linux-kernel - Re: [Lsf-pc] [LSF/MM/BPF TOPIC] tracing the source of errors

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Message-ID: <ZcNw-ek8s3AHxxCB@casper.infradead.org>
Date: Wed, 7 Feb 2024 12:00:57 +0000
From: Matthew Wilcox <willy@...radead.org>
To: Miklos Szeredi <miklos@...redi.hu>
Cc: Jan Kara <jack@...e.cz>, lsf-pc <lsf-pc@...ts.linux-foundation.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [Lsf-pc] [LSF/MM/BPF TOPIC] tracing the source of errors

On Wed, Feb 07, 2024 at 12:23:41PM +0100, Miklos Szeredi wrote:
> On Wed, 7 Feb 2024 at 12:00, Jan Kara <jack@...e.cz> wrote:
> 
> > The problem always has been how to implement this functionality in a
> > transparent way so the code does not become a mess. So if you have some
> > idea, I'd say go for it :)
> 
> My first idea would be to wrap all instances of E* (e.g. ERR(E*)).
> But this could be made completely transparent by renaming current
> definition of E* to _E* and defining E* to be the wrapped ones.
> There's probably a catch (or several catches) somewhere, though.

To be perfectly clear, you're suggesting two things.

Option (a) change "all" code like this:
-	ret = -EINVAL;
+	ret = -ERR(EINVAL);

where ERR would do some magic with __func__ and __LINE__.

Option (b)

-#define EINVAL		22
+#define E_INVAL	22
+#define EINVAL		ERR(E_INVAL)

and then change all code that does something like:

	if (err == -EINVAL)
to
	if (err == -E_INVAL)

Or have I misunderstood?