Re: [PATCH] Ref counting for tty_struct and some locking clean up

[Randy.Dunlap]

On Fri, 7 Jul 2006 20:37:36 -0400 Jon Smirl wrote:

> This patch removes tty_mutex and replaces it with a ref counted
> tty_struct. A new spinlock, tty_lock, serializes tty
> creation/destruction. This code thoroughly audits everyone taking
> references to tty_struct and tracks them. I have been running it
> locally for a few days without any issues.
> 
> If there is a refcount problem it will trigger a WARN_ON. If you hit
> one, defining DEBUG_TTY_REFCOUNT will provide plenty of debug info to
> help locate the missing reference. I definitely found multiple locking
> holes in the old tty_mutex code but they they look hard to hit.
> 
> This is just a first step, if this code proves to be stable I'll do
> another round of cleanup. There is room for a lot more work to be
> done. Ultimately there may not even be a need for a tty refcount if
> everything is locked correctly. But that is a big step and we should
> take some smaller ones first.
> 
> This is meant for mm until it gets some testing - I don't want to
> break anyone's console. If gmail wraps it let me know and I'll send
> you an attachment.

It has one wrapped line in it but does not apply cleanly to
2.6.18-rc1 or to 2.6.17-mm6.  What was it diffed against?

---
~Randy
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