linux-kernel - [PATCH v2 06/11] lib/vsprintf: introduce %pl to print in human-readable form

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Date:	Fri, 15 Jan 2016 00:23:36 +0200
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Robert Elliott <elliott@....com>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Brian Norris <computersforpeace@...il.com>,
	Hariprasad S <hariprasad@...lsio.com>
Cc:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v2 06/11] lib/vsprintf: introduce %pl to print in human-readable form

Introduce a new extension for printing given unsigned long long value in
human-readable form with automatically choosen IEC binary prefix. The value is
passed by reference.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 Documentation/printk-formats.txt | 11 +++++++++++
 lib/test_printf.c                | 21 +++++++++++++++++++++
 lib/vsprintf.c                   | 26 +++++++++++++++++++++++++-
 3 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 5d1128b..8e8b4c0 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -287,6 +287,17 @@ struct clk:
 
 	Passed by reference.
 
+unsigned long long value in human-readable form (with IEC binary prefix):
+
+	%pl		1023 KiB	(1047552)
+	%pl		1048575 B	(1048575)
+	%pl		1 MiB		(1048576)
+
+	For printing given unsigned long long value in human-readable form with
+	automatically choosen IEC binary prefix.
+
+	Passed by reference.
+
 bitmap and its derivatives such as cpumask and nodemask:
 
 	%*pb	0779
diff --git a/lib/test_printf.c b/lib/test_printf.c
index fd985f6..1e078c2 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -407,6 +407,26 @@ bitmap(void)
 }
 
 static void __init
+human_readable(void)
+{
+	struct hr_test_data {
+		unsigned long long v;
+		const char *r;
+	};
+	struct hr_test_data htdpl[] = {
+		{ .v = 1097364144128ULL,	.r = "1022 GiB" },
+		{ .v = 1097364144125ULL,	.r = "1097364144125 B" },
+		{ .v = 1048576ULL,		.r = "1 MiB" },
+		{ .v = 1048575ULL,		.r = "1048575 B" },
+		{ .v = 1047552ULL,		.r = "1023 KiB" },
+	};
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(htdpl); i++)
+		test(htdpl[i].r, "%pl", &htdpl[i].v);
+}
+
+static void __init
 netdev_features(void)
 {
 }
@@ -428,6 +448,7 @@ test_pointer(void)
 	struct_va_format();
 	struct_clk();
 	bitmap();
+	human_readable();
 	netdev_features();
 }
 
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index f0789e3..8288470 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1306,6 +1306,28 @@ char *uuid_string(char *buf, char *end, const u8 *addr,
 }
 
 static noinline_for_stack
+char *human_readable(char *buf, char *end, const void *addr,
+		     struct printf_spec spec, const char *fmt)
+{
+	unsigned long long value = *(unsigned long long *)addr;
+	unsigned long index;
+
+	if (value)
+		index = __ffs64(value) / 10;
+	else
+		index = 0;
+
+	/* Print numeric part */
+	buf = number(buf, end, value >> (index * 10), default_dec_spec);
+
+	/* Space between numeric part and units */
+	buf = put_one_char(buf, end, ' ');
+
+	/* Print units */
+	return string(buf, end, string_units_2[index], default_str_spec);
+}
+
+static noinline_for_stack
 char *netdev_bits(char *buf, char *end, const void *addr, const char *fmt)
 {
 	unsigned long long num;
@@ -1437,6 +1459,7 @@ int kptr_restrict __read_mostly;
  *       Do not use this feature without some mechanism to verify the
  *       correctness of the format string and va_list arguments.
  * - 'K' For a kernel pointer that should be hidden from unprivileged users
+ * - 'l' For a value in human-readable form (with IEC binary prefix)
  * - 'NF' For a netdev_features_t
  * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with
  *            a certain separator (' ' by default):
@@ -1590,7 +1613,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 			break;
 		}
 		break;
-
+	case 'l':
+		return human_readable(buf, end, ptr, spec, fmt);
 	case 'N':
 		return netdev_bits(buf, end, ptr, fmt);
 	case 'a':
-- 
2.6.4