[PATCH v4 0/7] lib: rework bitmap_parse

[PATCH v4 0/7] lib: rework bitmap_parse

[Yury Norov]

Hi all,

I'm sorry for long delay with re-submission of this series
As Andy mentioned in review for v3, I switched to isxdigit()
where appropriate. I also removed my Marvell's signed-off-by
since I don't work for them anymore.

Thanks,
Yury

On top of next-20190904.

Similarly to recently revisited bitmap_parselist() [1],
bitmap_parse() is ineffective and overcomplicated.  This
series reworks it, aligns its interface with bitmap_parselist()
and makes usage simpler.

The series also adds a test for the function and fixes usage of it
in cpumask_parse() according to new design - drops the calculating
of length of an input string.

bitmap_parse() takes the array of numbers to be put into the map in
the BE order which is reversed to the natural LE order for bitmaps.
For example, to construct bitmap containing a bit on the position 42,
we have to put a line '400,0'. Current implementation reads chunk
one by one from the beginning ('400' before '0') and makes bitmap
shift after each successful parse. It makes the complexity of the
whole process as O(n^2). We can do it in reverse direction ('0'
before '400') and avoid shifting, but it requires reverse parsing
helpers.

Tested on arm64 and BE mips.

v1: https://lkml.org/lkml/2019/4/27/597
v2:
 - strnchrnul() signature and description changed, ifdeffery and
   exporting removed;
 - test split for better demonstration of before/after changes;
 - minor naming and formatting issues fixed.
v3:
  - fix bitmap_clear() misuse.
  - opencode in_str() helper.
  - simplify while() in bitmap_parse()
v4:
  - use isxdigit() where appropriate.
  - clean signed-off-by list.


Yury Norov (7):
  lib/string: add strnchrnul()
  bitops: more BITS_TO_* macros
  lib: add test for bitmap_parse()
  lib: make bitmap_parse_user a wrapper on bitmap_parse
  lib: rework bitmap_parse()
  lib: new testcases for bitmap_parse{_user}
  cpumask: don't calculate length of the input string

 include/linux/bitmap.h       |   8 +-
 include/linux/bitops.h       |   5 +-
 include/linux/cpumask.h      |   4 +-
 include/linux/string.h       |   1 +
 lib/bitmap.c                 | 196 +++++++++++++++++------------------
 lib/string.c                 |  17 +++
 lib/test_bitmap.c            | 102 +++++++++++++++++-
 tools/include/linux/bitops.h |   9 +-
 8 files changed, 225 insertions(+), 117 deletions(-)

-- 
2.20.1

[PATCH 1/7] lib/string: add strnchrnul()

[Yury Norov]

New function works like strchrnul() with a length limited strings.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 include/linux/string.h |  1 +
 lib/string.c           | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/include/linux/string.h b/include/linux/string.h
index 3cf684db4bc6b..cf8f47efeb051 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -107,6 +107,7 @@ extern char * strchr(const char *,int);
 #ifndef __HAVE_ARCH_STRCHRNUL
 extern char * strchrnul(const char *,int);
 #endif
+extern char * strnchrnul(const char *, size_t, int);
 #ifndef __HAVE_ARCH_STRNCHR
 extern char * strnchr(const char *, size_t, int);
 #endif
diff --git a/lib/string.c b/lib/string.c
index cd7a10c192109..75b10363e61f0 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -434,6 +434,23 @@ char *strchrnul(const char *s, int c)
 EXPORT_SYMBOL(strchrnul);
 #endif
 
+/**
+ * strnchrnul - Find and return a character in a length limited string,
+ * or end of string
+ * @s: The string to be searched
+ * @count: The number of characters to be searched
+ * @c: The character to search for
+ *
+ * Returns pointer to the first occurrence of 'c' in s. If c is not found,
+ * then return a pointer to the last character of the string.
+ */
+char *strnchrnul(const char *s, size_t count, int c)
+{
+	while (count-- && *s && *s != (char)c)
+		s++;
+	return (char *)s;
+}
+
 #ifndef __HAVE_ARCH_STRRCHR
 /**
  * strrchr - Find the last occurrence of a character in a string
-- 
2.20.1

[PATCH 2/7] bitops: more BITS_TO_* macros

[Yury Norov]

Introduce BITS_TO_U64, BITS_TO_U32 and BITS_TO_BYTES as they are handy
in the following patches (BITS_TO_U32 specifically). Reimplement tools/
version of the macros according to the kernel implementation.

