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From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
	jiangshanlai@gmail.com, dipankar@in.ibm.com,
	akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
	josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
	rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
	fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
	"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH tip/core/rcu 9/9] rcu: Suppress levelspread uninitialized messages
Date: Wed,  2 Oct 2019 18:47:28 -0700
Message-ID: <20191003014728.13496-9-paulmck@kernel.org> (raw)
In-Reply-To: <20191003014710.GA13323@paulmck-ThinkPad-P72>

From: "Paul E. McKenney" <paulmck@kernel.org>

New tools bring new warnings, and with v5.3 comes:

kernel/rcu/srcutree.c: warning: 'levelspread[<U aa0>]' may be used uninitialized in this function [-Wuninitialized]:  => 121:34

This commit suppresses this warning by initializing the full array
to INT_MIN, which will result in failures should any out-of-bounds
references appear.

Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/rcu/rcu.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index aeec70f..ab504fb 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -299,6 +299,8 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
 {
 	int i;
 
+	for (i = 0; i < RCU_NUM_LVLS; i++)
+		levelspread[i] = INT_MIN;
 	if (rcu_fanout_exact) {
 		levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
 		for (i = rcu_num_lvls - 2; i >= 0; i--)
-- 
2.9.5


  parent reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-03  1:47 [PATCH tip/core/rcu 0/9] Torture-test updates Paul E. McKenney
2019-10-03  1:47 ` [PATCH tip/core/rcu 1/9] rcu: Remove unused function rcutorture_record_progress() paulmck
2019-10-03  1:47 ` [PATCH tip/core/rcu 2/9] locktorture: Replace strncmp() with str_has_prefix() paulmck
2019-10-03  1:47 ` [PATCH tip/core/rcu 3/9] rcutorture: Remove CONFIG_HOTPLUG_CPU=n from scenarios paulmck
2019-10-03  1:47 ` [PATCH tip/core/rcu 4/9] rcutorture: Emulate dyntick aspect of userspace nohz_full sojourn paulmck
2019-10-03  1:47 ` [PATCH tip/core/rcu 5/9] rcu: Remove unused variable rcu_perf_writer_state paulmck
2019-10-03  1:47 ` [PATCH tip/core/rcu 6/9] rcutorture: Separate warnings for each failure type paulmck
2019-10-03  1:47 ` [PATCH tip/core/rcu 7/9] rcutorture: Make in-kernel-loop testing more brutal paulmck
2019-10-03  1:47 ` [PATCH tip/core/rcu 8/9] locking: locktorture: Do not include rwlock.h directly paulmck
2019-10-03  1:47 ` paulmck [this message]
2019-10-03  8:53   ` [PATCH tip/core/rcu 9/9] rcu: Suppress levelspread uninitialized messages Geert Uytterhoeven
2019-10-05 16:16     ` Paul E. McKenney

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