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[PATCH] lib/vsprintf.c: Add %pMF to format FDDI bit reversed MAC addresses

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Joe Perches

unread,
Jan 7, 2010, 1:30:02 PM1/7/10
to
On Mon, 2010-01-04 at 23:43 +0000, Maciej W. Rozycki wrote:
> The example below shows an address, and the sequence of bits or symbols
> that would be transmitted when the address is used in the Source Address
> or Destination Address fields on the MAC header. The transmission line
> shows the address bits in the order transmitted, from left to right. For
> IEEE 802 LANs these correspond to actual bits on the medium. The FDDI
> symbols line shows how the FDDI PHY sends the address bits as encoded
> symbols.
>
> MSB: 35:7B:12:00:00:01
> Canonical: AC-DE-48-00-00-80
> Transmission: 00110101 01111011 00010010 00000000 00000000 00000001
> FDDI Symbols: 35 7B 12 00 00 01"
>
> Please note that this address has its group bit clear.
>
> This notation is also defined in the "FDDI MEDIA ACCESS CONTROL-2
> (MAC-2)" (X3T9/92-120) document although that book does not have a need
> to use the MSB form and it's skipped.

Adds 56 bytes to object size

New:
$ size lib/vsprintf.o
text data bss dec hex filename
8714 0 2 8716 220c lib/vsprintf.o
old:
$ size lib/vsprintf.o
text data bss dec hex filename
8658 0 2 8660 21d4 lib/vsprintf.o

Signed-off-by: Joe Perches <j...@perches.com>
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index d4996cf..36959cc 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -25,6 +25,7 @@
#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/ioport.h>
+#include <linux/bitrev.h>
#include <net/addrconf.h>

#include <asm/page.h> /* for PAGE_SIZE */
@@ -675,17 +676,37 @@ static char *resource_string(char *buf, char *end, struct resource *res,
return string(buf, end, sym, spec);
}

+static u8 mac_byte(u8 val)
+{
+ return val;
+}
+
+static u8 mac_byte_rev(u8 val)
+{
+ return bitrev8(val);
+}
+
static char *mac_address_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;
+ u8 (*mac_byte_fn)(u8 val);
+ char separator;
+
+ if (fmt[1] == 'F') { /* FDDI canonical format */
+ mac_byte_fn = mac_byte_rev;
+ separator = '-';
+ } else {
+ mac_byte_fn = mac_byte;
+ separator = ':';
+ }

for (i = 0; i < 6; i++) {
- p = pack_hex_byte(p, addr[i]);
+ p = pack_hex_byte(p, mac_byte_fn(addr[i]));
if (fmt[0] == 'M' && i != 5)
- *p++ = ':';
+ *p++ = separator;
}
*p = '\0';

@@ -896,6 +917,10 @@ static char *uuid_string(char *buf, char *end, const u8 *addr,
* - 'M' For a 6-byte MAC address, it prints the address in the
* usual colon-separated hex notation
* - 'm' For a 6-byte MAC address, it prints the hex address without colons
+ * - 'MF' For a 6-byte MAC FDDI address, it prints the address
+ * with a dash-separated hex notation with bit reversed bytes
+ * - 'mF' For a 6-byte MAC FDDI address, it prints the address
+ * in hex notation without separators with bit reversed bytes
* - '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
@@ -939,6 +964,7 @@ static char *pointer(const char *fmt, char *buf, char *end, void *ptr,
return resource_string(buf, end, ptr, spec, fmt);
case 'M': /* Colon separated: 00:01:02:03:04:05 */
case 'm': /* Contiguous: 000102030405 */
+ /* [mM]F (FDDI, bit reversed) */
return mac_address_string(buf, end, ptr, spec, fmt);
case 'I': /* Formatted IP supported
* 4: 1.2.3.4


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Maciej W. Rozycki

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Jan 7, 2010, 3:50:02 PM1/7/10
to

What's the gain? I'd be rather conservative when taking everybody's 56
bytes for one or two drivers hardly anybody uses. The format of MAC
addresses is unlikely to change, so I'd say the sources can live with
one or two places where the strings are formatted manually. Even if the
drivers lose more than these 56 bytes.

