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Date: Tue, 16 Apr 2019 16:18:08 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Yury Norov <yury.norov@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Arnd Bergmann <arnd@...db.de>,
Kees Cook <keescook@...omium.org>,
Matthew Wilcox <willy@...radead.org>,
Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
Mike Travis <travis@....com>,
Guenter Roeck <linux@...ck-us.net>,
Yury Norov <ynorov@...vell.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] lib: rework bitmap_parselist
On Mon, Apr 15, 2019 at 11:37:58PM -0700, Yury Norov wrote:
> From: Yury Norov <ynorov@...vell.com>
>
> Remove __bitmap_parselist helper and split the function to logical
> parts.
>
One comment below.
Overall looks good to me, thanks!
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Signed-off-by: Yury Norov <ynorov@...vell.com>
> ---
> lib/bitmap.c | 255 ++++++++++++++++++++++++++++-----------------------
> 1 file changed, 142 insertions(+), 113 deletions(-)
>
> diff --git a/lib/bitmap.c b/lib/bitmap.c
> index c63ddd06a5da..f235434df87b 100644
> --- a/lib/bitmap.c
> +++ b/lib/bitmap.c
> @@ -20,6 +20,8 @@
>
> #include <asm/page.h>
>
> +#include "kstrtox.h"
> +
> /**
> * DOC: bitmap introduction
> *
> @@ -477,12 +479,128 @@ int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
> }
> EXPORT_SYMBOL(bitmap_print_to_pagebuf);
>
> +/*
> + * Region 9-38:4/10 describes the following bitmap structure:
> + * 0 9 12 18 38
> + * .........****......****......****......
> + * ^ ^ ^ ^
> + * start off group_len end
> + */
> +struct region {
> + unsigned int start;
> + unsigned int off;
> + unsigned int group_len;
> + unsigned int end;
> +};
> +
> +static int bitmap_set_region(const struct region *r,
> + unsigned long *bitmap, int nbits)
> +{
> + unsigned int start;
> +
> + if (r->end >= nbits)
> + return -ERANGE;
> +
> + for (start = r->start; start <= r->end; start += r->group_len)
> + bitmap_set(bitmap, start, min(r->end - start + 1, r->off));
> +
> + return 0;
> +}
> +
> +static int bitmap_check_region(const struct region *r)
> +{
> + if (r->start > r->end || r->group_len == 0 || r->off > r->group_len)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static const char *bitmap_getnum(const char *str, unsigned int *num)
> +{
> + unsigned long long n;
> + unsigned int len;
> +
> + len = _parse_integer(str, 10, &n);
I think we are good here, since it's only for use inside lib itself.
> + if (!len)
> + return ERR_PTR(-EINVAL);
> + if (len & KSTRTOX_OVERFLOW || n != (unsigned int)n)
Second part is simple to compare to UINT_MAX: "n > UINT_MAX", or
"upper_32_bits(n)" would work as well.
Among all I would rather go to comparison with limits, i.e. UINT_MAX.
> + return ERR_PTR(-EOVERFLOW);
> +
> + *num = n;
> + return str + len;
> +}
> +
> +static inline bool end_of_str(char c)
> +{
> + return c == '\0' || c == '\n';
> +}
> +
> +static inline bool __end_of_region(char c)
> +{
> + return isspace(c) || c == ',';
> +}
> +
> +static inline bool end_of_region(char c)
> +{
> + return __end_of_region(c) || end_of_str(c);
> +}
> +
> +/*
> + * The format allows commas and whitespases at the beginning
> + * of the region.
> + */
> +static const char *bitmap_find_region(const char *str)
> +{
> + while (__end_of_region(*str))
> + str++;
> +
> + return end_of_str(*str) ? NULL : str;
> +}
> +
> +static const char *bitmap_parse_region(const char *str, struct region *r)
> +{
> + str = bitmap_getnum(str, &r->start);
> + if (IS_ERR(str))
> + return str;
> +
> + if (end_of_region(*str))
> + goto no_end;
> +
> + if (*str != '-')
> + return ERR_PTR(-EINVAL);
> +
> + str = bitmap_getnum(str + 1, &r->end);
> + if (IS_ERR(str))
> + return str;
> +
> + if (end_of_region(*str))
> + goto no_pattern;
> +
> + if (*str != ':')
> + return ERR_PTR(-EINVAL);
> +
> + str = bitmap_getnum(str + 1, &r->off);
> + if (IS_ERR(str))
> + return str;
> +
> + if (*str != '/')
> + return ERR_PTR(-EINVAL);
> +
> + return bitmap_getnum(str + 1, &r->group_len);
> +
> +no_end:
> + r->end = r->start;
> +no_pattern:
> + r->off = r->end + 1;
> + r->group_len = r->end + 1;
> +
> + return end_of_str(*str) ? NULL : str;
> +}
> +
> /**
> - * __bitmap_parselist - convert list format ASCII string to bitmap
> - * @buf: read nul-terminated user string from this buffer
> - * @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
> + * bitmap_parselist - convert list format ASCII string to bitmap
> + * @buf: read user string from this buffer; must be terminated
> + * with a \0 or \n.
