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Date: Tue, 3 Jul 2012 13:06:39 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Andrew Morton <akpm@...ux-foundation.org>, proski@....org,
Andrei Emeltchenko <andrei.emeltchenko@...el.com>,
linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
Joe@...le, Perches@...le, joe@...ches.com
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [RFC][PATCHv2 2/3] lib: printf: append support of '%*p[Mm][FR]'
There are many places in the kernel where the drivers print small buffers as a
hex string. This patch adds a support of the variable width buffer to print it
as a hex string with a delimiter. The idea came from Pavel Roskin here:
http://www.digipedia.pl/usenet/thread/18835/17449/
Sample output of
pr_info("buf[%d:%d] %*pM\n", from, len, len, &buf[from]);
could be look like this:
[ 0.726130] buf[51:8] e8:16:b6:ef:e3:74:45:6e
[ 0.750736] buf[59:15] 31:81:b8:3f:35:49:06:ae:df:32:06:05:4a:af:55
[ 0.757602] buf[17:5] ac:16:d5:2c:ef
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
Documentation/printk-formats.txt | 5 ++++
lib/vsprintf.c | 49 ++++++++++++++++++++++++++------------
2 files changed, 39 insertions(+), 15 deletions(-)
diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 90ff4d7..3ae3d32 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -73,6 +73,11 @@ MAC/FDDI addresses:
specifier to use reversed byte order suitable for visual interpretation
of Bluetooth addresses which are in the little endian order.
+ Optional usage of all of the above is to specify variable length via
+ putting '*' into the specificator ('%*p[Mm][FR]'). In this case it will
+ print up to 64 bytes of the input as a hex string with certain
+ separator. For larger buffers consider to use print_hex_dump().
+
IPv4 addresses:
%pI4 1.2.3.4
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index c65f5d4..ef4bbd2 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -655,12 +655,13 @@ char *resource_string(char *buf, char *end, struct resource *res,
}
static noinline_for_stack
-char *mac_address_string(char *buf, char *end, u8 *addr,
- struct printf_spec spec, const char *fmt)
+char *hex_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
+ const char *fmt)
{
- char mac_addr[sizeof("xx:xx:xx:xx:xx:xx")];
- char *p = mac_addr;
- int i;
+ char hex_str[8*3+1]; /* support up to 8 bytes to print */
+ int len = 6; /* default length is 6 bytes */
+ char *p;
+ int i = 0, j;
char separator;
bool reversed = false;
@@ -678,18 +679,31 @@ char *mac_address_string(char *buf, char *end, u8 *addr,
break;
}
- for (i = 0; i < 6; i++) {
- if (reversed)
- p = hex_byte_pack(p, addr[5 - i]);
- else
- p = hex_byte_pack(p, addr[i]);
+ if (spec.field_width > 0)
+ len = min_t(int, spec.field_width, 64);
+
+ while (i < len) {
+ p = hex_str;
+ for (j = 0; j < 8 && i < len; j++) {
+ if (reversed)
+ p = hex_byte_pack(p, addr[len - 1 - i]);
+ else
+ p = hex_byte_pack(p, addr[i]);
+
+ if (fmt[0] == 'M' && i != len - 1)
+ *p++ = separator;
+ i++;
+ }
+ *p = '\0';
- if (fmt[0] == 'M' && i != 5)
- *p++ = separator;
+ for (p = hex_str; *p != '\0'; p++) {
+ if (buf < end)
+ *buf = *p;
+ ++buf;
+ }
}
- *p = '\0';
- return string(buf, end, mac_addr, spec);
+ return buf;
}
static noinline_for_stack
@@ -947,6 +961,9 @@ int kptr_restrict __read_mostly;
* - 'MF' For a 6-byte MAC FDDI address, it prints the address
* with a dash-separated hex notation
* - '[mM]R For a 6-byte MAC address, Reverse order (Bluetooth)
+ * Optional usage is %*p[Mn][FR] with variable length to print. It
+ * supports up to 64 bytes of the input. Consider to use print_hex_dump()
+ * for the larger input.
* - 'I' [46] for IPv4/IPv6 addresses printed in the usual way
* IPv4 uses dot-separated decimal without leading 0's (1.2.3.4)
* IPv6 uses colon separated network-order 16 bit hex with leading 0's
@@ -1011,7 +1028,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
case 'm': /* Contiguous: 000102030405 */
/* [mM]F (FDDI) */
/* [mM]R (Reverse order; Bluetooth) */
- return mac_address_string(buf, end, ptr, spec, fmt);
+ return hex_string(buf, end, ptr, spec, fmt);
case 'I': /* Formatted IP supported
* 4: 1.2.3.4
* 6: 0001:0203:...:0708
@@ -1291,6 +1308,8 @@ qualifier:
* %pMF output a 6-byte MAC address with dashes
* %pm output a 6-byte MAC address without colons
* %pmR output a 6-byte MAC address without colons in reversed order
+ * %*p[Mm][FR] a variable-length hex string with a separator (supports up to 64
+ * bytes of the input)
* %pI4 print an IPv4 address without leading zeros
* %pi4 print an IPv4 address with leading zeros
* %pI6 print an IPv6 address with colons
--
1.7.10
--
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