Memory will be allocated to store substring_t in match_strdup(), which means
the caller of match_strdup() may need to be scheduled out to wait for reclaiming
memory.

Using local array to store substring_t to remove the restriction.

Link: https://lore.kernel.org/all/20221104023938.2346986-5-yukuai1@huaweicloud.com/
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
---
 v1->v2:
   change the name of buffer's length
   use match_strlcpy() to copy string and keep string length check
 lib/parser.c | 42 +++++++++++++++++++++++-------------------
 1 file changed, 23 insertions(+), 19 deletions(-)

diff --git a/lib/parser.c b/lib/parser.c
index bcb23484100e..0d00f0adb063 100644
--- a/lib/parser.c
+++ b/lib/parser.c
@@ -11,6 +11,15 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 
+/*
+ * max size needed by diffrent bases to express U64
+ * HEX: "0xFFFFFFFFFFFFFFFF" --> 18
+ * DEC: "18446744073709551615" --> 20
+ * OCT: "01777777777777777777777" --> 23
+ * pick the max one to define NUMBER_BUF_LEN
+ */
+#define NUMBER_BUF_LEN 24
+
 /**
  * match_one - Determines if a string matches a simple pattern
  * @s: the string to examine for presence of the pattern
@@ -129,14 +138,13 @@ EXPORT_SYMBOL(match_token);
 static int match_number(substring_t *s, int *result, int base)
 {
 	char *endp;
-	char *buf;
+	char buf[NUMBER_BUF_LEN];
 	int ret;
 	long val;
 
-	buf = match_strdup(s);
-	if (!buf)
-		return -ENOMEM;
-
+	if ((s->to - s->from) >= NUMBER_BUF_LEN)
+		return -ERANGE;
+	match_strlcpy(buf, s, NUMBER_BUF_LEN);
 	ret = 0;
 	val = simple_strtol(buf, &endp, base);
 	if (endp == buf)
@@ -145,7 +153,6 @@ static int match_number(substring_t *s, int *result, int base)
 		ret = -ERANGE;
 	else
 		*result = (int) val;
-	kfree(buf);
 	return ret;
 }
 
@@ -163,18 +170,16 @@ static int match_number(substring_t *s, int *result, int base)
  */
 static int match_u64int(substring_t *s, u64 *result, int base)
 {
-	char *buf;
+	char buf[NUMBER_BUF_LEN];
 	int ret;
 	u64 val;
 
-	buf = match_strdup(s);
-	if (!buf)
-		return -ENOMEM;
-
+	if ((s->to - s->from) >= NUMBER_BUF_LEN)
+		return -ERANGE;
+	match_strlcpy(buf, s, NUMBER_BUF_LEN);
 	ret = kstrtoull(buf, base, &val);
 	if (!ret)
 		*result = val;
-	kfree(buf);
 	return ret;
 }
 
@@ -206,14 +211,13 @@ EXPORT_SYMBOL(match_int);
  */
 int match_uint(substring_t *s, unsigned int *result)
 {
-	int err = -ENOMEM;
-	char *buf = match_strdup(s);
+	char buf[NUMBER_BUF_LEN];
 
-	if (buf) {
-		err = kstrtouint(buf, 10, result);
-		kfree(buf);
-	}
-	return err;
+	if ((s->to - s->from) >= NUMBER_BUF_LEN)
+		return -ERANGE;
+	match_strlcpy(buf, s, NUMBER_BUF_LEN);
+
+	return kstrtouint(buf, 10, result);
 }
 EXPORT_SYMBOL(match_uint);
 
-- 
2.31.1

在 2022/12/13 22:17, Li Lingfeng 写道:
> Memory will be allocated to store substring_t in match_strdup(), which means
> the caller of match_strdup() may need to be scheduled out to wait for reclaiming
> memory.
>
> Using local array to store substring_t to remove the restriction.
>
> Link: https://lore.kernel.org/all/20221104023938.2346986-5-yukuai1@huaweicloud.com/
> Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
> ---
>   v1->v2:
>     change the name of buffer's length
>     use match_strlcpy() to copy string and keep string length check
>   lib/parser.c | 42 +++++++++++++++++++++++-------------------
>   1 file changed, 23 insertions(+), 19 deletions(-)
>
> diff --git a/lib/parser.c b/lib/parser.c

I can't find the maintainer of this module through the script, does 
anyone know?

[lilingfeng@ceph-admin linux-next]$ ./scripts/get_maintainer.pl 
0001-lib-parser-optimize-match_NUMER-apis-to-use-local-ar.patch

Bad divisor in main::vcs_assign: 0
"GitAuthor: Li Lingfeng" <lilingfeng3@huawei.com> 
(authored:1/1=100%,added_lines:23/23=100%,removed_lines:19/19=100%)
linux-kernel@vger.kernel.org (open list)

Thanks.

