| Submitter | Akinobu Mita |
|---|---|
| Date | June 9, 2012, 12:50 a.m. |
| Message ID | <1339203038-13069-1-git-send-email-akinobu.mita@gmail.com> |
| Download | mbox | patch |
| Permalink | /patch/163875/ |
| State | Not Applicable |
| Headers | show |
Comments
On Fri, Jun 8, 2012 at 5:50 PM, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> lib/string.c | 36 ++++++++++++++++++++++++++++++++++++
Is lib/string.c the right place for this? I get a build error on the
ia64 sim_defconfig:
LD arch/ia64/hp/sim/boot/bootloader
It fails because it pulls in lib/lib.a(string.o) to get some
innocuous function like strcpy() ... but it also gets
given memweight() which relies on __bitmap_weight()
which it doesn't have, because it doesn't include lib/built-in.o
(which is where bitmap.o, the definer of __bitmap_weight(), has
been linked).
Moving memweight() to lib/bitmap.c fixes the problem. But it
isn't really clear that it belongs there either. Perhaps it should
be its own file lib/memweight.c that gets included in lib/lib.a?
-Tony
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2012/6/21 Tony Luck <tony.luck@gmail.com>: > On Fri, Jun 8, 2012 at 5:50 PM, Akinobu Mita <akinobu.mita@gmail.com> wrote: >> lib/string.c | 36 ++++++++++++++++++++++++++++++++++++ > > Is lib/string.c the right place for this? I get a build error on the > ia64 sim_defconfig: > > LD arch/ia64/hp/sim/boot/bootloader > > It fails because it pulls in lib/lib.a(string.o) to get some > innocuous function like strcpy() ... but it also gets > given memweight() which relies on __bitmap_weight() > which it doesn't have, because it doesn't include lib/built-in.o > (which is where bitmap.o, the definer of __bitmap_weight(), has > been linked). > > Moving memweight() to lib/bitmap.c fixes the problem. But it > isn't really clear that it belongs there either. Perhaps it should > be its own file lib/memweight.c that gets included in lib/lib.a? I'll fix it by making lib/memweight.c as you suggested. Thanks for your report and suggestion. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Patch
diff --git a/include/linux/string.h b/include/linux/string.h index e033564..ffe0442 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -145,4 +145,7 @@ static inline bool strstarts(const char *str, const char *prefix) return strncmp(str, prefix, strlen(prefix)) == 0; } #endif + +extern size_t memweight(const void *ptr, size_t bytes); + #endif /* _LINUX_STRING_H_ */ diff --git a/lib/string.c b/lib/string.c index e5878de..e467186 100644 --- a/lib/string.c +++ b/lib/string.c @@ -26,6 +26,7 @@ #include <linux/export.h> #include <linux/bug.h> #include <linux/errno.h> +#include <linux/bitmap.h> #ifndef __HAVE_ARCH_STRNICMP /** @@ -824,3 +825,38 @@ void *memchr_inv(const void *start, int c, size_t bytes) return check_bytes8(start, value, bytes % 8); } EXPORT_SYMBOL(memchr_inv); + +/** + * memweight - count the total number of bits set in memory area + * @ptr: pointer to the start of the area + * @bytes: the size of the area + */ +size_t memweight(const void *ptr, size_t bytes) +{ + size_t w = 0; + size_t longs; + const unsigned char *bitmap = ptr; + + for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long); + bytes--, bitmap++) + w += hweight8(*bitmap); + + longs = bytes / sizeof(long); + if (longs) { + BUG_ON(longs >= INT_MAX / BITS_PER_LONG); + w += bitmap_weight((unsigned long *)bitmap, + longs * BITS_PER_LONG); + bytes -= longs * sizeof(long); + bitmap += longs * sizeof(long); + } + /* + * The reason that this last loop is distinct from the preceding + * bitmap_weight() call is to compute 1-bits in the last region smaller + * than sizeof(long) properly on big-endian systems. + */ + for (; bytes > 0; bytes--, bitmap++) + w += hweight8(*bitmap); + + return w; +} +EXPORT_SYMBOL(memweight);
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. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Anders Larsen <al@alarsen.net> Cc: Alasdair Kergon <agk@redhat.com> Cc: dm-devel@redhat.com Cc: linux-fsdevel@vger.kernel.org Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: linux-media@vger.kernel.org Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: ocfs2-devel@oss.oracle.com Cc: Jan Kara <jack@suse.cz> Cc: linux-ext4@vger.kernel.org Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Matthew Wilcox <matthew@wil.cx> --- v3: add comment for the last loop, adviced by Jan Kara v2: simplify memweight(), adviced by Jan Kara include/linux/string.h | 3 +++ lib/string.c | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+), 0 deletions(-)