From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:60861)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <serge.fdrv@gmail.com>) id 1bG5ih-0000Ot-Bs
	for qemu-devel@nongnu.org; Thu, 23 Jun 2016 10:35:04 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <serge.fdrv@gmail.com>) id 1bG5ic-0001qC-Ag
	for qemu-devel@nongnu.org; Thu, 23 Jun 2016 10:35:02 -0400
Received: from mail-lf0-x242.google.com ([2a00:1450:4010:c07::242]:36534)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <serge.fdrv@gmail.com>) id 1bG5ic-0001pa-2e
	for qemu-devel@nongnu.org; Thu, 23 Jun 2016 10:34:58 -0400
Received: by mail-lf0-x242.google.com with SMTP id a2so18486374lfe.3
	for <qemu-devel@nongnu.org>; Thu, 23 Jun 2016 07:34:57 -0700 (PDT)
References: <1464986428-6739-1-git-send-email-alex.bennee@linaro.org>
	<1464986428-6739-4-git-send-email-alex.bennee@linaro.org>
From: Sergey Fedorov <serge.fdrv@gmail.com>
Message-ID: <576BF38E.2000408@gmail.com>
Date: Thu, 23 Jun 2016 17:34:54 +0300
MIME-Version: 1.0
In-Reply-To: <1464986428-6739-4-git-send-email-alex.bennee@linaro.org>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Subject: Re: [Qemu-devel] [RFC v3 03/19] translate-all: add DEBUG_LOCKING
 asserts
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: =?UTF-8?Q?Alex_Benn=c3=a9e?= <alex.bennee@linaro.org>, mttcg@listserver.greensocs.com, qemu-devel@nongnu.org, fred.konrad@greensocs.com, a.rigo@virtualopensystems.com, cota@braap.org, bobby.prani@gmail.com
Cc: mark.burton@greensocs.com, pbonzini@redhat.com, jan.kiszka@siemens.com, rth@twiddle.net, peter.maydell@linaro.org, claudio.fontana@huawei.com, Blue Swirl <blauwirbel@gmail.com>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, Riku Voipio <riku.voipio@iki.fi>

On 03/06/16 23:40, Alex Bennée wrote:
> diff --git a/translate-all.c b/translate-all.c
> index ec6fdbb..e3f44d9 100644
> --- a/translate-all.c
> +++ b/translate-all.c
(snip)
> @@ -60,6 +61,7 @@
>  
>  /* #define DEBUG_TB_INVALIDATE */
>  /* #define DEBUG_TB_FLUSH */
> +/* #define DEBUG_LOCKING */

A bit of bikeshedding: have you considered naming it 'DEBUG_LOCKS'. How
does it sound for a native English speaker? :)

>  /* make various TB consistency checks */
>  /* #define DEBUG_TB_CHECK */
>  
> @@ -68,6 +70,28 @@
>  #undef DEBUG_TB_CHECK
>  #endif
>  
> +/* Access to the various translations structures need to be serialised via locks
> + * for consistency. This is automatic for SoftMMU based system
> + * emulation due to its single threaded nature. In user-mode emulation
> + * access to the memory related structures are protected with the
> + * mmap_lock.
> + */
> +#ifdef DEBUG_LOCKING
> +#define DEBUG_MEM_LOCKS 1
> +#else
> +#define DEBUG_MEM_LOCKS 0
> +#endif
> +
> +#ifdef CONFIG_SOFTMMU
> +#define assert_memory_lock() do { /* nothing */ } while (0)
> +#else
> +#define assert_memory_lock() do {               \
> +        if (DEBUG_MEM_LOCKS) {                  \
> +            g_assert(have_mmap_lock());         \
> +        }                                       \
> +    } while (0)
> +#endif
> +

Why not simply:

#if !defined(DEBUG_LOCKING) || defined(CONFIG_SOFTMMU)
#    define assert_memory_lock() do { /* nothing */ } while (0)
#else
#    define assert_memory_lock() g_assert(have_mmap_lock())
#endif

One more nit: maybe it would be a bit more clear to name it after the
lock name, i.e. assert_mmap_lock(), or check_mmap_lock(), or
debug_mmap_lock() etc?

Thanks,
Sergey