cx18: Convert cx18_queue buffers member to atomic_t.  This allows safe
concurrent access to check if a queue has data without having to acquire the
queue spinlock.
Signed-off-by: NAndy Walls <awalls@radix.net>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

cx18: Remove redundant struct cx18_queue length member. It can be trivially
computed from queue->buffers * stream->buf_size, if ever really needed.
Signed-off-by: NAndy Walls <awalls@radix.net>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

cx18: Simplify queue flush logic to prevent oops in cx18_flush_queues().
If accounting of a queue is in error, logic borrowed from ivtv will cause
an oops when flushing the queues for a stream.  This change greatly
simplifies the queue flush logic, and sets the queue back to sane
defaults on a flush.
Signed-off-by: NAndy Walls <awalls@radix.net>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Fixed a lot of sparse warnings: mostly warnings about shadowed variables
and signed/unsigned mismatches.
Signed-off-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

cx18: Add missing lock for when the irq handler manipulates the queues.  This
was a potential source of stream queue corruption.  Also changed the name of
cx18_queue_find_buf() to cx18_queue_get_buf_irq().
Signed-off-by: NAndy Walls <awalls@radix.net>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

This patch contains the following possible cleanups:
- cx18-i2c.c should #include "cx18-i2c.h" for getting the prototypes of
  it's global functions
- make the following needlessly global functions static:
  - cx18-fileops.c:cx18_claim_stream()
  - cx18-fileops.c:cx18_release_stream()
  - cx18-queue.c:cx18_queue_move()
- remove the following unused functions:
  - cx18-driver.c:cx18_waitq()
  - cx18-queue.c:cx18_buf_copy_from_user()
Signed-off-by: NAdrian Bunk <bunk@kernel.org>
Reviewed-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

- don't show kernel backtrace when the allocation of the buffers fails: the
  normal ivtv/cx18 messages are clear enough and the backtrace scares users.
- fix cleanup after the buffer allocation fails (caused kernel panic).
Signed-off-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

Many thanks to Steve Toth from Hauppauge and Nattu Dakshinamurthy from
Conexant for their support. I am in particular thankful to Hauppauge
since without their help this driver would not exist. It should also
be noted that Steve did the work to get the DVB part up and running.
Thank you!
Signed-off-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NSteven Toth <stoth@hauppauge.com>
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NG. Andrew Walls <awalls@radix.net>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>