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From: Tejun Heo <tj@kernel.org>
To: lizefan@huawei.com, hannes@cmpxchg.org
Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
	kernel-team@fb.com, Fengguang Wu <fengguang.wu@intel.com>
Subject: [PATCH 9/8] cgroup: fix RCU related sparse warnings
Date: Thu, 22 Dec 2016 12:29:00 -0500	[thread overview]
Message-ID: <20161222172900.GD31216@htj.duckdns.org> (raw)
In-Reply-To: <20161220210827.11176-1-tj@kernel.org>

>From 9ca76e7e3cb885bc5701e9b1fe90c44f4aef123a Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Thu, 22 Dec 2016 12:28:01 -0500

kn->priv which is a void * is used as a RCU pointer by cgroup.  When
dereferencing it, it was passing kn->priv to rcu_derefreence() without
casting it into a RCU pointer triggering address space mismatch
warning from sparse.  Fix them.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
---
 kernel/cgroup/cgroup-v1.c | 2 +-
 kernel/cgroup/cgroup.c    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 37be09e..465b101 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -694,7 +694,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
 	 * @kn->priv is RCU safe.  Let's do the RCU dancing.
 	 */
 	rcu_read_lock();
-	cgrp = rcu_dereference(kn->priv);
+	cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
 	if (!cgrp || cgroup_is_dead(cgrp)) {
 		rcu_read_unlock();
 		mutex_unlock(&cgroup_mutex);
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index b6b9068..d9d82e9 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4932,7 +4932,7 @@ struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
 	 * have been or be removed at any point.  @kn->priv is RCU
 	 * protected for this access.  See css_release_work_fn() for details.
 	 */
-	cgrp = rcu_dereference(kn->priv);
+	cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
 	if (cgrp)
 		css = cgroup_css(cgrp, ss);
 
-- 
2.9.3

WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org,
	hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	kernel-team-b10kYP2dOMg@public.gmane.org,
	Fengguang Wu
	<fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Subject: [PATCH 9/8] cgroup: fix RCU related sparse warnings
Date: Thu, 22 Dec 2016 12:29:00 -0500	[thread overview]
Message-ID: <20161222172900.GD31216@htj.duckdns.org> (raw)
In-Reply-To: <20161220210827.11176-1-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>

From 9ca76e7e3cb885bc5701e9b1fe90c44f4aef123a Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Date: Thu, 22 Dec 2016 12:28:01 -0500

kn->priv which is a void * is used as a RCU pointer by cgroup.  When
dereferencing it, it was passing kn->priv to rcu_derefreence() without
casting it into a RCU pointer triggering address space mismatch
warning from sparse.  Fix them.

Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Reported-by: Fengguang Wu <fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 kernel/cgroup/cgroup-v1.c | 2 +-
 kernel/cgroup/cgroup.c    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 37be09e..465b101 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -694,7 +694,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
 	 * @kn->priv is RCU safe.  Let's do the RCU dancing.
 	 */
 	rcu_read_lock();
-	cgrp = rcu_dereference(kn->priv);
+	cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
 	if (!cgrp || cgroup_is_dead(cgrp)) {
 		rcu_read_unlock();
 		mutex_unlock(&cgroup_mutex);
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index b6b9068..d9d82e9 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4932,7 +4932,7 @@ struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
 	 * have been or be removed at any point.  @kn->priv is RCU
 	 * protected for this access.  See css_release_work_fn() for details.
 	 */
-	cgrp = rcu_dereference(kn->priv);
+	cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
 	if (cgrp)
 		css = cgroup_css(cgrp, ss);
 
-- 
2.9.3

  parent reply	other threads:[~2016-12-22 17:29 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-20 21:08 [PATCHSET] cgroup: reorganize cgroup source files Tejun Heo
2016-12-20 21:08 ` Tejun Heo
2016-12-20 21:08 ` [PATCH 1/8] cgroup: reorder css_set fields Tejun Heo
2016-12-20 21:08 ` [PATCH 2/8] cgroup: move cgroup files under kernel/cgroup/ Tejun Heo
2016-12-20 21:08   ` Tejun Heo
2016-12-20 21:08 ` [PATCH 3/8] cgroup: move cgroup v1 specific code to kernel/cgroup/cgroup-v1.c Tejun Heo
2016-12-20 22:00   ` [PATCH v2 " Tejun Heo
2016-12-20 22:00     ` Tejun Heo
2016-12-20 21:08 ` [PATCH 4/8] cgroup: refactor mount path and clearly distinguish v1 and v2 paths Tejun Heo
2016-12-20 21:08 ` [PATCH 5/8] cgroup: separate out cgroup1_kf_syscall_ops Tejun Heo
2016-12-20 21:08 ` [PATCH 6/8] cgroup: move v1 mount functions to kernel/cgroup/cgroup-v1.c Tejun Heo
2016-12-20 21:08   ` Tejun Heo
2016-12-20 21:08 ` [PATCH 7/8] cgroup: rename functions for consistency Tejun Heo
2016-12-20 21:08 ` [PATCH 8/8] cgroup: move namespace code to kernel/cgroup/namespace.c Tejun Heo
2016-12-20 21:08   ` Tejun Heo
2016-12-22 17:29 ` Tejun Heo [this message]
2016-12-22 17:29   ` [PATCH 9/8] cgroup: fix RCU related sparse warnings Tejun Heo
2016-12-26  6:23 ` [PATCHSET] cgroup: reorganize cgroup source files Zefan Li
2016-12-26  6:23   ` Zefan Li
2016-12-27 19:53 ` Tejun Heo
2016-12-27 19:53   ` Tejun Heo

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