Also fix indentation for BITS_PER_TYPE definition.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 include/linux/bitops.h       | 5 ++++-
 tools/include/linux/bitops.h | 9 +++++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index cf074bce3eb32..e61c4e6142641 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -4,8 +4,11 @@
 #include <asm/types.h>
 #include <linux/bits.h>
 
-#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
+#define BITS_PER_TYPE(type)	(sizeof(type) * BITS_PER_BYTE)
 #define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
+#define BITS_TO_U64(nr)		DIV_ROUND_UP(nr, BITS_PER_TYPE(u64))
+#define BITS_TO_U32(nr)		DIV_ROUND_UP(nr, BITS_PER_TYPE(u32))
+#define BITS_TO_BYTES(nr)	DIV_ROUND_UP(nr, BITS_PER_TYPE(char))
 
 extern unsigned int __sw_hweight8(unsigned int w);
 extern unsigned int __sw_hweight16(unsigned int w);
diff --git a/tools/include/linux/bitops.h b/tools/include/linux/bitops.h
index 140c8362f1139..5fca38fe1ba83 100644
--- a/tools/include/linux/bitops.h
+++ b/tools/include/linux/bitops.h
@@ -14,10 +14,11 @@
 #include <linux/bits.h>
 #include <linux/compiler.h>
 
-#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
-#define BITS_TO_U64(nr)		DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(u64))
-#define BITS_TO_U32(nr)		DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(u32))
-#define BITS_TO_BYTES(nr)	DIV_ROUND_UP(nr, BITS_PER_BYTE)
+#define BITS_PER_TYPE(type)	(sizeof(type) * BITS_PER_BYTE)
+#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
+#define BITS_TO_U64(nr)		DIV_ROUND_UP(nr, BITS_PER_TYPE(u64))
+#define BITS_TO_U32(nr)		DIV_ROUND_UP(nr, BITS_PER_TYPE(u32))
+#define BITS_TO_BYTES(nr)	DIV_ROUND_UP(nr, BITS_PER_TYPE(char))
 
 extern unsigned int __sw_hweight8(unsigned int w);
 extern unsigned int __sw_hweight16(unsigned int w);
-- 
2.20.1

[PATCH 3/7] lib: add test for bitmap_parse()

[Yury Norov]

The test is derived from bitmap_parselist()
NO_LEN is reserved for use in following patches.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 lib/test_bitmap.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 93 insertions(+), 1 deletion(-)

diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index 51a98f7ee79e6..e306d3da12019 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -206,7 +206,8 @@ static void __init test_copy(void)
 	expect_eq_pbl("0-108,128-1023", bmap2, 1024);
 }
 
-#define PARSE_TIME 0x1
+#define PARSE_TIME	0x1
+#define NO_LEN		0x2
 
 struct test_bitmap_parselist{
 	const int errno;
@@ -329,6 +330,85 @@ static void __init __test_bitmap_parselist(int is_user)
 	}
 }
 