> index bcb23484100e..0d00f0adb063 100644
> --- a/lib/parser.c
> +++ b/lib/parser.c
> @@ -11,6 +11,15 @@
>   #include <linux/slab.h>
>   #include <linux/string.h>
>   
> +/*
> + * max size needed by diffrent bases to express U64
> + * HEX: "0xFFFFFFFFFFFFFFFF" --> 18
> + * DEC: "18446744073709551615" --> 20
> + * OCT: "01777777777777777777777" --> 23
> + * pick the max one to define NUMBER_BUF_LEN
> + */
> +#define NUMBER_BUF_LEN 24
> +
>   /**
>    * match_one - Determines if a string matches a simple pattern
>    * @s: the string to examine for presence of the pattern
> @@ -129,14 +138,13 @@ EXPORT_SYMBOL(match_token);
>   static int match_number(substring_t *s, int *result, int base)
>   {
>   	char *endp;
> -	char *buf;
> +	char buf[NUMBER_BUF_LEN];
>   	int ret;
>   	long val;
>   
> -	buf = match_strdup(s);
> -	if (!buf)
> -		return -ENOMEM;
> -
> +	if ((s->to - s->from) >= NUMBER_BUF_LEN)
> +		return -ERANGE;
> +	match_strlcpy(buf, s, NUMBER_BUF_LEN);
>   	ret = 0;
>   	val = simple_strtol(buf, &endp, base);
>   	if (endp == buf)
> @@ -145,7 +153,6 @@ static int match_number(substring_t *s, int *result, int base)
>   		ret = -ERANGE;
>   	else
>   		*result = (int) val;
> -	kfree(buf);
>   	return ret;
>   }
>   
> @@ -163,18 +170,16 @@ static int match_number(substring_t *s, int *result, int base)
>    */
>   static int match_u64int(substring_t *s, u64 *result, int base)
>   {
> -	char *buf;
> +	char buf[NUMBER_BUF_LEN];
>   	int ret;
>   	u64 val;
>   
> -	buf = match_strdup(s);
> -	if (!buf)
> -		return -ENOMEM;
> -
> +	if ((s->to - s->from) >= NUMBER_BUF_LEN)
> +		return -ERANGE;
> +	match_strlcpy(buf, s, NUMBER_BUF_LEN);
>   	ret = kstrtoull(buf, base, &val);
>   	if (!ret)
>   		*result = val;
> -	kfree(buf);
>   	return ret;
>   }
>   
> @@ -206,14 +211,13 @@ EXPORT_SYMBOL(match_int);
>    */
>   int match_uint(substring_t *s, unsigned int *result)
>   {
> -	int err = -ENOMEM;
> -	char *buf = match_strdup(s);
> +	char buf[NUMBER_BUF_LEN];
>   
> -	if (buf) {
> -		err = kstrtouint(buf, 10, result);
> -		kfree(buf);
> -	}
> -	return err;
> +	if ((s->to - s->from) >= NUMBER_BUF_LEN)
> +		return -ERANGE;
> +	match_strlcpy(buf, s, NUMBER_BUF_LEN);
> +
> +	return kstrtouint(buf, 10, result);
>   }
>   EXPORT_SYMBOL(match_uint);
>   

On Tue, Jan 10, 2023 at 09:49:21PM +0800, lilingfeng (A) wrote:
> 
> 在 2022/12/13 22:17, Li Lingfeng 写道:
> > Memory will be allocated to store substring_t in match_strdup(), which means
> > the caller of match_strdup() may need to be scheduled out to wait for reclaiming
> > memory.
> > 
> > Using local array to store substring_t to remove the restriction.
> > 
> > Link: https://lore.kernel.org/all/20221104023938.2346986-5-yukuai1@huaweicloud.com/
> > Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
> > ---
> >   v1->v2:
> >     change the name of buffer's length
> >     use match_strlcpy() to copy string and keep string length check
> >   lib/parser.c | 42 +++++++++++++++++++++++-------------------
> >   1 file changed, 23 insertions(+), 19 deletions(-)
> > 
> > diff --git a/lib/parser.c b/lib/parser.c
> 
> I can't find the maintainer of this module through the script, does anyone
> know?

Oh, send it to Andrew Morton <akpm@linux-foundation.org>.

Thanks.

-- 
tejun

On Tue, Dec 13, 2022 at 10:17:55PM +0800, Li Lingfeng wrote:
> Memory will be allocated to store substring_t in match_strdup(), which means
> the caller of match_strdup() may need to be scheduled out to wait for reclaiming
> memory.
> 
> Using local array to store substring_t to remove the restriction.
> 
> Link: https://lore.kernel.org/all/20221104023938.2346986-5-yukuai1@huaweicloud.com/
> Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun