Re: [PATCH] Reduce stack used by lib/hexdump.c

Randy Dunlap
2007-11-29T21:04:20Z

Joe Perches wrote:
> 200 bytes on stack might be a bit much.
>
> Size goes up to
> text data bss dec hex filename
> 1142 0 0 1142 476 lib/hexdump.o
> Without the WARN_ON
> 1053 0 0 1053 41d lib/hexdump.o
> Before this patch
> 1004 0 0 1004 3ec lib/hexdump.o
>
> Win some/lose some...
>
> Signed-off-by: Joe Perches <joe@perches.com>

Acked-by: Randy Dunlap <randy.dunlap@oracle.com>

> diff --git a/lib/hexdump.c b/lib/hexdump.c
> index 70e23fb..be94934 100644
> --- a/lib/hexdump.c
> +++ b/lib/hexdump.c
> @@ -140,13 +140,20 @@ EXPORT_SYMBOL(hex_dump_to_buffer);
> * Example output using %DUMP_PREFIX_ADDRESS and 4-byte mode:
> * ffffffff88089af0: 73727170 77767574 7b7a7978 7f7e7d7c pqrstuvwxyz{|}~.
> */
> +
> +#define HEX_LINE_SIZE 200
> +
> void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
> int rowsize, int groupsize,
> const void *buf, size_t len, bool ascii)
> {
> const u8 *ptr = buf;
> int i, linelen, remaining = len;
> - unsigned char linebuf[200];
> + unsigned char *linebuf;
> +
> + linebuf = kmalloc(HEX_LINE_SIZE, GFP_KERNEL);
> + if (!linebuf) {
> + WARN_ON(1);
> + return;
> + }
>
> if (rowsize != 16 && rowsize != 32)
> rowsize = 16;
> @@ -155,7 +162,7 @@ void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
> linelen = min(remaining, rowsize);
> remaining -= rowsize;
> hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
> - linebuf, sizeof(linebuf), ascii);
> + linebuf, HEX_LINE_SIZE, ascii);
>
> switch (prefix_type) {
> case DUMP_PREFIX_ADDRESS:
> @@ -170,6 +177,7 @@ void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
> break;
> }
> }
> + kfree(linebuf);
> }
> EXPORT_SYMBOL(print_hex_dump);

--
~Randy