Maciej

Michał Mirosław

unread,
Jan 7, 2010, 4:20:02 PM1/7/10
to
2010/1/7 Maciej W. Rozycki <ma...@linux-mips.org>:

> On Thu, 7 Jan 2010, Joe Perches wrote:
>> On Mon, 2010-01-04 at 23:43 +0000, Maciej W. Rozycki wrote:
>> > The example below shows an address, and the sequence of bits or symbols
>> > that would be transmitted when the address is used in the Source Address
>> > or Destination Address fields on the MAC header. �The transmission line
>> > shows the address bits in the order transmitted, from left to right. �For
>> > IEEE 802 LANs these correspond to actual bits on the medium. �The FDDI

>> > symbols line shows how the FDDI PHY sends the address bits as encoded
>> > symbols.
>> >
>> > � � � � MSB: � � � � � �35:7B:12:00:00:01
>> > � � � � Canonical: � � �AC-DE-48-00-00-80
>> > ďż˝ ďż˝ ďż˝ ďż˝ Transmission: ďż˝ 00110101 01111011 00010010 00000000 00000000 00000001
>> > ďż˝ ďż˝ ďż˝ ďż˝ FDDI Symbols: ďż˝ 35 7B 12 00 00 01"

>> >
>> > Please note that this address has its group bit clear.
>> >
>> > �This notation is also defined in the "FDDI MEDIA ACCESS CONTROL-2

>> > (MAC-2)" (X3T9/92-120) document although that book does not have a need
>> > to use the MSB form and it's skipped.
>>
>> Adds 56 bytes to object size
>>
>> New:
>> $ size lib/vsprintf.o
>> � �text � � � � �data � � bss � � dec � � hex filename
>> � �8714 � � � � � � 0 � � � 2 � �8716 � �220c lib/vsprintf.o
>> old:
>> $ size lib/vsprintf.o
>> � �text � � � � �data � � bss � � dec � � hex filename
>> � �8658 � � � � � � 0 � � � 2 � �8660 � �21d4 lib/vsprintf.o
>
> �What's the gain? �I'd be rather conservative when taking everybody's 56
> bytes for one or two drivers hardly anybody uses. �The format of MAC

> addresses is unlikely to change, so I'd say the sources can live with
> one or two places where the strings are formatted manually. �Even if the

> drivers lose more than these 56 bytes.

Maybe this can be Kconfig-selected by the relevant drivers then?

BTW, the gain is of course consistency and code readability.

Best Regards,
Micha� Miros�aw

Michał Mirosław

unread,
Jan 7, 2010, 4:20:02 PM1/7/10
to
2010/1/7 Joe Perches <j...@perches.com>:
[...]

> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index d4996cf..36959cc 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -25,6 +25,7 @@
> ďż˝#include <linux/kallsyms.h>
> ďż˝#include <linux/uaccess.h>
> ďż˝#include <linux/ioport.h>
> +#include <linux/bitrev.h>
> ďż˝#include <net/addrconf.h>
>
> ďż˝#include <asm/page.h> ďż˝ ďż˝ ďż˝ ďż˝ ďż˝/* for PAGE_SIZE */

> @@ -675,17 +676,37 @@ static char *resource_string(char *buf, char *end, struct resource *res,
> � � � �return string(buf, end, sym, spec);
> ďż˝}

>
> +static u8 mac_byte(u8 val)
> +{
> + ďż˝ ďż˝ ďż˝ return val;

> +}
> +
> +static u8 mac_byte_rev(u8 val)
> +{
> + ďż˝ ďż˝ ďż˝ return bitrev8(val);
> +}
> +
> �static char *mac_address_string(char *buf, char *end, u8 *addr,
> � � � � � � � � � � � � � � � �struct printf_spec spec, const char *fmt)
> ďż˝{
> � � � �char mac_addr[sizeof("xx:xx:xx:xx:xx:xx")];
> � � � �char *p = mac_addr;
> � � � �int i;
> + ďż˝ ďż˝ ďż˝ u8 (*mac_byte_fn)(u8 val);
> + ďż˝ ďż˝ ďż˝ char separator;
> +
> + ďż˝ ďż˝ ďż˝ if (fmt[1] == 'F') { ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝/* FDDI canonical format */
> + ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ mac_byte_fn = mac_byte_rev;
> + ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ separator = '-';
> + ďż˝ ďż˝ ďż˝ } else {
> + ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ mac_byte_fn = mac_byte;
> + ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ separator ďż˝= ':';
> + ďż˝ ďż˝ ďż˝ }
>
> � � � �for (i = 0; i < 6; i++) {
> - ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ p = pack_hex_byte(p, addr[i]);
> + ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ p = pack_hex_byte(p, mac_byte_fn(addr[i]));
> � � � � � � � �if (fmt[0] == 'M' && i != 5)
> - ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ *p++ = ':';
> + ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ ďż˝ *p++ = separator;
> ďż˝ ďż˝ ďż˝ ďż˝}
> ďż˝ ďż˝ ďż˝ ďż˝*p = '\0';
>
[...]

