Messages in this thread | | | Date | Tue, 09 Sep 2008 07:15:12 -0600 | From | Joe Peterson <> | Subject | Re: [PATCH] TTY: Fix loss of echoed characters (2nd follow-on PATCH attached) |
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Alan Cox wrote: > If you have the column handling isolated and locked that is a big step > towards exterminating the BKL in the n_tty code. It also illustrates why > locking people always say "lock data not code".
Well, it's isolated, but still locked with the BKL, which would be great to get rid of. A few questions for you, since you've worked with this code (and kernel locking stuff) a lot longer than I:
1) Now that column state is confined to the process_out/echo funcs in n_tty, would using tty_write_lock() (the defined atomic write lock mutex) be a good replacement for lock_kernel(), even though interruptible?
2) To protect echo buffer operations, I would lean toward using a separate echo lock mutex so it does not lock against non-echo-buffer output. Would nesting this with #1 be advisable? Should it be interruptable?
3) tty_write() mentions refers to ldisc use of the BKL. If we change this, are there any considerations for the tty_io or driver code?
Thanks, Joe
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