Make lots of structures const in order to make it obvious that they need no
locking.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch adds support for throttling and unthrottling input when the tty
driver can't handle it.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch simplifies the opening and closing of host console devices and the
registration and deregistration of IRQs.  The intent is to make it obvious
that an IRQ can't exist without an open file descriptor.

chan_enable will now open the channel, and when both opening and IRQ
registration are desired, this should be used.  Opening only is done for the
initial console, so that interface still needs to exist.

The free_irqs_later interface is now gone.  It was intended to avoid freeing
an IRQ while it was being processed.  It did this, but it didn't eliminate the
possiblity of free_irq being called from an interrupt, which is bad.  In its
place is a list of irqs to be freed, which is processed by the signal handler
just before exiting.  close_one_chan now disables irqs.

When a host device disappears, it is just closed, and that disables IRQs.

The device id registered with the IRQ is now the chan structure, not the tty.
This is because the interrupt arrives on a descriptor associated with the
channel.  This caused equivalent changes in the arguments to line_timer_cb.
line_disable is gone since it is not used any more.

The count field in the line structure is gone.  tty->count is used instead.

The complicated logic in sigio_handler with freeing IRQs when necessary and
making sure its idea of the next irq is correct is now much simpler.  The irq
list can't be rearranged underneath it, so it is now a simple list walk.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This removes a structure field which turned out to be pointless, and
references to it.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch makes a bunch of non-functional changes -
    return(foo); becomes return foo;
    some statements are broken across lines for readability
    some trailing whitespace is cleaned up
    open_one_chan took four arguments, three of which could be
       deduced from the first.  Accordingly, they were eliminated.
    some examples of "} else {" had a newline added
    some whitespace cleanup in the indentation
    lines_init got some control flow cleanup
    some long lines were broken
    removed another emacs-specific C formatting comment
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!