linux/lib/vsprintf.c, branch v2.6.25

lib/vsprintf.c: fix bug omitting minus sign of numbers (module_param)

2008-02-24T01:12:14Z

lib/vsprintf.c: Fix bug omitting minus sign of numbers (module_param) Signed-off-by: Hoang-Nam Nguyen Cc: Yi Yang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

x86: trivial printk optimizations

2008-02-09T22:24:09Z

In arch/x86/boot/printf.c gets rid of unused tail of digits: const char *digits = "0123456789abcdefghijklmnopqrstuvwxyz"; (we are using 0-9a-f only) Uses smaller/faster lowercasing (by ORing with 0x20) if we know that we work on numbers/digits. Makes strtoul smaller, and also we are getting rid of static const char small_digits[] = "0123456789abcdefx"; static const char large_digits[] = "0123456789ABCDEFX"; since this works equally well: static const char digits[16] = "0123456789ABCDEF"; Size savings: $ size vmlinux.org vmlinux text data bss dec hex filename 877320 112252 90112 1079684 107984 vmlinux.org 877048 112252 90112 1079412 107874 vmlinux It may be also a tiny bit faster because code has less branches now, but I doubt it is measurable. [ hugh@veritas.com: uppercase pointers fix ] Signed-off-by: Denys Vlasenko Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner

Add new string functions strict_strto* and convert kernel params to use them

2008-02-08T17:22:41Z

Currently, for every sysfs node, the callers will be responsible for implementing store operation, so many many callers are doing duplicate things to validate input, they have the same mistakes because they are calling simple_strtol/ul/ll/uul, especially for module params, they are just numeric, but you can echo such values as 0x1234xxx, 07777888 and 1234aaa, for these cases, module params store operation just ignores succesive invalid char and converts prefix part to a numeric although input is acctually invalid. This patch tries to fix the aforementioned issues and implements strict_strtox serial functions, kernel/params.c uses them to strictly validate input, so module params will reject such values as 0x1234xxxx and returns an error: write error: Invalid argument Any modules which export numeric sysfs node can use strict_strtox instead of simple_strtox to reject any invalid input. Here are some test results: Before applying this patch: [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# echo 0x1000 > /sys/module/e1000/parameters/copybreak [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# echo 0x1000g > /sys/module/e1000/parameters/copybreak [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# echo 0x1000gggggggg > /sys/module/e1000/parameters/copybreak [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# echo 010000 > /sys/module/e1000/parameters/copybreak [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# echo 0100008 > /sys/module/e1000/parameters/copybreak [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# echo 010000aaaaa > /sys/module/e1000/parameters/copybreak [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# After applying this patch: [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# echo 0x1000 > /sys/module/e1000/parameters/copybreak [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# echo 0x1000g > /sys/module/e1000/parameters/copybreak -bash: echo: write error: Invalid argument [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# echo 0x1000gggggggg > /sys/module/e1000/parameters/copybreak -bash: echo: write error: Invalid argument [root@yangyi-dev /]# echo 010000 > /sys/module/e1000/parameters/copybreak [root@yangyi-dev /]# echo 0100008 > /sys/module/e1000/parameters/copybreak -bash: echo: write error: Invalid argument [root@yangyi-dev /]# echo 010000aaaaa > /sys/module/e1000/parameters/copybreak -bash: echo: write error: Invalid argument [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# echo -n 4096 > /sys/module/e1000/parameters/copybreak [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak 4096 [root@yangyi-dev /]# [akpm@linux-foundation.org: fix compiler warnings] [akpm@linux-foundation.org: fix off-by-one found by tiwai@suse.de] Signed-off-by: Yi Yang Cc: Greg KH Cc: "Randy.Dunlap" Cc: Takashi Iwai Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib: move kasprintf to a separate file