+static const unsigned long parse_test[] __initconst = {
+	BITMAP_FROM_U64(0),
+	BITMAP_FROM_U64(1),
+	BITMAP_FROM_U64(0xdeadbeef),
+	BITMAP_FROM_U64(0x100000000ULL),
+};
+
+static const unsigned long parse_test2[] __initconst = {
+	BITMAP_FROM_U64(0x100000000ULL), BITMAP_FROM_U64(0xdeadbeef),
+	BITMAP_FROM_U64(0x100000000ULL), BITMAP_FROM_U64(0xbaadf00ddeadbeef),
+	BITMAP_FROM_U64(0x100000000ULL), BITMAP_FROM_U64(0x0badf00ddeadbeef),
+};
+
+static const struct test_bitmap_parselist parse_tests[] __initconst = {
+	{0, "0",			&parse_test[0 * step], 32, 0},
+	{0, "1",			&parse_test[1 * step], 32, 0},
+	{0, "deadbeef",			&parse_test[2 * step], 32, 0},
+	{0, "1,0",			&parse_test[3 * step], 33, 0},
+
+	{0, "deadbeef,1,0",		&parse_test2[0 * 2 * step], 96, 0},
+	{0, "baadf00d,deadbeef,1,0",	&parse_test2[1 * 2 * step], 128, 0},
+	{0, "badf00d,deadbeef,1,0",	&parse_test2[2 * 2 * step], 124, 0},
+
+	{-EINVAL,    "goodfood,deadbeef,1,0",	NULL, 128, 0},
+	{-EOVERFLOW, "3,0",			NULL, 33, 0},
+	{-EOVERFLOW, "123badf00d,deadbeef,1,0",	NULL, 128, 0},
+	{-EOVERFLOW, "badf00d,deadbeef,1,0",	NULL, 90, 0},
+	{-EOVERFLOW, "fbadf00d,deadbeef,1,0",	NULL, 95, 0},
+	{-EOVERFLOW, "badf00d,deadbeef,1,0",	NULL, 100, 0},
+};
+
+static void __init __test_bitmap_parse(int is_user)
+{
+	int i;
+	int err;
+	ktime_t time;
+	DECLARE_BITMAP(bmap, 2048);
+	char *mode = is_user ? "_user"  : "";
+
+	for (i = 0; i < ARRAY_SIZE(parse_tests); i++) {
+		struct test_bitmap_parselist test = parse_tests[i];
+
+		if (is_user) {
+			size_t len = strlen(test.in);
+			mm_segment_t orig_fs = get_fs();
+
+			set_fs(KERNEL_DS);
+			time = ktime_get();
+			err = bitmap_parse_user(test.in, len, bmap, test.nbits);
+			time = ktime_get() - time;
+			set_fs(orig_fs);
+		} else {
+			size_t len = test.flags & NO_LEN ?
+				UINT_MAX : strlen(test.in);
+			time = ktime_get();
+			err = bitmap_parse(test.in, len, bmap, test.nbits);
+			time = ktime_get() - time;
+		}
+
+		if (err != test.errno) {
+			pr_err("parse%s: %d: input is %s, errno is %d, expected %d\n",
+					mode, i, test.in, err, test.errno);
+			continue;
+		}
+
+		if (!err && test.expected
+			 && !__bitmap_equal(bmap, test.expected, test.nbits)) {
+			pr_err("parse%s: %d: input is %s, result is 0x%lx, expected 0x%lx\n",
+					mode, i, test.in, bmap[0],
+					*test.expected);
+			continue;
+		}
+
+		if (test.flags & PARSE_TIME)
+			pr_err("parse%s: %d: input is '%s' OK, Time: %llu\n",
+					mode, i, test.in, time);
+	}
+}
+
 static void __init test_bitmap_parselist(void)
 {
 	__test_bitmap_parselist(0);
@@ -339,6 +419,16 @@ static void __init test_bitmap_parselist_user(void)
 	__test_bitmap_parselist(1);
 }
 
+static void __init test_bitmap_parse(void)
+{
+	__test_bitmap_parse(0);
+}
+
+static void __init test_bitmap_parse_user(void)
+{
+	__test_bitmap_parse(1);
+}
+
 #define EXP_BYTES	(sizeof(exp) * 8)
 
 static void __init test_bitmap_arr32(void)
@@ -410,6 +500,8 @@ static void __init selftest(void)
 	test_fill_set();
 	test_copy();
 	test_bitmap_arr32();
+	test_bitmap_parse();
+	test_bitmap_parse_user();
 	test_bitmap_parselist();
 	test_bitmap_parselist_user();
 	test_mem_optimisations();
-- 
2.20.1

