From: Andrew Morton <akpm@linux-foundation.org>
To: Joe Perches <joe@perches.com>
Cc: jengelh@computergmbh.de, randy.dunlap@oracle.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Reduce stack used by lib/hexdump.c
Date: Wed, 5 Dec 2007 16:01:33 -0800 [thread overview]
Message-ID: <20071205160133.0766c4f5.akpm@linux-foundation.org> (raw)
In-Reply-To: <1196378922.22120.72.camel@localhost>
On Thu, 29 Nov 2007 15:28:42 -0800
Joe Perches <joe@perches.com> wrote:
> 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;
> + }
No, I think print_hex_dump() is too low-level to be doing allocations.
For example, one could easily choose to call print_hex_dump() at oops time,
and then what happens if we oops in kmalloc() (as we often do...)?
You could trim linebuf[] to 80 chars or so. Extra points for making it
very clear when someone tries to exceed that - strcpy(linebuf, "stop being
stupid").
next prev parent reply other threads:[~2007-12-06 0:02 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-29 18:08 [PATCH] Remove #define hex_asc from kernel.h, update lib/hexdump.c Joe Perches
2007-11-29 18:24 ` Randy Dunlap
2007-11-29 18:44 ` Joe Perches
2007-11-29 18:52 ` Randy Dunlap
2007-11-29 18:55 ` Joe Perches
2007-11-29 20:57 ` [PATCH] Reduce stack used by lib/hexdump.c Joe Perches
2007-11-29 21:02 ` Randy Dunlap
2007-11-29 21:07 ` Jan Engelhardt
2007-11-29 23:28 ` Joe Perches
2007-12-06 0:01 ` Andrew Morton [this message]
2007-12-06 2:10 ` Joe Perches
2007-12-06 2:18 ` Randy Dunlap
2007-12-06 2:42 ` Joe Perches
2007-12-06 5:58 ` Kyle Moffett
2007-12-06 7:10 ` Andrew Morton
2007-12-06 21:52 ` Joe Perches
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20071205160133.0766c4f5.akpm@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=jengelh@computergmbh.de \
--cc=joe@perches.com \
--cc=linux-kernel@vger.kernel.org \
--cc=randy.dunlap@oracle.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).