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From: Miklos Szeredi <miklos@szeredi.hu>
Date: Thu, 8 Feb 2024 10:09:36 +0100
Message-ID: <CAJfpeguTGdAuQ+5Ai0ZXL7p-UeCyk2spBDhm6bkdTC-0UAKenQ@mail.gmail.com>
Subject: Re: [LSF/MM/BPF TOPIC] tracing the source of errors
To: Dave Chinner <david@fromorbit.com>
Cc: lsf-pc <lsf-pc@lists.linux-foundation.org>, linux-kernel@vger.kernel.org, 
	linux-fsdevel@vger.kernel.org
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On Wed, 7 Feb 2024 at 22:37, Dave Chinner <david@fromorbit.com> wrote:

> ftrace using the function_graph tracer will emit the return values
> of the functions if you use it with the 'funcgraph-retval' option.
>
> Seems like a solved problem?

Except

a) this seems exceedingly difficult to set up for non-developers,
which is often where this is needed.  Even strace is pretty verbose
and the generated output too big, let alone all function calls across
the whole system.

b) can only point to the function was generated.  But the same error
is often generated for several different reasons within the same
function and the return value doesn't help there.

I think a) is the critical one, and possibly the ftrace infrastructure
could be used for something more friendly that just pointed to the
function where the error was generated without having to go through
hoops.

Thanks,
Miklos