[PATCH 4/7] lib: make bitmap_parse_user a wrapper on bitmap_parse

[Yury Norov]

Currently we parse user data byte after byte which leads to
overcomplicating of parsing algorithm. There are no performance
critical users of bitmap_parse_user(), and so we can duplicate
user data to kernel buffer and simply call bitmap_parselist().
This rework lets us unify and simplify bitmap_parse() and
bitmap_parse_user(), which is done in the following patch.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 lib/bitmap.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index f9e834841e941..51ee14577166e 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -452,22 +452,22 @@ EXPORT_SYMBOL(__bitmap_parse);
  *    then it must be terminated with a \0.
  * @maskp: pointer to bitmap array that will contain result.
  * @nmaskbits: size of bitmap, in bits.
- *
- * Wrapper for __bitmap_parse(), providing it with user buffer.
- *
- * We cannot have this as an inline function in bitmap.h because it needs
- * linux/uaccess.h to get the access_ok() declaration and this causes
- * cyclic dependencies.
  */
 int bitmap_parse_user(const char __user *ubuf,
 			unsigned int ulen, unsigned long *maskp,
 			int nmaskbits)
 {
-	if (!access_ok(ubuf, ulen))
-		return -EFAULT;
-	return __bitmap_parse((const char __force *)ubuf,
-				ulen, 1, maskp, nmaskbits);
+	char *buf;
+	int ret;
 
+	buf = memdup_user_nul(ubuf, ulen);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	ret = bitmap_parse(buf, ulen, maskp, nmaskbits);
+
+	kfree(buf);
+	return ret;
 }
 EXPORT_SYMBOL(bitmap_parse_user);
 
-- 
2.20.1

[PATCH 5/7] lib: rework bitmap_parse()

[Yury Norov]

bitmap_parse() is ineffective and full of opaque variables and opencoded
parts. It leads to hard understanding and usage of it. This rework
includes:
 - remove bitmap_shift_left() call from the cycle. Now it makes the
   complexity of the algorithm as O(nbits^2). In the suggested approach
   the input string is parsed in reverse direction, so no shifts needed;
 - relax requirement on a single comma and no white spaces between chunks.
   It is considered useful in scripting, and it aligns with
   bitmap_parselist();
 - split bitmap_parse() to small readable helpers;
 - make an explicit calculation of the end of input line at the
   beginning, so users of the bitmap_parse() won't bother doing this.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 include/linux/bitmap.h |   8 +-
 lib/bitmap.c           | 178 ++++++++++++++++++++---------------------
 2 files changed, 87 insertions(+), 99 deletions(-)

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 90528f12bdfa6..bad43c4a5eaca 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -176,7 +176,7 @@ bitmap_find_next_zero_area(unsigned long *map,
 					      align_mask, 0);
 }
 
-extern int __bitmap_parse(const char *buf, unsigned int buflen, int is_user,
+extern int bitmap_parse(const char *buf, unsigned int buflen,
 			unsigned long *dst, int nbits);
 extern int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
 			unsigned long *dst, int nbits);
@@ -431,12 +431,6 @@ static inline void bitmap_shift_left(unsigned long *dst, const unsigned long *sr
 		__bitmap_shift_left(dst, src, shift, nbits);
 }
 
-static inline int bitmap_parse(const char *buf, unsigned int buflen,
-			unsigned long *maskp, int nmaskbits)
-{
-	return __bitmap_parse(buf, buflen, 0, maskp, nmaskbits);
-}
-
 /**
  * BITMAP_FROM_U64() - Represent u64 value in the format suitable for bitmap.
  * @n: u64 value
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 51ee14577166e..008f53714950a 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -353,97 +353,6 @@ EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
  * second version by Paul Jackson, third by Joe Korty.
  */
 
