linux-kernel - Re: [PATCH 1/2] seq_buf: Add printing formatted hex dumps

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Date:   Wed, 6 Nov 2019 11:34:20 +0200
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Piotr Maziarz <piotrx.maziarz@...ux.intel.com>,
        linux-kernel@...r.kernel.org, mingo@...hat.com,
        cezary.rojewski@...el.com, gustaw.lewandowski@...el.com
Subject: Re: [PATCH 1/2] seq_buf: Add printing formatted hex dumps

On Wed, Nov 06, 2019 at 03:53:17AM -0500, Steven Rostedt wrote:
> On Wed,  6 Nov 2019 07:27:39 +0100
> Piotr Maziarz <piotrx.maziarz@...ux.intel.com> wrote:

> > +	for (i = 0; i < len; i += rowsize) {
> > +		linelen = min(remaining, rowsize);
> > +		remaining -= rowsize;
> 
> Probably should make the above:
> 
> 		remaining -= linelen;
> 
> Yeah, what you have works, but it makes a reviewer worry about using
> remaining later and having it negative.

OTOH, the original function and followers (like seq_hex_dump() one) are using
exactly above form. Maybe for the sake of consistency we may do the same and
then fix all at once. Or other way around, amend the rest first.

> > +		case DUMP_PREFIX_ADDRESS:
> 
> I'm curious to know what uses the above type? By default, today,
> pointers are pretty much obfuscated, and that will show up here too.

Good question. Current users are:

arch/microblaze/kernel/traps.c
arch/x86/kernel/mpparse.c
drivers/crypto/axis/artpec6_crypto.c
drivers/crypto/caam/...
drivers/crypto/ccree/cc_driver.c
drivers/crypto/qat/qat_common/adf_transport_debug.c
drivers/dma/xgene-dma.c
drivers/mailbox/mailbox-test.c
drivers/net/can/usb/ucan.c
drivers/net/ethernet/cadence/macb_main.c
drivers/net/ethernet/cavium/liquidio/octeon_droq.c
drivers/net/ethernet/intel/...
drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
drivers/usb/gadget/function/f_ncm.c
fs/ext4/super.c
fs/jfs/...
mm/page_poison.c
mm/slub.c

Not many.

My understanding that it's still useful in conjunction with some other messages
where pointers are printed and developer, who is reading the logs, may match
them and do some conclusions.

> > +	}

-- 
With Best Regards,
Andy Shevchenko