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Subject: Re: [PATCH] Reduce stack used by lib/hexdump.c
From: Joe Perches <joe@perches.com>
To: Jan Engelhardt <jengelh@computergmbh.de>
Cc: Randy Dunlap <randy.dunlap@oracle.com>,
       linux-kernel <linux-kernel@vger.kernel.org>
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Date: Thu, 29 Nov 2007 15:28:42 -0800
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On Thu, 2007-11-29 at 22:07 +0100, Jan Engelhardt wrote:
> I'd add GFP_ATOMIC here. Who knows whether tomorrow, the oops dumper
> or warn_on will use print_hex_dump.

Signed-off-by: Joe Perches <joe@perches.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_ATOMIC);
+	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);