Re: virtio: console: Barrier needed before dropping early_put_chars?

On Wed, 24 Feb 2010 03:40:22 am Amit Shah wrote:

Hey Rusty, Christian,

Christoph Hellwig asked why we don't need a barrier before this code in
virtcons_probe():

quoted

+     /* Start using the new console output. */
+     early_put_chars = NULL;
      return 0;

Since only s390 uses early_put_chars so far, you'd know why it's not
needed / why we're safe.

He's right, it's sloppy.

In practice the compiler checks for NULL and reuses the pointer, and we
have no problem if this is used a couple of times after the real console is
live.

The Right Way to do this is a lock in put_chars() and around this assignment.
But do we really want to bother?

Cheers,
Rusty.
-- 
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