Something like the following might be smaller and faster - no
functions and their calls (just an idea);

int rev = (fmt[1] == 'F');
...
p = pack_hex_byte(p, rev ? bitrev8(addr[i]) : addr[i]);

Best Regards,
Micha� Miros�aw

Joe Perches

unread,
Jan 7, 2010, 4:40:02 PM1/7/10
to
On Mon, 2010-01-04 at 23:43 +0000, Maciej W. Rozycki wrote:
> The example below shows an address, and the sequence of bits or symbols
> that would be transmitted when the address is used in the Source Address
> or Destination Address fields on the MAC header. The transmission line
> shows the address bits in the order transmitted, from left to right. For
> IEEE 802 LANs these correspond to actual bits on the medium. The FDDI
> symbols line shows how the FDDI PHY sends the address bits as encoded
> symbols.
>
> MSB: 35:7B:12:00:00:01
> Canonical: AC-DE-48-00-00-80
> Transmission: 00110101 01111011 00010010 00000000 00000000 00000001
> FDDI Symbols: 35 7B 12 00 00 01"
>
> Please note that this address has its group bit clear.
>
> This notation is also defined in the "FDDI MEDIA ACCESS CONTROL-2
> (MAC-2)" (X3T9/92-120) document although that book does not have a need
> to use the MSB form and it's skipped.

Adds 6 bytes to object size for x86

New:
$ size lib/vsprintf.o
text data bss dec hex filename

8664 0 2 8666 21da lib/vsprintf.o


$ size lib/vsprintf.o
text data bss dec hex filename
8658 0 2 8660 21d4 lib/vsprintf.o

Signed-off-by: Joe Perches <j...@perches.com>On Thu, 2010-01-07 at 22:18 +0100, Michał Mirosław wrote:
diff --git a/lib/vsprintf.c b/lib/vsprintf.c

index d4996cf..dc48d2b 100644


--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -25,6 +25,7 @@

#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/ioport.h>
+#include <linux/bitrev.h>
#include <net/addrconf.h>

#include <asm/page.h> /* for PAGE_SIZE */
@@ -681,11 +682,21 @@ static char *mac_address_string(char *buf, char *end, u8 *addr,


char mac_addr[sizeof("xx:xx:xx:xx:xx:xx")];

char *p = mac_addr;
int i;

+ bool bitrev;
+ char separator;
+
+ if (fmt[1] == 'F') { /* FDDI canonical format */
+ bitrev = true;


+ separator = '-';
+ } else {

+ bitrev = false;
+ separator = ':';
+ }



for (i = 0; i < 6; i++) {

- p = pack_hex_byte(p, addr[i]);
+ p = pack_hex_byte(p, bitrev ? bitrev8(addr[i]) : addr[i]);


if (fmt[0] == 'M' && i != 5)

- *p++ = ':';
+ *p++ = separator;
}
*p = '\0';

@@ -896,6 +907,10 @@ static char *uuid_string(char *buf, char *end, const u8 *addr,


* - 'M' For a 6-byte MAC address, it prints the address in the
* usual colon-separated hex notation
* - 'm' For a 6-byte MAC address, it prints the hex address without colons
+ * - 'MF' For a 6-byte MAC FDDI address, it prints the address
+ * with a dash-separated hex notation with bit reversed bytes
+ * - 'mF' For a 6-byte MAC FDDI address, it prints the address
+ * in hex notation without separators with bit reversed bytes
* - '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

