Re: How to find out which part of code is changing a particular data structure.

From: Valdis.Kletnieks@vt.edu
To: kiran kumar <akirank@yahoo.com>
Cc: Rajat Jain <rajatjain@juniper.net>,
	"linux-newbie@vger.kernel.org" <linux-newbie@vger.kernel.org>,
	"kernelnewbies@kernelnewbies.org"
	<kernelnewbies@kernelnewbies.org>
Subject: Re: How to find out which part of code is changing a particular data structure.
Date: Fri, 08 Nov 2013 09:51:54 -0500	[thread overview]
Message-ID: <52596.1383922314@turing-police.cc.vt.edu> (raw)
In-Reply-To: Your message of "Thu, 07 Nov 2013 23:23:18 -0800." <1383895398.45469.YahooMailNeo@web142703.mail.bf1.yahoo.com>

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On Thu, 07 Nov 2013 23:23:18 -0800, kiran kumar said:
> Can you define that location as read only(i.e constant)?. This is only for
> debug prupose, later you can remove.

Note that this requires 2 things:

1) A kernel built with CONFIG_DEBUG_RODATA=y

2) The structure needs to have a compile-time initializer:

struct foo barbaz = { 5, 3, "quuz"};

Otherwise, your kernel will throw an oops when it tries to initialize
the structure at runtime (which is almost certainly *not* the time that
is causing the actual problem).

Simply declaring it as 'const struct' may or may not help - this will catch
at compile time lots of mistakes, but isn't guaranteed to stop all cases of
buggy uses of miscast pointers, etc....

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