Re: [PATCH v10 1/1] virtio_console: Add support for multiple ports for generic guest and host communication

From: Rusty Russell
Date: Fri Nov 06 2009 - 02:10:17 EST

On Wed, 4 Nov 2009 03:08:39 am Amit Shah wrote:
> Expose multiple char devices ("ports") for simple communication
> between the host userspace and guest.

OK, I've taken the chance to audit this patch. I started adding patches
until I got overwhelmed. It's a complete mess and needs a total rewrite :(

This shows the problem with feeding me a complete driver rewrite in one
big hit. You've combined lots of changes and techniques in here at once:

1) Moved work out of interrupt handlers and into work_struct.
2) Encapsulated the buffer information in a structure.
3) Added an optional header to the buffer(s).
4) Added control messages.
5) Encapsulated the per-port information into a structure.
6) Allocated a static buffer pool of over 4MB (!)
7) Added an ad-hoc throttling mechanism.
8) Added debugfs support.

Less important nitpicks:
1) Don't call a struct list_head 'next', it confused the crap out of me.
Call it list or some other non-name.
2) Don't call control messages "internal". Use ONE good name, ie. control.
3) Don't use list_for_each_safe() to get the head entry of a list. Your
use is buggy anyway: buf will never be NULL afterwards.

In summary: this is the one we're going to throw away.

Now I'm going to start again, one patch at a time, and see how that works.

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