-#define CHUNKSZ				32
-#define nbits_to_hold_value(val)	fls(val)
-#define BASEDEC 10		/* fancier cpuset lists input in decimal */
-
-/**
- * __bitmap_parse - convert an ASCII hex string into a bitmap.
- * @buf: pointer to buffer containing string.
- * @buflen: buffer size in bytes.  If string is smaller than this
- *    then it must be terminated with a \0.
- * @is_user: location of buffer, 0 indicates kernel space
- * @maskp: pointer to bitmap array that will contain result.
- * @nmaskbits: size of bitmap, in bits.
- *
- * Commas group hex digits into chunks.  Each chunk defines exactly 32
- * bits of the resultant bitmask.  No chunk may specify a value larger
- * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
- * then leading 0-bits are prepended.  %-EINVAL is returned for illegal
- * characters and for grouping errors such as "1,,5", ",44", "," and "".
- * Leading and trailing whitespace accepted, but not embedded whitespace.
- */
-int __bitmap_parse(const char *buf, unsigned int buflen,
-		int is_user, unsigned long *maskp,
-		int nmaskbits)
-{
-	int c, old_c, totaldigits, ndigits, nchunks, nbits;
-	u32 chunk;
-	const char __user __force *ubuf = (const char __user __force *)buf;
-
-	bitmap_zero(maskp, nmaskbits);
-
-	nchunks = nbits = totaldigits = c = 0;
-	do {
-		chunk = 0;
-		ndigits = totaldigits;
-
-		/* Get the next chunk of the bitmap */
-		while (buflen) {
-			old_c = c;
-			if (is_user) {
-				if (__get_user(c, ubuf++))
-					return -EFAULT;
-			}
-			else
-				c = *buf++;
-			buflen--;
-			if (isspace(c))
-				continue;
-
-			/*
-			 * If the last character was a space and the current
-			 * character isn't '\0', we've got embedded whitespace.
-			 * This is a no-no, so throw an error.
-			 */
-			if (totaldigits && c && isspace(old_c))
-				return -EINVAL;
-
-			/* A '\0' or a ',' signal the end of the chunk */
-			if (c == '\0' || c == ',')
-				break;
-
-			if (!isxdigit(c))
-				return -EINVAL;
-
-			/*
-			 * Make sure there are at least 4 free bits in 'chunk'.
-			 * If not, this hexdigit will overflow 'chunk', so
-			 * throw an error.
-			 */
-			if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
-				return -EOVERFLOW;
-
-			chunk = (chunk << 4) | hex_to_bin(c);
-			totaldigits++;
-		}
-		if (ndigits == totaldigits)
-			return -EINVAL;
-		if (nchunks == 0 && chunk == 0)
-			continue;
-
-		__bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
-		*maskp |= chunk;
-		nchunks++;
-		nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
-		if (nbits > nmaskbits)
-			return -EOVERFLOW;
-	} while (buflen && c == ',');
-
-	return 0;
-}
-EXPORT_SYMBOL(__bitmap_parse);
-
 /**
  * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
  *
@@ -464,7 +373,7 @@ int bitmap_parse_user(const char __user *ubuf,
 	if (IS_ERR(buf))
 		return PTR_ERR(buf);
 
-	ret = bitmap_parse(buf, ulen, maskp, nmaskbits);
+	ret = bitmap_parse(buf, UINT_MAX, maskp, nmaskbits);
 
 	kfree(buf);
 	return ret;
@@ -575,6 +484,14 @@ static const char *bitmap_find_region(const char *str)
 	return end_of_str(*str) ? NULL : str;
 }
 
+static const char *bitmap_find_region_reverse(const char *start, const char *end)
+{
+	while (start <= end && __end_of_region(*end))
+		end--;
+
+	return end;
+}
+
 static const char *bitmap_parse_region(const char *str, struct region *r)
 {
 	str = bitmap_getnum(str, &r->start);
@@ -698,6 +615,83 @@ int bitmap_parselist_user(const char __user *ubuf,
 }
 EXPORT_SYMBOL(bitmap_parselist_user);
 
