user/sven/linux.git/include/linux/string.h, branch v4.1.15

mm/util: add kstrdup_const

2015-02-14T05:21:35Z

kstrdup() is often used to duplicate strings where neither source neither destination will be ever modified. In such case we can just reuse the source instead of duplicating it. The problem is that we must be sure that the source is non-modifiable and its life-time is long enough. I suspect the good candidates for such strings are strings located in kernel .rodata section, they cannot be modifed because the section is read-only and their life-time is equal to kernel life-time. This small patchset proposes alternative version of kstrdup - kstrdup_const, which returns source string if it is located in .rodata otherwise it fallbacks to kstrdup. To verify if the source is in .rodata function checks if the address is between sentinels __start_rodata, __end_rodata. I guess it should work with all architectures. The main patch is accompanied by four patches constifying kstrdup for cases where situtation described above happens frequently. I have tested the patchset on mobile platform (exynos4210-trats) and it saves 3272 string allocations. Since minimal allocation is 32 or 64 bytes depending on Kconfig options the patchset saves respectively about 100KB or 200KB of memory. Stats from tested platform show that the main offender is sysfs: By caller: 2260 __kernfs_new_node 631 clk_register+0xc8/0x1b8 318 clk_register+0x34/0x1b8 51 kmem_cache_create 12 alloc_vfsmnt By string (with count >= 5): 883 power 876 subsystem 135 parameters 132 device 61 iommu_group ... This patch (of 5): Add an alternative version of kstrdup which returns pointer to constant char array. The function checks if input string is in persistent and read-only memory section, if yes it returns the input string, otherwise it fallbacks to kstrdup. kstrdup_const is accompanied by kfree_const performing conditional memory deallocation of the string. Signed-off-by: Andrzej Hajda Cc: Marek Szyprowski Cc: Kyungmin Park Cc: Mike Turquette Cc: Alexander Viro Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Tejun Heo Cc: Greg KH Cc: Geert Uytterhoeven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/string.c: remove strnicmp()

2015-02-13T02:54:14Z

Now that all in-tree users of strnicmp have been converted to strncasecmp, the wrapper can be removed. Signed-off-by: Rasmus Villemoes Cc: David Howells Cc: Heiko Carstens Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

2014-10-24T19:33:32Z

Pull /dev/random updates from Ted Ts'o: "This adds a memzero_explicit() call which is guaranteed not to be optimized away by GCC. This is important when we are wiping cryptographically sensitive material" * tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random: crypto: memzero_explicit - make sure to clear out sensitive data random: add and use memzero_explicit() for clearing data

random: add and use memzero_explicit() for clearing data

2014-10-17T15:37:29Z

zatimend has reported that in his environment (3.16/gcc4.8.3/corei7) memset() calls which clear out sensitive data in extract_{buf,entropy, entropy_user}() in random driver are being optimized away by gcc. Add a helper memzero_explicit() (similarly as explicit_bzero() variants) that can be used in such cases where a variable with sensitive data is being cleared out in the end. Other use cases might also be in crypto code. [ I have put this into lib/string.c though, as it's always built-in and doesn't need any dependencies then. ] Fixes kernel bugzilla: 82041 Reported-by: zatimend@hotmail.co.uk Signed-off-by: Daniel Borkmann Acked-by: Hannes Frederic Sowa Cc: Alexey Dobriyan Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org

lib: string: Make all calls to strnicmp into calls to strncasecmp

2014-10-14T00:18:23Z

The previous patch made strnicmp into a wrapper for strncasecmp. This patch makes all in-tree users of strnicmp call strncasecmp directly, while still making sure that the strnicmp symbol can be used by out-of-tree modules. It should be considered a temporary hack until all in-tree callers have been converted. Signed-off-by: Rasmus Villemoes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib: add glibc style strchrnul() variant

2014-05-23T02:23:27Z

The strchrnul() variant helpfully returns a the end of the string instead of a NULL if the requested character is not found. This can simplify string parsing code since it doesn't need to expicitly check for a NULL return. If a valid string pointer is passed in, then a valid null terminated string will always come back out. Signed-off-by: Grant Likely

string: introduce helper to get base file name from given path

2012-12-18T01:15:17Z

There are several places in the kernel that use functionality like basename(3) with the exception: in case of '/foo/bar/' we expect to get an empty string. Let's do it common helper for them. Signed-off-by: Andy Shevchenko Cc: Jason Baron Cc: YAMANE Toshiaki Cc: Greg Kroah-Hartman Cc: Steven Rostedt Cc: Frederic Weisbecker Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

UAPI: (Scripted) Disintegrate include/linux

2012-10-13T09:46:48Z

Signed-off-by: David Howells Acked-by: Arnd Bergmann Acked-by: Thomas Gleixner Acked-by: Michael Kerrisk Acked-by: Paul E. McKenney Acked-by: Dave Jones

string: do not export memweight() to userspace

2012-08-21T23:45:03Z

Fix the following warning: usr/include/linux/string.h:8: userspace cannot reference function or variable defined in the kernel Signed-off-by: WANG Cong Acked-by: Akinobu Mita Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

string: introduce memweight()

2012-07-31T00:25:16Z

memweight() is the function that counts the total number of bits set in memory area. Unlike bitmap_weight(), memweight() takes pointer and size in bytes to specify a memory area which does not need to be aligned to long-word boundary. [akpm@linux-foundation.org: rename `w' to `ret'] Signed-off-by: Akinobu Mita Cc: Anders Larsen Cc: Alasdair Kergon Cc: Laurent Pinchart Cc: Mark Fasheh Cc: Joel Becker Cc: Jan Kara Cc: Andreas Dilger Cc: "Theodore Ts'o" Cc: Matthew Wilcox Cc: Mauro Carvalho Chehab Cc: Tony Luck Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds