From af3cd13501eb04ca61d017ff4406f1cbffafdc04 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Thu, 12 Feb 2015 15:02:15 -0800 Subject: lib/string.c: remove strnicmp() 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 --- include/linux/string.h | 3 --- 1 file changed, 3 deletions(-) (limited to 'include/linux/string.h') diff --git a/include/linux/string.h b/include/linux/string.h index 2e22a2e58f3a..b9bc9a5d9e21 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -40,9 +40,6 @@ extern int strcmp(const char *,const char *); #ifndef __HAVE_ARCH_STRNCMP extern int strncmp(const char *,const char *,__kernel_size_t); #endif -#ifndef __HAVE_ARCH_STRNICMP -#define strnicmp strncasecmp -#endif #ifndef __HAVE_ARCH_STRCASECMP extern int strcasecmp(const char *s1, const char *s2); #endif -- cgit v1.2.3 From a4bb1e43e22d3cade8f942fc6f95920248eb2fd0 Mon Sep 17 00:00:00 2001 From: Andrzej Hajda Date: Fri, 13 Feb 2015 14:36:24 -0800 Subject: mm/util: add kstrdup_const 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 --- include/linux/string.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/string.h') diff --git a/include/linux/string.h b/include/linux/string.h index b9bc9a5d9e21..e40099e585c9 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -112,7 +112,10 @@ extern void * memchr(const void *,int,__kernel_size_t); #endif void *memchr_inv(const void *s, int c, size_t n); +extern void kfree_const(const void *x); + extern char *kstrdup(const char *s, gfp_t gfp); +extern const char *kstrdup_const(const char *s, gfp_t gfp); extern char *kstrndup(const char *s, size_t len, gfp_t gfp); extern void *kmemdup(const void *src, size_t len, gfp_t gfp); -- cgit v1.2.3