Revert "virtio_console: Initialize guest_connected=true for rproc_serial"

This reverts commit 8078db789a92b10ff6e2d713231b5367e014c53b, and
adds a lengthy comment explaining the problem area.

The reverted patch caused opening of ports to fail for rproc_serial.
In probe guest_connected was set to true, but port_fops_open()
fails with -EMFILE if guest_connected already is true.

Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
hw_random: free rng_buffer at module exit

rng-core module allocates rng_buffer by kmalloc() since commit
f7f154f1246ccc5a0a7e9ce50932627d60a0c878. But this buffer won't be
freed and there is a memory leak possibility at module exit.

Signed-off-by: Satoru Takeuchi <satoru.takeuchi@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
virtio: console: rename cvq_lock to c_ivq_lock

The cvq_lock was taken for the c_ivq.  Rename the lock to make that
obvious.

We'll also add a lock around the c_ovq in the next commit, so there's no
ambiguity.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Asias He <asias@redhat.com>
Reviewed-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
virtio: console: add locking around c_ovq operations

When multiple ovq operations are being performed (lots of open/close
operations on virtio_console fds), the __send_control_msg() function can
get confused without locking.

A simple recipe to cause badness is:
* create a QEMU VM with two virtio-serial ports
* in the guest, do
  while true;do echo abc >/dev/vport0p1;done
  while true;do echo edf >/dev/vport0p2;done

In one run, this caused a panic in __send_control_msg().  In another, I
got

   virtio_console virtio0: control-o:id 0 is not a head!

This also results repeated messages similar to these on the host:

  qemu-kvm: virtio-serial-bus: Unexpected port id 478762112 for device virtio-serial-bus.0
  qemu-kvm: virtio-serial-bus: Unexpected port id 478762368 for device virtio-serial-bus.0

Reported-by: FuXiangChun <xfu@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Reviewed-by: Asias He <asias@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
Merge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

Pull virtio fixes from Rusty Russell:
 "One reversion, a tiny leak fix, and a cc:stable locking fix, in two
  parts"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  virtio: console: add locking around c_ovq operations
  virtio: console: rename cvq_lock to c_ivq_lock
  hw_random: free rng_buffer at module exit
  Revert "virtio_console: Initialize guest_connected=true for rproc_serial"