@@ -939,6 +954,7 @@ static char *pointer(const char *fmt, char *buf, char *end, void *ptr,


return resource_string(buf, end, ptr, spec, fmt);
case 'M': /* Colon separated: 00:01:02:03:04:05 */
case 'm': /* Contiguous: 000102030405 */
+ /* [mM]F (FDDI, bit reversed) */
return mac_address_string(buf, end, ptr, spec, fmt);
case 'I': /* Formatted IP supported
* 4: 1.2.3.4

Joe Perches

unread,
Jan 7, 2010, 4:40:02 PM1/7/10
to
On Thu, 2010-01-07 at 22:18 +0100, Michał Mirosław wrote:
> Something like the following might be smaller and faster - no
> functions and their calls
> int rev = (fmt[1] == 'F');
> p = pack_hex_byte(p, rev ? bitrev8(addr[i]) : addr[i]);

Right, better. Just 6 bytes (x86). Resubmitting.

Joe Perches

unread,
Jan 7, 2010, 4:50:02 PM1/7/10
to
On Mon, 2010-01-04 at 23:43 +0000, Maciej W. Rozycki wrote:
> The example below shows an address, and the sequence of bits or symbols
> that would be transmitted when the address is used in the Source Address
> or Destination Address fields on the MAC header. The transmission line
> shows the address bits in the order transmitted, from left to right. For
> IEEE 802 LANs these correspond to actual bits on the medium. The FDDI
> symbols line shows how the FDDI PHY sends the address bits as encoded
> symbols.
>
> MSB: 35:7B:12:00:00:01
> Canonical: AC-DE-48-00-00-80
> Transmission: 00110101 01111011 00010010 00000000 00000000 00000001
> FDDI Symbols: 35 7B 12 00 00 01"
>
> Please note that this address has its group bit clear.
>
> This notation is also defined in the "FDDI MEDIA ACCESS CONTROL-2
> (MAC-2)" (X3T9/92-120) document although that book does not have a need
> to use the MSB form and it's skipped.

Adds 6 bytes to object size for x86

New:


$ size lib/vsprintf.o
text data bss dec hex filename

8664 0 2 8666 21da lib/vsprintf.o

$ size lib/vsprintf.o
text data bss dec hex filename
8658 0 2 8660 21d4 lib/vsprintf.o

Signed-off-by: Joe Perches <j...@perches.com>
---
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index d4996cf..dc48d2b 100644


--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -25,6 +25,7 @@

#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/ioport.h>
+#include <linux/bitrev.h>
#include <net/addrconf.h>

#include <asm/page.h> /* for PAGE_SIZE */
@@ -681,11 +682,21 @@ static char *mac_address_string(char *buf, char *end, u8 *addr,


char mac_addr[sizeof("xx:xx:xx:xx:xx:xx")];

char *p = mac_addr;
int i;

+ bool bitrev;
+ char separator;
+
+ if (fmt[1] == 'F') { /* FDDI canonical format */
+ bitrev = true;


+ separator = '-';
+ } else {

+ bitrev = false;
+ separator = ':';
+ }

for (i = 0; i < 6; i++) {

- p = pack_hex_byte(p, addr[i]);
+ p = pack_hex_byte(p, bitrev ? bitrev8(addr[i]) : addr[i]);


if (fmt[0] == 'M' && i != 5)

- *p++ = ':';
+ *p++ = separator;
}
*p = '\0';

@@ -896,6 +907,10 @@ static char *uuid_string(char *buf, char *end, const u8 *addr,


* - 'M' For a 6-byte MAC address, it prints the address in the
* usual colon-separated hex notation
* - 'm' For a 6-byte MAC address, it prints the hex address without colons
+ * - 'MF' For a 6-byte MAC FDDI address, it prints the address
+ * with a dash-separated hex notation with bit reversed bytes
+ * - 'mF' For a 6-byte MAC FDDI address, it prints the address
+ * in hex notation without separators with bit reversed bytes
* - '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

@@ -939,6 +954,7 @@ static char *pointer(const char *fmt, char *buf, char *end, void *ptr,


return resource_string(buf, end, ptr, spec, fmt);
case 'M': /* Colon separated: 00:01:02:03:04:05 */
case 'm': /* Contiguous: 000102030405 */
+ /* [mM]F (FDDI, bit reversed) */
return mac_address_string(buf, end, ptr, spec, fmt);
case 'I': /* Formatted IP supported
* 4: 1.2.3.4

--

David Miller

unread,
Jan 7, 2010, 5:10:02 PM1/7/10
to
From: "Maciej W. Rozycki" <ma...@linux-mips.org>
Date: Thu, 7 Jan 2010 20:42:12 +0000 (GMT)

> What's the gain? I'd be rather conservative when taking everybody's 56
> bytes for one or two drivers hardly anybody uses. The format of MAC
> addresses is unlikely to change, so I'd say the sources can live with
> one or two places where the strings are formatted manually. Even if the
> drivers lose more than these 56 bytes.

