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Date: Fri, 28 Aug 2015 12:59:55 +0100
From: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20150828115955.GN4917@stefanha-thinkpad.redhat.com>
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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, Stefan Hajnoczi <stefanha@gmail.com>, mtosatti@redhat.com, qemu-devel@nongnu.org, pbonzini@redhat.com, imammedo@redhat.com, rth@twiddle.net

On Wed, Aug 26, 2015 at 06:42:01PM +0800, Xiao Guangrong wrote:
> 
> 
> On 08/26/2015 12:16 AM, Stefan Hajnoczi wrote:
> >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become outdated).
> >
> 
> Really good tips, thanks for your sharing.

I forgot the do { ... } while (0) in the macro to make nvdebug("hello
world"); work like a normal C statement.