Re: [LSF/MM/BPF TOPIC] tracing the source of errors

[Dave Chinner <david@fromorbit.com>]

On Wed, Feb 07, 2024 at 10:54:34AM +0100, Miklos Szeredi wrote:
> [I'm not planning to attend LSF this year, but I thought this topic
> might be of interest to those who will.]
> 
> The errno thing is really ancient and yet quite usable.  But when
> trying to find out where a particular EINVAL is coming from, that's
> often mission impossible.
> 
> Would it make sense to add infrastructure to allow tracing the source
> of errors?  E.g.
> 
> strace --errno-trace ls -l foo
> ...
> statx(AT_FDCWD, "foo", ...) = -1 ENOENT [fs/namei.c:1852]
> ...
> 
> Don't know about others, but this issue comes up quite often for me.

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?

-Dave.
-- 
Dave Chinner
david@fromorbit.com