linux-toradex.git/drivers/char/virtio_console.c, branch v2.6.35

virtio: console: Fix crash when port is unplugged and blocked for write

2010-06-03T13:09:19+00:00

When a program that has a virtio port opened and blocked for a write
operation, a port hot-unplug event will later led to a crash when
SIGTERM was sent to the program. Fix that.

Signed-off-by: Amit Shah 
Signed-off-by: Rusty Russell

virtio: console: Fix crash when hot-unplugging a port and read is blocked

2010-06-03T13:09:18+00:00

When removing a port we don't check if a program was blocked for read.
This leads to a crash when SIGTERM is sent to the program after
hot-unplugging the port.

Signed-off-by: Amit Shah 
Signed-off-by: Rusty Russell

drivers/char: Eliminate use after free

2010-05-19T12:45:51+00:00

In each case, the first argument to send_control_msg or __send_control_msg,
respectively, has either not been successfully allocated or has been freed
at the point of the call.  In the first case, the first argument, port, is
only used to access the portdev and id fields, in order to call
__send_control_msg.  Thus it seems possible instead to call
__send_control_msg directly.  In the second case, the call to
__send_control_msg is moved up to a place where it seems like the first
argument, portdev, has been initialized sufficiently to make the call to
__send_control_msg meaningful.

This has only been compile tested.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// 
@free@
expression E;
position p;
@@
kfree@p(E)

@@
expression free.E, subE<=free.E, E1;
position free.p;
@@

  kfree@p(E)
  ...
(
  subE = E1
|
* E
)
// 

Signed-off-by: Julia Lawall 
Acked-by: Amit Shah 
Signed-off-by: Rusty Russell

virtio: console: Accept console size along with resize control message

2010-05-19T12:45:51+00:00

The VIRTIO_CONSOLE_RESIZE control message sent to us by the host now
contains the new {rows, cols} values for the console. This ensures each
console port gets its own size, and we don't depend on the config-space
rows and cols values at all now.

Signed-off-by: Amit Shah 
CC: Christian Borntraeger 
CC: linuxppc-dev@ozlabs.org
CC: Kusanagi Kouichi 
Signed-off-by: Rusty Russell

virtio: console: Store each console's size in the console structure

2010-05-19T12:45:51+00:00

With support for multiple consoles, just using one {rows,cols} pair in
the config space is not going to suffice.

Store each console's size as part of the console struct.

This changes the behaviour for one case when multiport is not enabled:
when notifier_add_vio() is called, the console size is taken from that
of the last config-space update instead of fetching it afresh from the
config space.

Also add a helper to update the size in the console struct as we'll need
to use the same code to update the size via control messages when
multiport support is enabled.

Signed-off-by: Amit Shah 
CC: Christian Borntraeger 
CC: linuxppc-dev@ozlabs.org
CC: Kusanagi Kouichi 
Signed-off-by: Rusty Russell

virtio: console: Resize console port 0 on config intr only if multiport is off

2010-05-19T12:45:50+00:00

When using multiport, we'll use control messages. Ensure we don't
accidentally update port 0 size on config interrupts.

Signed-off-by: Amit Shah 
CC: Christian Borntraeger 
CC: linuxppc-dev@ozlabs.org
CC: Kusanagi Kouichi 
Signed-off-by: Rusty Russell

virtio: console: Add support for nonblocking write()s

2010-05-19T12:45:50+00:00

If the host port is not open, a write() should either just return if the
file is opened in non-blocking mode, or block till the host port is
opened.

Also, don't spin till host consumes data for nonblocking ports. For
non-blocking ports, we can do away with the spinning and reclaim the
buffers consumed by the host on the next write call or on the condition
that'll make poll return.

Signed-off-by: Amit Shah 
Signed-off-by: Rusty Russell

virtio: console: Rename wait_is_over() to will_read_block()

2010-05-19T12:45:50+00:00

We'll introduce a function that checks if write will block.  Have
function names that are similar for the two cases.

Signed-off-by: Amit Shah 
Signed-off-by: Rusty Russell

virtio: console: Don't always create a port 0 if using multiport

2010-05-19T12:45:49+00:00

If we're using multiport, there's no point in always creating a console
port. Create the console port only if the host doesn't support
multiport.

Signed-off-by: Amit Shah 
Signed-off-by: Rusty Russell

virtio: console: Use a control message to add ports

2010-05-19T12:45:49+00:00

Instead of the host and guest independently enumerating ports, switch to
a control message to add ports where the host supplies the port number
so there's no ambiguity or a possibility of a race between the host and
the guest port numbers.

We now no longer need the 'nr_ports' config value. Since no kernel has
been released with the MULTIPORT changes yet, we have a chance to fiddle
with the config space without adding compatibility features.

This is beneficial for management software, which would now be able to
instantiate ports at known locations and avoid problems that arise with
implicit numbering in the host and the guest. This removes the 'guessing
game' part of it, and management software can now actually indicate
which id to spawn a particular port on.

Signed-off-by: Amit Shah 
Signed-off-by: Rusty Russell