linux-kernel - Re: [PATCH 1/3] x86: modify show_shared_cpu_map in intel

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Message-Id: <20080410085740.a7e08672.pj@sgi.com>
Date:	Thu, 10 Apr 2008 08:57:40 -0500
From:	Paul Jackson <pj@....com>
To:	Mike Travis <travis@....com>
Cc:	mingo@...e.hu, bert.wesarg@...glemail.com, tglx@...utronix.de,
	hpa@...or.com, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] x86: modify show_shared_cpu_map in intel_cacheinfo
 v3

Mike wrote:
+		n = type?
+			cpulist_scnprintf(buf, len-2, *mask):
+			cpumask_scnprintf(buf, len-2, *mask);

I suspect most of us would find the following variant easier to read:

		if (type)
			n = cpulist_scnprintf(buf, len - 2, *mask);
		else
			n = cpumask_scnprintf(buf, len - 2, *mask);


Then, going further, the rather too vague "type" parameter name,
without comment and taking just bare constant values 0 or 1, seems
more opaque than necessary.

I can imagine this being easier to read as something like:


typedef enum { print_as_mask, print_as_list } map_printer_t;

static ssize_t show_shared_cpu_map_func(struct _cpuid4_info *this_leaf,
				       map_printer_t mpt, char *buf)
{
       ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf;
       int n = 0;

       if (len > 1) {
		cpumask_t *mask = &this_leaf->shared_cpu_map;

		if (mpt == print_as_mask)
			n = cpumask_scnprintf(buf, len - 2, *mask);
		else
			n = cpulist_scnprintf(buf, len - 2, *mask);
		buf[n++] = '\n';
		buf[n] = '\0';
       }
       return n;
}

static inline ssize_t show_shared_cpu_map(struct _cpuid4_info *leaf, char *buf)
{
       return show_shared_cpu_map_func(leaf, print_as_mask, buf);
}

static inline ssize_t show_shared_cpu_list(struct _cpuid4_info *leaf, char *buf)
{
       return show_shared_cpu_map_func(leaf, print_as_list, buf);
}



-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@....com> 1.940.382.4214
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