uevent_show(struct device *dev, struct device_attribute *attr,
 	if (!env)
 		return -ENOMEM;
 
+	/* Synchronize with really_probe() */
+	device_lock(dev);
 	/* let the kset specific function add its keys */
 	retval = kset->uevent_ops->uevent(kset, &dev->kobj, env);
+	device_unlock(dev);
 	if (retval)
 		goto out;
 
diff --git a/drivers/base/module.c b/drivers/base/module.c
index 851cc5367c04..46ad4d636731 100644
--- a/drivers/base/module.c
+++ b/drivers/base/module.c
@@ -7,7 +7,6 @@
 #include <linux/errno.h>
 #include <linux/slab.h>
 #include <linux/string.h>
-#include <linux/rcupdate.h>
 #include "base.h"
 
 static char *make_driver_name(struct device_driver *drv)
@@ -78,9 +77,6 @@ void module_remove_driver(struct device_driver *drv)
 	if (!drv)
 		return;
 
-	/* Synchronize with dev_uevent() */
-	synchronize_rcu();
-
 	sysfs_remove_link(&drv->p->kobj, "module");
 
 	if (drv->owner)