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From:   "Paul E. McKenney" <paulmck@kernel.org>
To:     linux-kernel@vger.kernel.org
Cc:     gwml@vger.gnuweeb.org, kernel-team@fb.com, w@lwt.eu,
        Zqiang <qiang1.zhang@intel.com>,
        "Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH rcu 2/2] rcutorture: Use the barrier operation specified by cur_ops
Date:   Wed, 31 Aug 2022 11:21:31 -0700
Message-Id: <20220831182148.2698489-3-paulmck@kernel.org>
In-Reply-To: <20220831182113.GA2697286@paulmck-ThinkPad-P17-Gen-1>
References: <20220831182113.GA2697286@paulmck-ThinkPad-P17-Gen-1>
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From: Zqiang <qiang1.zhang@intel.com>

The rcutorture_oom_notify() function unconditionally invokes
rcu_barrier(), which is OK when the rcutorture.torture_type value is
"rcu", but unhelpful otherwise.  The purpose of these barrier calls is to
wait for all outstanding callback-flooding callbacks to be invoked before
cleaning up their data.  Using the wrong barrier function therefore
risks arbitrary memory corruption.  Thus, this commit changes these
rcu_barrier() calls into cur_ops->cb_barrier() to make things work when
torturing non-vanilla flavors of RCU.

Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/rcu/rcutorture.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index d8e1b270a065f..08b7b59d5d05b 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2600,12 +2600,12 @@ static int rcutorture_oom_notify(struct notifier_block *self,
 	for (i = 0; i < fwd_progress; i++)
 		ncbs += rcu_torture_fwd_prog_cbfree(&rfp[i]);
 	pr_info("%s: Freed %lu RCU callbacks.\n", __func__, ncbs);
-	rcu_barrier();
+	cur_ops->cb_barrier();
 	ncbs = 0;
 	for (i = 0; i < fwd_progress; i++)
 		ncbs += rcu_torture_fwd_prog_cbfree(&rfp[i]);
 	pr_info("%s: Freed %lu RCU callbacks.\n", __func__, ncbs);
-	rcu_barrier();
+	cur_ops->cb_barrier();
 	ncbs = 0;
 	for (i = 0; i < fwd_progress; i++)
 		ncbs += rcu_torture_fwd_prog_cbfree(&rfp[i]);
-- 
2.31.1.189.g2e36527f23