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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: paulmck@kernel.org
Cc: rcu@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	dipankar@in.ibm.com, Andrew Morton <akpm@linux-foundation.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	David Howells <dhowells@redhat.com>,
	Eric Dumazet <edumazet@google.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH tip/core/rcu 9/9] rcu: Suppress levelspread uninitialized messages
Date: Thu, 3 Oct 2019 10:53:03 +0200
Message-ID: <CAMuHMdW5+RSp6iycmyPnYPv+xHr5tNY7U3w-BVrWqz4BR2Dd7w@mail.gmail.com> (raw)
In-Reply-To: <20191003014728.13496-9-paulmck@kernel.org>

Hi Paul,

On Thu, Oct 3, 2019 at 3:49 AM <paulmck@kernel.org> wrote:
> From: "Paul E. McKenney" <paulmck@kernel.org>
> New tools bring new warnings, and with v5.3 comes:

According to the kisskb build logs, it happens with gcc 4.6.3 only ;-)

> 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>

Thanks for your patch!

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
(for the initialization loop, not for the actual INT_MIN value)

Unfortunately I don't have a gcc-4.6.3 Linux cross-compiler anymore.
I tried with msp430-gcc-4.6.3 and some hackery to get it to compile,
but that didn't let me reproduce the warning.



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

  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 ` [PATCH tip/core/rcu 9/9] rcu: Suppress levelspread uninitialized messages paulmck
2019-10-03  8:53   ` Geert Uytterhoeven [this message]
2019-10-05 16:16     ` Paul E. McKenney

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