Messages in this thread Patch in this message | | | Subject | Re: [PATCH 1/2] Introduce tty_unregister_ldisc() | From | Paul Fulghum <> | Date | Tue, 31 May 2005 22:38:08 -0500 |
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On Tue, 2005-05-31 at 17:28 -0500, Paul Fulghum wrote: > An unmodified ldisc driver (externally maintained) will continue to call > tty_register_ldisc with NULL, but the new behavior will be to set the > ldisc pointer to NULL but have LDISC_FLAG_DEFINED set.
I was partially wrong. After Alexey's patch, a NULL new_ldisc is accessed (not assigned) causing an oops. This is still not good behavior.
As for the refcount bug, this patch should fix it. Comments?
-- Paul Fulghum paulkf@microgate.com
--- linux-2.6.11/drivers/char/tty_io.c 2005-03-02 01:38:10.000000000 -0600 +++ b/drivers/char/tty_io.c 2005-05-31 22:10:41.000000000 -0500 @@ -262,16 +262,16 @@ int tty_register_ldisc(int disc, struct return -EINVAL; spin_lock_irqsave(&tty_ldisc_lock, flags); - if (new_ldisc) { + if ((tty_ldiscs[disc].flags & LDISC_FLAG_DEFINED) && + tty_ldiscs[disc].refcount) + ret = -EBUSY; + else if (new_ldisc) { tty_ldiscs[disc] = *new_ldisc; tty_ldiscs[disc].num = disc; tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED; tty_ldiscs[disc].refcount = 0; } else { - if(tty_ldiscs[disc].refcount) - ret = -EBUSY; - else - tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED; + tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED; } spin_unlock_irqrestore(&tty_ldisc_lock, flags);
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