> * @maskp: write resulting mask here
> * @nmaskbits: number of bits in mask to be written
> *
> @@ -498,127 +616,38 @@ EXPORT_SYMBOL(bitmap_print_to_pagebuf);
> *
> * Returns: 0 on success, -errno on invalid input strings. Error values:
> *
> - * - ``-EINVAL``: second number in range smaller than first
> + * - ``-EINVAL``: wrong region format
> * - ``-EINVAL``: invalid character in string
> * - ``-ERANGE``: bit number specified too large for mask
> + * - ``-EOVERFLOW``: integer overflow in the input parameters
> */
> -static int __bitmap_parselist(const char *buf, unsigned int buflen,
> - int is_user, unsigned long *maskp,
> - int nmaskbits)
> +int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
> {
> - unsigned int a, b, old_a, old_b;
> - unsigned int group_size, used_size, off;
> - int c, old_c, totaldigits, ndigits;
> - const char __user __force *ubuf = (const char __user __force *)buf;
> - int at_start, in_range, in_partial_range;
> + struct region r;
> + long ret;
>
> - totaldigits = c = 0;
> - old_a = old_b = 0;
> - group_size = used_size = 0;
> bitmap_zero(maskp, nmaskbits);
> - do {
> - at_start = 1;
> - in_range = 0;
> - in_partial_range = 0;
> - a = b = 0;
> - ndigits = totaldigits;
> -
> - /* 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;
>
> - /* A '\0' or a ',' signal the end of a cpu# or range */
> - if (c == '\0' || c == ',')
> - break;
> - /*
> - * whitespaces between digits are not allowed,
> - * but it's ok if whitespaces are on head or tail.
> - * when old_c is whilespace,
> - * if totaldigits == ndigits, whitespace is on head.
> - * if whitespace is on tail, it should not run here.
> - * as c was ',' or '\0',
> - * the last code line has broken the current loop.
> - */
> - if ((totaldigits != ndigits) && isspace(old_c))
> - return -EINVAL;
> -
> - if (c == '/') {
> - used_size = a;
> - at_start = 1;
> - in_range = 0;
> - a = b = 0;
> - continue;
> - }
> + while (buf) {
> + buf = bitmap_find_region(buf);
> + if (buf == NULL)
> + return 0;
>
> - if (c == ':') {
> - old_a = a;
> - old_b = b;
> - at_start = 1;
> - in_range = 0;
> - in_partial_range = 1;
> - a = b = 0;
> - continue;
> - }
> + buf = bitmap_parse_region(buf, &r);
> + if (IS_ERR(buf))
> + return PTR_ERR(buf);
>
> - if (c == '-') {
> - if (at_start || in_range)
> - return -EINVAL;
> - b = 0;
> - in_range = 1;
> - at_start = 1;
> - continue;
> - }
> + ret = bitmap_check_region(&r);
> + if (ret)
> + return ret;
>
> - if (!isdigit(c))
> - return -EINVAL;
> + ret = bitmap_set_region(&r, maskp, nmaskbits);
> + if (ret)
> + return ret;
> + }
>
> - b = b * 10 + (c - '0');
> - if (!in_range)
> - a = b;
> - at_start = 0;
> - totaldigits++;
> - }
> - if (ndigits == totaldigits)
> - continue;
> - if (in_partial_range) {
> - group_size = a;
> - a = old_a;
> - b = old_b;
> - old_a = old_b = 0;
> - } else {
> - used_size = group_size = b - a + 1;
> - }
> - /* if no digit is after '-', it's wrong*/
> - if (at_start && in_range)
> - return -EINVAL;
> - if (!(a <= b) || group_size == 0 || !(used_size <= group_size))
> - return -EINVAL;
> - if (b >= nmaskbits)
> - return -ERANGE;
> - while (a <= b) {
> - off = min(b - a + 1, used_size);
> - bitmap_set(maskp, a, off);
> - a += group_size;
> - }
> - } while (buflen && c == ',');
> return 0;
> }
> -
> -int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
> -{
> - char *nl = strchrnul(bp, '\n');
> - int len = nl - bp;
> -
> - return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
> -}
> EXPORT_SYMBOL(bitmap_parselist);
>
>
> --
> 2.17.1
>
--
With Best Regards,
Andy Shevchenko
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