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Message-ID: <20221209063434.1566682-1-lilingfeng3@huawei.com>
Date: Fri, 9 Dec 2022 14:34:34 +0800
From: Li Lingfeng <lilingfeng3@...wei.com>
To: <linux-kernel@...r.kernel.org>
CC: <tj@...nel.org>, <jack@...e.cz>, <bingjingc@...ology.com>,
<ebiggers@...gle.com>, <james.smart@...adcom.com>,
<houtao1@...wei.com>, <yi.zhang@...wei.com>,
<yangerkun@...wei.com>, <yukuai3@...wei.com>,
<lilingfeng3@...wei.com>
Subject: [PATCH-next] lib: parser: optimize match_NUMER apis to use local array
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.
Introducing a helper which use 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@...wei.com>
---
lib/parser.c | 56 +++++++++++++++++++++++++++++++++++-----------------
1 file changed, 38 insertions(+), 18 deletions(-)
diff --git a/lib/parser.c b/lib/parser.c
index bcb23484100e..d4f4c81ff653 100644
--- a/lib/parser.c
+++ b/lib/parser.c
@@ -11,6 +11,30 @@
#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 U64_MAX_SIZE
+ */
+#define U64_MAX_SIZE 23
+
+static int match_strdup_local(const substring_t *s, char *buf)
+{
+ size_t len = s->to - s->from;
+
+ if (!s->from)
+ return -EINVAL;
+
+ if (len > U64_MAX_SIZE)
+ return -ERANGE;
+
+ memcpy(buf, s->from, len);
+ buf[len] = '\0';
+ return 0;
+}
+
/**
* match_one - Determines if a string matches a simple pattern
* @s: the string to examine for presence of the pattern
@@ -129,15 +153,13 @@ EXPORT_SYMBOL(match_token);
static int match_number(substring_t *s, int *result, int base)
{
char *endp;
- char *buf;
+ char buf[U64_MAX_SIZE + 1];
int ret;
long val;
- buf = match_strdup(s);
- if (!buf)
- return -ENOMEM;
-
- ret = 0;
+ ret = match_strdup_local(s, buf);
+ if (ret)
+ return ret;
val = simple_strtol(buf, &endp, base);
if (endp == buf)
ret = -EINVAL;
@@ -145,7 +167,6 @@ static int match_number(substring_t *s, int *result, int base)
ret = -ERANGE;
else
*result = (int) val;
- kfree(buf);
return ret;
}
@@ -163,18 +184,16 @@ 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[U64_MAX_SIZE + 1];
int ret;
u64 val;
- buf = match_strdup(s);
- if (!buf)
- return -ENOMEM;
-
+ ret = match_strdup_local(s, buf);
+ if (ret)
+ return ret;
ret = kstrtoull(buf, base, &val);
if (!ret)
*result = val;
- kfree(buf);
return ret;
}
@@ -207,12 +226,13 @@ EXPORT_SYMBOL(match_int);
int match_uint(substring_t *s, unsigned int *result)
{
int err = -ENOMEM;
- char *buf = match_strdup(s);
+ char buf[U64_MAX_SIZE + 1];
- if (buf) {
- err = kstrtouint(buf, 10, result);
- kfree(buf);
- }
+ err = match_strdup_local(s, buf);
+ if (err)
+ return err;
+
+ err = kstrtouint(buf, 10, result);
return err;
}
EXPORT_SYMBOL(match_uint);
--
2.31.1
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