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Date: Wed, 01 Jul 2015 12:16:46 +0300
From: Yury <yury.norov@...il.com>
To: Pan Xinhui <xinhuix.pan@...el.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: Andrew Morton <akpm@...ux-foundation.org>,
Rasmus Villemoes <linux@...musvillemoes.dk>, tj@...nel.org,
peterz@...radead.org, sudeep.holla@....com, mina86@...a86.com,
"mnipxh@....com" <mnipxh@....com>,
Alexey Klimov <klimov.linux@...il.com>
Subject: Re: [PATCH V3] lib/bitmap.c: rewrite __bitmap_parse && __bitmap_parselist
> Subject: lib/bitmap.c: rewrite __bitmap_parse && __bitmap_parselist
scripts/checkpatch.pl
lib_bitmap.c:-rewrite-__bitmap_parse-__bitmap_parselist.patch
total: 134 errors, 1 warnings, 284 lines checked
NOTE: whitespace errors detected, you may wish to use
scripts/cleanpatch or
scripts/cleanfile
Most of them are about DOS line endings, but it prevents me to apply
your patch:
patch -p1 <
lib_bitmap.c:-rewrite-__bitmap_parse-__bitmap_parselist.patch
(Stripping trailing CRs from patch; use --binary to disable.)
patching file lib/bitmap.c
Hunk #1 FAILED at 16.
Hunk #2 FAILED at 331.
Hunk #3 FAILED at 359.
Hunk #4 FAILED at 417.
Hunk #5 FAILED at 503.
5 out of 5 hunks FAILED -- saving rejects to file lib/bitmap.c.rej
>
> add __bitmap_parse_common to match any contents and return expected
reslut.
>
> as __bitmap_parse_common need NULL-terminated string, we alloc a new buf.
>
> this patch also fix an unexpected parse result issue in
__bitmap_parselist.
>
> Signed-off-by: Pan Xinhui <xinhuix.pan@...el.com>
> ---
> lib/bitmap.c | 238
+++++++++++++++++++++++++++++++++--------------------------
> 1 file changed, 134 insertions(+), 104 deletions(-)
> ---
> change log
> v3:
> __bitmap_parselist now allow some extra input, like ",2, 3,,,, 5-8",
at least one digit inside.
> input like " " ", " is still not allowed.
>
> V2:
> __bitmap_parse_common need *base* to parse correct result
>
> V1:
> add __bitmap_parse_common and rewrite __bitmap_parse &&
__bitmap_parselist
> ---
>
> diff --git a/lib/bitmap.c b/lib/bitmap.c
> index 64c0926..f2095e1d 100644
> --- a/lib/bitmap.c
> +++ b/lib/bitmap.c
> @@ -16,6 +16,8 @@
> #include <asm/page.h>
> #include <asm/uaccess.h>
>
> +#include <linux/parser.h>
> +#include <linux/slab.h>
> /*
> * bitmaps provide an array of bits, implemented using an an
> * array of unsigned longs. The number of valid bits in a
> @@ -331,6 +333,58 @@ again:
> EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
>
> /*
> + * __bitmap_parse_common - parse expected number from buf
> + * Return 0 on success.
> + * there two patterns.
> + * if buf's contents did not match any of them, reutrn equivalent error.
> + * Notice buf's contents may be changed.
> + */
> +static int __bitmap_parse_common(char *buf, unsigned int buflen,
> + unsigned long *a, unsigned long *b, int base)
It looks weird, and I don't like in your version too much:
Name is bad.
There's nothing about bitmap. You just parsing a string for two
patterns: %d, and %d-%d.
You do your work twice (at least): first you detect digits in
match_token, then - in kstrtoul.
You allocate kbuf unconditionally, no matter you need it or not.
You do more than one thing in __bitmap_parse_common (you search number
and region).
You modify initial string.
Let's consider a more straight interface:
/*
* I don't know why this function is not written yet.
* Maybe it's something ideological...
*/
void set_bits(unsigned long *bitmap, unsigned long start, unsigned
long len);
/*
* Takes care of all user whitespaces and commas,
* Return endp, or error if parse fails, or null if string reached
the end.
*/
char *parse_range(const char *buf, unsigned long *start, unsigned
long *len);
than pattern usage would be:
while (str = parse_range(str, &start, &len)) {
if (IS_ERROR(str))
return ...;
if (start + len >= nbits)
return ...;
set_bits(bitmap, start, len);
}
> +{
> + int ret;
> + int token;
> + const match_table_t table = {
> + {
> + .token = 1,
> + .pattern = "%x",
> + },
> + {
> + .token = 2,
> + .pattern = "%x-%x",
> + },
> + {
> + .token = 0,
> + .pattern = NULL,
> + }
> + };
> + substring_t substr[MAX_OPT_ARGS];
> +
> + if (!buflen || !a)
> + return -EINVAL;
> + token = match_token((char *)buf, table, substr);
> + switch (token) {
> + case 1:
> + *substr[0].to = '\0';
> + ret = kstrtoul(substr[0].from, base, a);
> + if (b)
> + *b = *a;
> + break;
> + case 2:
> + *substr[0].to = '\0';
> + *substr[1].to = '\0';
> + ret = kstrtoul(substr[0].from, base, a);
> + ret |= b ? kstrtoul(substr[1].from, base, b) : -EINVAL;
> + break;
> + default:
> + ret = -EINVAL;
> + break;
> + }
> + return ret;
> +}
> +
> +/*
> * Bitmap printing & parsing functions: first version by Nadia
Yvette Chambers,
> * second version by Paul Jackson, third by Joe Korty.
