Re: [PATCH v3 1/5] seq_file: provide an analogue of print_hex_dump()

Andy Shevchenko
2014-09-01T08:37:11Z

On Sat, 2014-08-30 at 23:54 +0100, Al Viro wrote:
> On Mon, Aug 25, 2014 at 12:03:11PM +0300, Andy Shevchenko wrote:
> > The new seq_hex_dump() is a complete analogue of print_hex_dump().
> >
> > We have few users of this functionality already. It allows to reduce their
> > codebase.
>
> I really don't like the stack footprint.
>
> > + unsigned char linebuf[32 * 3 + 2 + 32 + 1];
>
> ... and extra copying for no good reason. Why not check that we have
> enough space in buffer and generate directly into it? See what e.g.
> seq_escape() is doing...

What about this variant?

@@ -794,6 +795,47 @@ void seq_pad(struct seq_file *m, char c)
}
EXPORT_SYMBOL(seq_pad);

+/* Analogue of print_hex_dump() */
+void seq_hex_dump(struct seq_file *m, 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;
+ int ret;
+
+ if (rowsize != 16 && rowsize != 32)
+ rowsize = 16;
+
+ for (i = 0; i < len; i += rowsize) {
+ linelen = min(remaining, rowsize);
+ remaining -= rowsize;
+
+ ret = seq_printf(m, "%s", prefix_str);
+ if (ret < 0)
+ break;
+
+ if (prefix_type == DUMP_PREFIX_ADDRESS)
+ ret = seq_printf(m, "%p: ", ptr + i);
+ else if (prefix_type == DUMP_PREFIX_OFFSET)
+ ret = seq_printf(m, "%.8x: ", i);
+ if (ret < 0)
+ break;
+
+ if (m->size < m->count + groupsize * 2 + 1)
+ break;
+
+ hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
+ m->buf + m->count, m->size - m->count,
+ ascii);
+
+ ret = seq_putc(m, '\n');
+ if (ret < 0)
+ break;
+ }
+}
+EXPORT_SYMBOL(seq_hex_dump);

--
Andy Shevchenko <andriy.shevchenko@intel.com>
Intel Finland Oy