+static const char *bitmap_get_x32_reverse(const char *start,
+					const char *end, u32 *num)
+{
+	u32 ret = 0;
+	int c, i;
+
+	if (!isxdigit(*end))
+		return ERR_PTR(-EINVAL);
+
+	for (i = 0; i < 32; i += 4) {
+		c = hex_to_bin(*end--);
+		if (c < 0)
+			return ERR_PTR(-EINVAL);
+
+		ret |= c << i;
+
+		if (start > end || __end_of_region(*end))
+			goto out;
+	}
+
+	if (isxdigit(*end))
+		return ERR_PTR(-EOVERFLOW);
+out:
+	*num = ret;
+	return end;
+}
+
+/**
+ * bitmap_parse - convert an ASCII hex string into a bitmap.
+ * @start: pointer to buffer containing string.
+ * @buflen: buffer size in bytes.  If string is smaller than this
+ *    then it must be terminated with a \0 or \n. In that case,
+ *    UINT_MAX may be provided instead of string length.
+ * @maskp: pointer to bitmap array that will contain result.
+ * @nmaskbits: size of bitmap, in bits.
+ *
+ * Commas group hex digits into chunks.  Each chunk defines exactly 32
+ * bits of the resultant bitmask.  No chunk may specify a value larger
+ * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
+ * then leading 0-bits are prepended.  %-EINVAL is returned for illegal
+ * characters. Grouping such as "1,,5", ",44", "," or "" is allowed.
+ * Leading, embedded and trailing whitespace accepted.
+ */
+int bitmap_parse(const char *start, unsigned int buflen,
+		unsigned long *maskp, int nmaskbits)
+{
+	const char *end = strnchrnul(start, buflen, '\n') - 1;
+	int chunks = BITS_TO_U32(nmaskbits);
+	u32 *bitmap = (u32 *)maskp;
+	int unset_bit;
+
+	while (1) {
+		end = bitmap_find_region_reverse(start, end);
+		if (start > end)
+			break;
+
+		if (!chunks--)
+			return -EOVERFLOW;
+
+		end = bitmap_get_x32_reverse(start, end, bitmap++);
+		if (IS_ERR(end))
+			return PTR_ERR(end);
+	}
+
+	unset_bit = (BITS_TO_U32(nmaskbits) - chunks) * 32;
+	if (unset_bit < nmaskbits) {
+		bitmap_clear(maskp, unset_bit, nmaskbits - unset_bit);
+		return 0;
+	}
+
+	if (find_next_bit(maskp, unset_bit, nmaskbits) != unset_bit)
+		return -EOVERFLOW;
+
+	return 0;
+}
+EXPORT_SYMBOL(bitmap_parse);
+
 
 #ifdef CONFIG_NUMA
 /**
-- 
2.20.1

Re: [PATCH 5/7] lib: rework bitmap_parse()

[Andy Shevchenko]

On Sun, Sep 08, 2019 at 08:30:19PM -0700, Yury Norov wrote:
> bitmap_parse() is ineffective and full of opaque variables and opencoded
> parts. It leads to hard understanding and usage of it. This rework
> includes:
>  - remove bitmap_shift_left() call from the cycle. Now it makes the
>    complexity of the algorithm as O(nbits^2). In the suggested approach
>    the input string is parsed in reverse direction, so no shifts needed;
>  - relax requirement on a single comma and no white spaces between chunks.
>    It is considered useful in scripting, and it aligns with
>    bitmap_parselist();
>  - split bitmap_parse() to small readable helpers;
>  - make an explicit calculation of the end of input line at the
>    beginning, so users of the bitmap_parse() won't bother doing this.

