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SubjectRe: [PATCH 1/7] Add assertion support with annotated oopsing
Date
Ingo Molnar <mingo@elte.hu> wrote:

> Looks useful, but i'd suggest to make this a variant of the standard
> BUG_ON()/WARN_ON() checks we already have, not an explicit assert().
>
> BUG_ON_VERBOSE() or such.

I personally prefer the positive check (ASSERT() saying that this expression
must be true) as opposed to the negative check (BUG_ON() saying that this must
be false). I find it easier to think about the logic (I expect value X to be
like this, value Y to be like that, etc.).

That said, I could make the base bit BUG_VERBOSE(FMT, ...) and wrap ASSERT*()
around that.

However, I'd _much_ rather make it so that I can post the "cut here" message
early - but, IIRC, Linus hated that idea.

> I find assert()'s inversion confusing when mixed with WARN_ON()/BUG_ON().

Why did we do it this way originally, rather than using assert, I wonder?
Especially since the concept of assert already exists in userspace.

> Likewise, the message of:
>
> ASSERTION FAILED at fs/dcache.c:863!
>
> is rather confusing to me (i never know how the condition printed is
> to be interpreted) - why not use the usual 'BUG: ...' message
> convention?

I don't see why it should be confusing. Something bad happened at file:line.

I could make it print "BUG" instead. That's a minor matter. The ASSERT
macros in patch 2 could then generate a report that looks like this:

------------[ cut here ]------------
kernel BUG at fs/fscache/main.c:109!
Assertion failed: 2 > c is false
invalid opcode: 0000 [#1] SMP
David


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