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Date: Tue, 25 Aug 2015 17:16:28 +0100
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20150825161628.GF8344@stefanha-thinkpad.redhat.com>
References: <1439563931-12352-1-git-send-email-guangrong.xiao@linux.intel.com>
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In-Reply-To: <1439563931-12352-14-git-send-email-guangrong.xiao@linux.intel.com>
Subject: Re: [Qemu-devel] [PATCH v2 13/18] nvdimm: build namespace config
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To: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: ehabkost@redhat.com, kvm@vger.kernel.org, mst@redhat.com, gleb@kernel.org, mtosatti@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com, imammedo@redhat.com, pbonzini@redhat.com, rth@twiddle.net

On Fri, Aug 14, 2015 at 10:52:06PM +0800, Xiao Guangrong wrote:
> +#ifdef NVDIMM_DEBUG
> +#define nvdebug(fmt, ...) fprintf(stderr, "nvdimm: " fmt, ## __VA_ARGS__)
> +#else
> +#define nvdebug(...)
> +#endif

The following allows the compiler to check format strings and syntax
check the argument expressions:

#define NVDIMM_DEBUG 0  /* set to 1 for debug output */
#define nvdebug(fmt, ...) \
    if (NVDIMM_DEBUG) { \
        fprintf(stderr, "nvdimm: " fmt, ## __VA_ARGS__); \
    }

This approach avoids bitrot (e.g. debug format string arguments have
become outdated).