Re: [RFC PATCH 0/2] avoid clobbering registers with J_ASSERT macro

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 17 Aug 2007 01:54:18 -0400
Chris Snook <csnook@redhat.com> wrote:

> The J_ASSERT() macro in jbd and jbd2 calls printk() prior to BUG().  While this 
> makes it more convenient to read the assertion failure, it also clobbers 
> registers, which can sometimes make debugging harder, which is clearly not the 
> intended purpose.  I recently banged my head on this myself.
> 
> The following patches to jbd and jbd2 enable the printk only if 
> CONFIG_JBD[2]_DEBUG is set.  Otherwise, it will simply BUG if the condition is 
> violated.  This way test kernels still get the benefit of the J_ASSERT printk, 
> while production kernels, which come from a more stable source base where it's 
> easier to trace line numbers back to specific lines of code, simply get the BUG, 
> with all registers preserved.
> 
> This is, of course, not the only way of fixing this problem, but it seems to be 
> the least invasive way, which is why I'm proposing these patches.

How's about we just remove that printk?  Do

#define J_ASSERT(e) BUG_ON(e)?

The rest of the kernel seems to be able to cope with that...