> +static const char *bitmap_get_x32_reverse(const char *start,
> +					const char *end, u32 *num)
> +{
> +	u32 ret = 0;
> +	int c, i;
> +

> +	if (!isxdigit(*end))
> +		return ERR_PTR(-EINVAL);

This seems redundant...

> +
> +	for (i = 0; i < 32; i += 4) {

> +		c = hex_to_bin(*end--);
> +		if (c < 0)
> +			return ERR_PTR(-EINVAL);

...because this will do the same check.

Am I right?

> +
> +		ret |= c << i;
> +
> +		if (start > end || __end_of_region(*end))
> +			goto out;
> +	}
> +

> +	if (isxdigit(*end))
> +		return ERR_PTR(-EOVERFLOW);

hex_to_bin() doesn't rely on ctype array, won't drain caches.
I guess it's not a fast path, so, either will work.

> +out:
> +	*num = ret;
> +	return end;
> +}

-- 
With Best Regards,
Andy Shevchenko

[PATCH 6/7] lib: new testcases for bitmap_parse{_user}

[Yury Norov]

New version of bitmap_parse() is unified with bitmap_parse_list(),
and therefore:
 - weakens rules on whitespaces and commas between hex chunks;
 - in addition to \0 allows using \n as the line ending symbol;
 - allows passing UINT_MAX or any other big number as the length
   of input string instead of actual string length.

The patch covers the cases.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 lib/test_bitmap.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index e306d3da12019..d9fe7c89e6a94 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -344,14 +344,22 @@ static const unsigned long parse_test2[] __initconst = {
 };
 
 static const struct test_bitmap_parselist parse_tests[] __initconst = {
+	{0, "",				&parse_test[0 * step], 32, 0},
+	{0, " ",			&parse_test[0 * step], 32, 0},
 	{0, "0",			&parse_test[0 * step], 32, 0},
+	{0, "0\n",			&parse_test[0 * step], 32, 0},
 	{0, "1",			&parse_test[1 * step], 32, 0},
 	{0, "deadbeef",			&parse_test[2 * step], 32, 0},
 	{0, "1,0",			&parse_test[3 * step], 33, 0},
+	{0, "deadbeef,\n,0,1",		&parse_test[2 * step], 96, 0},
 
 	{0, "deadbeef,1,0",		&parse_test2[0 * 2 * step], 96, 0},
 	{0, "baadf00d,deadbeef,1,0",	&parse_test2[1 * 2 * step], 128, 0},
 	{0, "badf00d,deadbeef,1,0",	&parse_test2[2 * 2 * step], 124, 0},
+	{0, "badf00d,deadbeef,1,0",	&parse_test2[2 * 2 * step], 124, NO_LEN},
+	{0, "  badf00d,deadbeef,1,0  ",	&parse_test2[2 * 2 * step], 124, 0},
+	{0, " , badf00d,deadbeef,1,0 , ",	&parse_test2[2 * 2 * step], 124, 0},
+	{0, " , badf00d, ,, ,,deadbeef,1,0 , ",	&parse_test2[2 * 2 * step], 124, 0},
 
 	{-EINVAL,    "goodfood,deadbeef,1,0",	NULL, 128, 0},
 	{-EOVERFLOW, "3,0",			NULL, 33, 0},
-- 
2.20.1

[PATCH 7/7] cpumask: don't calculate length of the input string

[Yury Norov]

New design of inner bitmap_parse() allows to avoid
calculating the size of a null-terminated string.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 include/linux/cpumask.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 78a73eba64dd6..d5cc88514aee6 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -663,9 +663,7 @@ static inline int cpumask_parselist_user(const char __user *buf, int len,
  */
 static inline int cpumask_parse(const char *buf, struct cpumask *dstp)
 {
-	unsigned int len = strchrnul(buf, '\n') - buf;
-
-	return bitmap_parse(buf, len, cpumask_bits(dstp), nr_cpumask_bits);
+	return bitmap_parse(buf, UINT_MAX, cpumask_bits(dstp), nr_cpumask_bits);
 }
 
 /**
-- 
2.20.1