We gain consistency. You know, the part that's completely bolixed
right now?

I'm applying Joe's patch and followon patches to make the driver's
use the new printf format.

David Miller

unread,
Jan 7, 2010, 5:20:01 PM1/7/10
to
From: Joe Perches <j...@perches.com>
Date: Thu, 07 Jan 2010 13:37:18 -0800

> Adds 6 bytes to object size for x86

Sweet!

Simon Horman

unread,
Jan 7, 2010, 7:10:01 PM1/7/10
to
On Thu, Jan 07, 2010 at 02:09:42PM -0800, David Miller wrote:
> From: "Maciej W. Rozycki" <ma...@linux-mips.org>
> Date: Thu, 7 Jan 2010 20:42:12 +0000 (GMT)
>
> > What's the gain? I'd be rather conservative when taking everybody's 56
> > bytes for one or two drivers hardly anybody uses. The format of MAC
> > addresses is unlikely to change, so I'd say the sources can live with
> > one or two places where the strings are formatted manually. Even if the
> > drivers lose more than these 56 bytes.
>
> We gain consistency. You know, the part that's completely bolixed
> right now?
>
> I'm applying Joe's patch and followon patches to make the driver's
> use the new printf format.

In the vein of this, would it be worth adding some modifier to %i4 to
print addresses for ftp helpers? That is, %u,%u,%u,%u. I think
there are currently two users of that format string after Joe's latest
round of updates.

The users are net/netfilter/ipvs/ip_vs_ftp.c and
net/ipv4/netfilter/nf_nat_ftp.c. Prior to Joe's latest
changes ip_vs_ftp.c used %d,%d,%d,%d.

David Miller

unread,
Jan 7, 2010, 8:00:01 PM1/7/10
to
From: Joe Perches <j...@perches.com>
Date: Thu, 07 Jan 2010 13:43:50 -0800

Applied.

Joe Perches

unread,
Jan 7, 2010, 9:00:02 PM1/7/10
to
On Fri, 2010-01-08 at 11:08 +1100, Simon Horman wrote:
> In the vein of this, would it be worth adding some modifier to %i4 to
> print addresses for ftp helpers? That is, %u,%u,%u,%u. I think
> there are currently two users of that format string after Joe's latest
> round of updates.

I think not. I think the comma separated uses
are unusual enough to not support in lib/vsprintf.

I did submit a patch to support format strings
for le32 and u32 ipv4 addresses.

> The users are net/netfilter/ipvs/ip_vs_ftp.c and
> net/ipv4/netfilter/nf_nat_ftp.c. Prior to Joe's latest
> changes ip_vs_ftp.c used %d,%d,%d,%d.

I submitted a couple of patches that should help.

o eventually remove NIPQUAD and NIPQUAD_FMT
o consolidate the 2 netfilter "%u,%u,%u,%u" uses
to a single function

Simon Horman

unread,
Jan 7, 2010, 9:50:02 PM1/7/10
to
On Thu, Jan 07, 2010 at 05:51:48PM -0800, Joe Perches wrote:
> On Fri, 2010-01-08 at 11:08 +1100, Simon Horman wrote:
> > In the vein of this, would it be worth adding some modifier to %i4 to
> > print addresses for ftp helpers? That is, %u,%u,%u,%u. I think
> > there are currently two users of that format string after Joe's latest
> > round of updates.
>
> I think not. I think the comma separated uses
> are unusual enough to not support in lib/vsprintf.

Sounds reasonable.

Andrew Morton

unread,
Jan 19, 2010, 6:10:02 AM1/19/10
to
On Thu, 07 Jan 2010 10:23:45 -0800 Joe Perches <j...@perches.com> wrote:

> Adds 56 bytes to object size

You might want to consider making some of the net-specific code in
vsprintf.c go away if CONFIG_NET=n.

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