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authorAkinobu Mita <akinobu.mita@gmail.com>2011-10-31 17:08:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-10-31 17:30:47 -0700
commit798248206b59acc6e1238c778281419c041891a7 (patch)
treeff8564431367b442b18bca4a0a9732e5799e2391
parent77311139f364d7f71fc9ba88f59fd90e60205007 (diff)
lib/string.c: introduce memchr_inv()
memchr_inv() is mainly used to check whether the whole buffer is filled with just a specified byte. The function name and prototype are stolen from logfs and the implementation is from SLUB. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Acked-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@kernel.org> Cc: Matt Mackall <mpm@selenic.com> Acked-by: Joern Engel <joern@logfs.org> Cc: Marcin Slusarz <marcin.slusarz@gmail.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/logfs/logfs.h1
-rw-r--r--fs/logfs/super.c22
-rw-r--r--include/linux/string.h1
-rw-r--r--lib/string.c54
-rw-r--r--mm/slub.c47
5 files changed, 57 insertions, 68 deletions
diff --git a/fs/logfs/logfs.h b/fs/logfs/logfs.h
index f22d108bfa5d..398ecff6e548 100644
--- a/fs/logfs/logfs.h
+++ b/fs/logfs/logfs.h
@@ -618,7 +618,6 @@ static inline int logfs_buf_recover(struct logfs_area *area, u64 ofs,
struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index);
void emergency_read_end(struct page *page);
void logfs_crash_dump(struct super_block *sb);
-void *memchr_inv(const void *s, int c, size_t n);
int logfs_statfs(struct dentry *dentry, struct kstatfs *stats);
int logfs_check_ds(struct logfs_disk_super *ds);
int logfs_write_sb(struct super_block *sb);
diff --git a/fs/logfs/super.c b/fs/logfs/super.c
index ce03a182c771..f2697e4df109 100644
--- a/fs/logfs/super.c
+++ b/fs/logfs/super.c
@@ -91,28 +91,6 @@ void logfs_crash_dump(struct super_block *sb)
}
/*
- * TODO: move to lib/string.c
- */
-/**
- * memchr_inv - Find a character in an area of memory.
- * @s: The memory area
- * @c: The byte to search for
- * @n: The size of the area.
- *
- * returns the address of the first character other than @c, or %NULL
- * if the whole buffer contains just @c.
- */
-void *memchr_inv(const void *s, int c, size_t n)
-{
- const unsigned char *p = s;
- while (n-- != 0)
- if ((unsigned char)c != *p++)
- return (void *)(p - 1);
-
- return NULL;
-}
-
-/*
* FIXME: There should be a reserve for root, similar to ext2.
*/
int logfs_statfs(struct dentry *dentry, struct kstatfs *stats)
diff --git a/include/linux/string.h b/include/linux/string.h
index a176db2f2c85..e033564f10ba 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -114,6 +114,7 @@ extern int memcmp(const void *,const void *,__kernel_size_t);
#ifndef __HAVE_ARCH_MEMCHR
extern void * memchr(const void *,int,__kernel_size_t);
#endif
+void *memchr_inv(const void *s, int c, size_t n);
extern char *kstrdup(const char *s, gfp_t gfp);
extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
diff --git a/lib/string.c b/lib/string.c
index 01fad9b203e1..11df54325fb8 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -756,3 +756,57 @@ void *memchr(const void *s, int c, size_t n)
}
EXPORT_SYMBOL(memchr);
#endif
+
+static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
+{
+ while (bytes) {
+ if (*start != value)
+ return (void *)start;
+ start++;
+ bytes--;
+ }
+ return NULL;
+}
+
+/**
+ * memchr_inv - Find an unmatching character in an area of memory.
+ * @start: The memory area
+ * @c: Find a character other than c
+ * @bytes: The size of the area.
+ *
+ * returns the address of the first character other than @c, or %NULL
+ * if the whole buffer contains just @c.
+ */
+void *memchr_inv(const void *start, int c, size_t bytes)
+{
+ u8 value = c;
+ u64 value64;
+ unsigned int words, prefix;
+
+ if (bytes <= 16)
+ return check_bytes8(start, value, bytes);
+
+ value64 = value | value << 8 | value << 16 | value << 24;
+ value64 = (value64 & 0xffffffff) | value64 << 32;
+ prefix = 8 - ((unsigned long)start) % 8;
+
+ if (prefix) {
+ u8 *r = check_bytes8(start, value, prefix);
+ if (r)
+ return r;
+ start += prefix;
+ bytes -= prefix;
+ }
+
+ words = bytes / 8;
+
+ while (words) {
+ if (*(u64 *)start != value64)
+ return check_bytes8(start, value, 8);
+ start += 8;
+ words--;
+ }
+
+ return check_bytes8(start, value, bytes % 8);
+}
+EXPORT_SYMBOL(memchr_inv);
diff --git a/mm/slub.c b/mm/slub.c
index 95215aa6a75e..7d2a996c307e 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -655,49 +655,6 @@ static void init_object(struct kmem_cache *s, void *object, u8 val)
memset(p + s->objsize, val, s->inuse - s->objsize);
}
-static u8 *check_bytes8(u8 *start, u8 value, unsigned int bytes)
-{
- while (bytes) {
- if (*start != value)
- return start;
- start++;
- bytes--;
- }
- return NULL;
-}
-
-static u8 *check_bytes(u8 *start, u8 value, unsigned int bytes)
-{
- u64 value64;
- unsigned int words, prefix;
-
- if (bytes <= 16)
- return check_bytes8(start, value, bytes);
-
- value64 = value | value << 8 | value << 16 | value << 24;
- value64 = (value64 & 0xffffffff) | value64 << 32;
- prefix = 8 - ((unsigned long)start) % 8;
-
- if (prefix) {
- u8 *r = check_bytes8(start, value, prefix);
- if (r)
- return r;
- start += prefix;
- bytes -= prefix;
- }
-
- words = bytes / 8;
-
- while (words) {
- if (*(u64 *)start != value64)
- return check_bytes8(start, value, 8);
- start += 8;
- words--;
- }
-
- return check_bytes8(start, value, bytes % 8);
-}
-
static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
void *from, void *to)
{
@@ -712,7 +669,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
u8 *fault;
u8 *end;
- fault = check_bytes(start, value, bytes);
+ fault = memchr_inv(start, value, bytes);
if (!fault)
return 1;
@@ -805,7 +762,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
if (!remainder)
return 1;
- fault = check_bytes(end - remainder, POISON_INUSE, remainder);
+ fault = memchr_inv(end - remainder, POISON_INUSE, remainder);
if (!fault)
return 1;
while (end > fault && end[-1] == POISON_INUSE)