Re: [PATCH v2] virtio: Add function name to error messages

["Daniel P. Berrangé" <berrange@redhat.com>]

On Mon, Sep 22, 2025 at 12:37:57PM +0200, Markus Armbruster wrote:
> Alessandro Ratti <alessandro@0x65c.net> writes:
> 
> > Replace virtio_error() with a macro that automatically prepends the
> > calling function name to error messages. This provides better context
> > for debugging virtio issues by showing exactly which function
> > encountered the error.
> >
> > Before: "Invalid queue size: 1024"
> > After:  "virtio_queue_set_num: Invalid queue size: 1024"
> >
> > The implementation uses a macro to insert __func__ at compile time,
> > avoiding any runtime overhead while providing more specific error
> > context than a generic "virtio:" prefix.
> 
> A need for function names and such in error messages suggests the error
> messages are crap.

I pretty much agree. If we take that view forwards, then I think our
coding guidelines should explicitly state something like

 "Function names must never be included in error messages.

  The messages need to be sufficiently descriptive in their
  text, such that including function names is redundant"

> > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/230

This is interesting as it shows a link to a previously proposed patch:

  https://patchwork.kernel.org/project/qemu-devel/patch/20220414112902.41390-1-codeguy.moteen@gmail.com/

this old patch just expanded the error messages to include 'Virtio '
in their text. I'm not going to claim this made new error messages
hugely user friendly, but I think that old patch approach was at
least conceptually better & preferrable to the function name
addition.

> > Buglink: https://bugs.launchpad.net/qemu/+bug/1919021
> >
> > Signed-off-by: Alessandro Ratti <alessandro@0x65c.net>

With regards,
Daniel
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