From 074e61ec3751da9ab88ee66d3818574556c03489 Mon Sep 17 00:00:00 2001 From: James Morris Date: Wed, 10 Nov 2010 09:01:31 +1100 Subject: kernel: add roundup() code comment from akpm Add roundup() code comment from akpm. Signed-off-by: Andrew Morton Signed-off-by: James Morris --- include/linux/kernel.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index b526947bdf48..3f648d204c37 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -58,6 +58,8 @@ extern const char linux_proc_banner[]; #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f)) #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d)) + +/* The `const' in roundup() prevents gcc-3.3 from calling __divdi3 */ #define roundup(x, y) ( \ { \ const typeof(y) __y = y; \ -- cgit v1.2.3 From dc88e46029486ed475c71fe1bb696d39511ac8fe Mon Sep 17 00:00:00 2001 From: Mimi Zohar Date: Tue, 23 Nov 2010 17:50:31 -0500 Subject: lib: hex2bin converts ascii hexadecimal string to binary Similar to the kgdb_hex2mem() code, hex2bin converts a string to binary using the hex_to_bin() library call. Changelog: - Replace parameter names with src/dst (based on David Howell's comment) - Add 'const' where needed (based on David Howell's comment) - Replace int with size_t (based on David Howell's comment) Signed-off-by: Mimi Zohar Acked-by: Serge E. Hallyn Acked-by: David Howells Signed-off-by: James Morris --- include/linux/kernel.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index a35b4f7332f0..d0fbc043de60 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -265,6 +265,7 @@ static inline char *pack_hex_byte(char *buf, u8 byte) } extern int hex_to_bin(char ch); +extern void hex2bin(u8 *dst, const char *src, size_t count); /* * General tracing related utility functions - trace_printk(), -- cgit v1.2.3 From 71a9048448de302d1e968f336de01060d02fae71 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Wed, 12 Jan 2011 16:59:35 -0800 Subject: include/linux/kernel.h: abs(): fix handling of 32-bit unsigneds on 64-bit Michal reports: In the framebuffer subsystem the abs() macro is often used as a part of the calculation of a Manhattan metric, which in turn is used as a measure of similarity between video modes. The arguments of abs() are sometimes unsigned numbers. This worked fine until commit a49c59c0 ("Make sure the value in abs() does not get truncated if it is greater than 2^32:) , which changed the definition of abs() to prevent truncation. As a result of this change, in the following piece of code: u32 a = 0, b = 1; u32 c = abs(a - b); 'c' will end up with a value of 0xffffffff instead of the expected 0x1. A problem caused by this change and visible by the end user is that framebuffer drivers relying on functions from modedb.c will fail to find high resolution video modes similar to that explicitly requested by the user if an exact match cannot be found (see e.g. Fix this by special-casing `long' types within abs(). This patch reduces x86_64 code size a bit - drivers/video/uvesafb.o shrunk by 15 bytes, presumably because it is doing abs() on 4-byte quantities, and expanding those to 8-byte longs adds code. testcase: #define oldabs(x) ({ \ long __x = (x); \ (__x < 0) ? -__x : __x; \ }) #define newabs(x) ({ \ long ret; \ if (sizeof(x) == sizeof(long)) { \ long __x = (x); \ ret = (__x < 0) ? -__x : __x; \ } else { \ int __x = (x); \ ret = (__x < 0) ? -__x : __x; \ } \ ret; \ }) typedef unsigned int u32; main() { u32 a = 0; u32 b = 1; u32 oldc = oldabs(a - b); u32 newc = newabs(a - b); printf("%u %u\n", oldc, newc); } akpm:/home/akpm> gcc t.c akpm:/home/akpm> ./a.out 4294967295 1 Reported-by: Michal Januszewski Cc: Rolf Eike Beer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index d0fbc043de60..57dac7022b63 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -143,9 +143,22 @@ extern int _cond_resched(void); #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0) -#define abs(x) ({ \ - long __x = (x); \ - (__x < 0) ? -__x : __x; \ +/* + * abs() handles unsigned and signed longs, ints, shorts and chars. For all + * input types abs() returns a signed long. + * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64() + * for those. + */ +#define abs(x) ({ \ + long ret; \ + if (sizeof(x) == sizeof(long)) { \ + long __x = (x); \ + ret = (__x < 0) ? -__x : __x; \ + } else { \ + int __x = (x); \ + ret = (__x < 0) ? -__x : __x; \ + } \ + ret; \ }) #define abs64(x) ({ \ -- cgit v1.2.3 From 3e7d344970673c5334cf7b5bb27c8c0942b06126 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Thu, 13 Jan 2011 15:45:56 -0800 Subject: mm: vmscan: reclaim order-0 and use compaction instead of lumpy reclaim Lumpy reclaim is disruptive. It reclaims a large number of pages and ignores the age of the pages it reclaims. This can incur significant stalls and potentially increase the number of major faults. Compaction has reached the point where it is considered reasonably stable (meaning it has passed a lot of testing) and is a potential candidate for displacing lumpy reclaim. This patch introduces an alternative to lumpy reclaim whe compaction is available called reclaim/compaction. The basic operation is very simple - instead of selecting a contiguous range of pages to reclaim, a number of order-0 pages are reclaimed and then compaction is later by either kswapd (compact_zone_order()) or direct compaction (__alloc_pages_direct_compact()). [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: use conventional task_struct naming] Signed-off-by: Mel Gorman Cc: Andrea Arcangeli Cc: KOSAKI Motohiro Cc: Rik van Riel Acked-by: Johannes Weiner Cc: Andy Whitcroft Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 57dac7022b63..5a9d9059520b 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -600,6 +600,13 @@ struct sysinfo { #define NUMA_BUILD 0 #endif +/* This helps us avoid #ifdef CONFIG_COMPACTION */ +#ifdef CONFIG_COMPACTION +#define COMPACTION_BUILD 1 +#else +#define COMPACTION_BUILD 0 +#endif + /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */ #ifdef CONFIG_FTRACE_MCOUNT_RECORD # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD -- cgit v1.2.3