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Date: Tue, 13 Feb 2024 15:53:09 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Vincent Donnefort <vdonnefort@google.com>
Cc: mhiramat@kernel.org, linux-kernel@vger.kernel.org,
 linux-trace-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com,
 kernel-team@android.com
Subject: Re: [PATCH v17 2/6] ring-buffer: Introducing ring-buffer mapping
 functions
Message-ID: <20240213155309.01c7c2b2@gandalf.local.home>
In-Reply-To: <20240213114945.3528801-3-vdonnefort@google.com>
References: <20240213114945.3528801-1-vdonnefort@google.com>
	<20240213114945.3528801-3-vdonnefort@google.com>
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On Tue, 13 Feb 2024 11:49:41 +0000
Vincent Donnefort <vdonnefort@google.com> wrote:

Did you test with lockdep?

> +static int __rb_inc_dec_mapped(struct trace_buffer *buffer,
> +			       struct ring_buffer_per_cpu *cpu_buffer,
> +			       bool inc)
> +{
> +	unsigned long flags;
> +
> +	lockdep_assert_held(cpu_buffer->mapping_lock);

/work/git/linux-trace.git/kernel/trace/ring_buffer.c: In function =E2=80=98=
__rb_inc_dec_mapped=E2=80=99:
/work/git/linux-trace.git/include/linux/lockdep.h:234:61: error: invalid ty=
pe argument of =E2=80=98->=E2=80=99 (have =E2=80=98struct mutex=E2=80=99)
  234 | #define lockdep_is_held(lock)           lock_is_held(&(lock)->dep_m=
ap)
      |                                                             ^~
/work/git/linux-trace.git/include/asm-generic/bug.h:123:32: note: in defini=
tion of macro =E2=80=98WARN_ON=E2=80=99
  123 |         int __ret_warn_on =3D !!(condition);                       =
       \
      |                                ^~~~~~~~~
/work/git/linux-trace.git/include/linux/lockdep.h:267:9: note: in expansion=
 of macro =E2=80=98lockdep_assert=E2=80=99
  267 |         lockdep_assert(lockdep_is_held(l) !=3D LOCK_STATE_NOT_HELD)
      |         ^~~~~~~~~~~~~~
/work/git/linux-trace.git/include/linux/lockdep.h:267:24: note: in expansio=
n of macro =E2=80=98lockdep_is_held=E2=80=99
  267 |         lockdep_assert(lockdep_is_held(l) !=3D LOCK_STATE_NOT_HELD)
      |                        ^~~~~~~~~~~~~~~
/work/git/linux-trace.git/kernel/trace/ring_buffer.c:6167:9: note: in expan=
sion of macro =E2=80=98lockdep_assert_held=E2=80=99
 6167 |         lockdep_assert_held(cpu_buffer->mapping_lock);
      |         ^~~~~~~~~~~~~~~~~~~

I believe that is supposed to be:

	lockdep_assert_held(&cpu_buffer->mapping_lock);

-- Steve

> +
> +	if (inc && cpu_buffer->mapped =3D=3D UINT_MAX)
> +		return -EBUSY;
> +
> +	if (WARN_ON(!inc && cpu_buffer->mapped =3D=3D 0))
> +		return -EINVAL;
> +
> +	mutex_lock(&buffer->mutex);
> +	raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
> +
> +	if (inc)
> +		cpu_buffer->mapped++;
> +	else
> +		cpu_buffer->mapped--;
> +
> +	raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
> +	mutex_unlock(&buffer->mutex);
> +
> +	return 0;
> +}