> */
> @@ -359,57 +413,45 @@ 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;
> + int nchunks, nbits, ret;
> + unsigned long a;
> u32 chunk;
> const char __user __force *ubuf = (const char __user __force *)buf;
> + char *kbuf, *endp;
> +
> + if (!buflen)
> + return -EINVAL;
> + kbuf = kmalloc(buflen + 1, GFP_KERNEL);
> + if (!kbuf)
> + return -ENOMEM;
> + if (is_user) {
> + if (copy_from_user(kbuf, ubuf, buflen) != 0) {
> + kfree(kbuf);
> + return -EFAULT;
> + }
> + } else
> + memcpy(kbuf, buf, buflen);
> + kbuf[buflen] = '\0';
> + buf = strim(kbuf);
>
> bitmap_zero(maskp, nmaskbits);
>
> - nchunks = nbits = totaldigits = c = 0;
> + nchunks = nbits = 0;
> do {
> - chunk = ndigits = 0;
> -
> - /* 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);
> - ndigits++; totaldigits++;
> + endp = strchr(buf, ',');
> + if (endp)
> + *endp = '\0';
> + ret = __bitmap_parse_common((char *)buf, strlen(buf),
> + &a, NULL, 16);
> + if (ret)
> + break;
> + buf = endp + 1;
> +
> + if (unlikely(a > U32_MAX)) {
> + ret = -ERANGE;
> + break;
> }
> - if (ndigits == 0)
> - return -EINVAL;
> + chunk = (u32)a;
> if (nchunks == 0 && chunk == 0)
> continue;
>
> @@ -417,11 +459,13 @@ int __bitmap_parse(const char *buf, unsigned
int buflen,
> *maskp |= chunk;
> nchunks++;
> nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
> - if (nbits > nmaskbits)
> - return -EOVERFLOW;
> - } while (buflen && c == ',');
> -
> - return 0;
> + if (nbits > nmaskbits) {
> + ret = -EOVERFLOW;
> + break;
> + }
> + } while (endp);
> + kfree(kbuf);
> + return ret;
> }
> EXPORT_SYMBOL(__bitmap_parse);
>
> @@ -503,70 +547,56 @@ static int __bitmap_parselist(const char *buf,
unsigned int buflen,
> int is_user, unsigned long *maskp,
> int nmaskbits)
> {
> - unsigned a, b;
> - int c, old_c, totaldigits;
> + unsigned long a, b;
> + int ret = -EINVAL;
> const char __user __force *ubuf = (const char __user __force *)buf;
> - int exp_digit, in_range;
> + char *kbuf, *endp, *ibuf;
> +
> + if (!buflen)
> + return -EINVAL;
> + ibuf = kbuf = kmalloc(buflen + 1, GFP_KERNEL);
> + if (!kbuf)
> + return -ENOMEM;
> + if (is_user) {
> + if (copy_from_user(kbuf, ubuf, buflen) != 0) {
> + kfree(kbuf);
> + return -EFAULT;
> + }
> + } else
> + memcpy(kbuf, buf, buflen);
> + kbuf[buflen] = '\0';
>
> - totaldigits = c = 0;
> bitmap_zero(maskp, nmaskbits);
> do {
> - exp_digit = 1;
> - in_range = 0;
> - a = b = 0;
> -
> - /* Get the next cpu# or a range of cpu#'s */
> - 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 a cpu# or range */
> - if (c == '\0' || c == ',')
> - break;
> -
> - if (c == '-') {
> - if (exp_digit || in_range)
> - return -EINVAL;
> - b = 0;
> - in_range = 1;
> - exp_digit = 1;
> - continue;
> - }
> -
> - if (!isdigit(c))
> - return -EINVAL;
> -
> - b = b * 10 + (c - '0');
> - if (!in_range)
> - a = b;
> - exp_digit = 0;
> - totaldigits++;
> + endp = strchr(ibuf, ',');
> + if (endp)
> + *endp = '\0';
> + ibuf = strim(ibuf);
> + if (*ibuf == 0) {
> + ibuf = endp + 1;
> + continue;
> + }
> + ret = __bitmap_parse_common(ibuf, strlen(ibuf),
> + &a, &b, 0);
> + if (ret)
> + break;
> + ibuf = endp + 1;
> +
> + if (!(a <= b)) {
> + ret = -EINVAL;
> + break;
> + }
> + if (b >= nmaskbits) {
> + ret = -ERANGE;
> + break;
> }
> - if (!(a <= b))
> - return -EINVAL;
> - if (b >= nmaskbits)
> - return -ERANGE;
> while (a <= b) {
> set_bit(a, maskp);
> a++;
> }
> - } while (buflen && c == ',');
> - return 0;
> + } while (endp);
> + kfree(kbuf);
> + return ret;
> }
>
> int bitmap_parselist(const char *bp, unsigned long *maskp, int
nmaskbits)
> --
> 1.9.1
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