2007-07-31T22:39:39Z

kasprintf pulls in kmalloc which proved to be fatal for at least bootimage target on alpha. Move it to a separate file so only users of kasprintf are exposed to the dependency on kmalloc. Signed-off-by: Sam Ravnborg Cc: Jeremy Fitzhardinge Cc: Meelis Roos Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Jay Estabrook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

vsprintf.c: optimizing, part 2: base 10 conversion speedup, v2

2007-07-16T16:05:52Z

Optimize integer-to-string conversion in vsprintf.c for base 10. This is by far the most used conversion, and in some use cases it impacts performance. For example, top reads /proc/$PID/stat for every process, and with 4000 processes decimal conversion alone takes noticeable time. Using code from http://www.cs.uiowa.edu/~jones/bcd/decimal.html (with permission from the author, Douglas W. Jones) binary-to-decimal-string conversion is done in groups of five digits at once, using only additions/subtractions/shifts (with -O2; -Os throws in some multiply instructions). On i386 arch gcc 4.1.2 -O2 generates ~500 bytes of code. This patch is run tested. Userspace benchmark/test is also attached. I tested it on PIII and AMD64 and new code is generally ~2.5 times faster. On AMD64: # ./vsprintf_verify-O2 Original decimal conv: .......... 151 ns per iteration Patched decimal conv: .......... 62 ns per iteration Testing correctness 12895992590592 ok... [Ctrl-C] # ./vsprintf_verify-O2 Original decimal conv: .......... 151 ns per iteration Patched decimal conv: .......... 62 ns per iteration Testing correctness 26025406464 ok... [Ctrl-C] More realistic test: top from busybox project was modified to report how many us it took to scan /proc (this does not account any processing done after that, like sorting process list), and then I test it with 4000 processes: #!/bin/sh i=4000 while test $i != 0; do sleep 30 & let i-- done busybox top -b -n3 >/dev/null on unpatched kernel: top: 4120 processes took 102864 microseconds to scan top: 4120 processes took 91757 microseconds to scan top: 4120 processes took 92517 microseconds to scan top: 4120 processes took 92581 microseconds to scan on patched kernel: top: 4120 processes took 75460 microseconds to scan top: 4120 processes took 66451 microseconds to scan top: 4120 processes took 67267 microseconds to scan top: 4120 processes took 67618 microseconds to scan The speedup comes from much faster generation of /proc/PID/stat by sprintf() calls inside the kernel. Signed-off-by: Douglas W Jones Signed-off-by: Denys Vlasenko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

vsprintf.c: optimizing, part 1 (easy and obvious stuff)

2007-07-16T16:05:52Z

* There is no point in having full "0...9a...z" constant vector, if we use only "0...9a...f" (and "x" for "0x"). * Post-decrement usually needs a few more instructions, so use pre decrement instead where makes sense: - while (i < precision--) { + while (i <= --precision) { * if base != 10 (=> base 8 or 16), we can avoid using division in a loop and use mask/shift, obtaining much faster conversion. (More complex optimization for base 10 case is in the second patch). Overall, size vsprintf.o shows ~80 bytes smaller text section with this patch applied. Signed-off-by: Douglas W Jones Signed-off-by: Denys Vlasenko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fix sscanf %n match at end of input string

2007-05-08T18:15:05Z

I was playing with some code that sometimes got a string where a %n match should have been done where the input string ended, for example like this: sscanf("abc123", "abc%d%n", &a, &n); /* doesn't work */ sscanf("abc123a", "abc%d%n", &a, &n); /* works */ However, the scanf function in the kernel doesn't convert the %n in that case because it has already matched the complete input after %d and just completely stops matching then. This patch fixes that. [akpm@linux-foundation.org: cleanups] Signed-off-by: Johannes Berg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Add kvasprintf()

2007-04-30T23:40:40Z

Add a kvasprintf() function to complement kasprintf(). No in-tree users yet, but I have some coming up. [akpm@linux-foundation.org: EXPORT it] Signed-off-by: Jeremy Fitzhardinge Cc: Andrew Morton Cc: Keir Fraser Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] scnprintf(): fix a comment

2007-02-12T17:48:28Z

The return value of scnprintf() never exceeds @size. Signed-off-by: Martin Peschke Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] Numerous fixes to kernel-doc info in source files.

2007-02-11T18:51:32Z

A variety of (mostly) innocuous fixes to the embedded kernel-doc content in source files, including: * make multi-line initial descriptions single line * denote some function names, constants and structs as such * change erroneous opening '/*' to '/**' in a few places * reword some text for clarity Signed-off-by: Robert P. J. Day Cc: "Randy.Dunlap" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds