Implement memory barriers according to Documentation/circular-buffers.txt:
- use smp_store_release() to update ringbuffer read/write pointers
- use smp_load_acquire() to load write pointer on reader side
- use ACCESS_ONCE() to load read pointer on writer side
This fixes data stream corruptions observed e.g. on an ARM Cortex-A9
quad core system with different types (PCI, USB) of DVB tuners.
Signed-off-by: Soeren Moch <smoch@web.de>
Cc: stable@vger.kernel.org # 3.14+
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Sparse is complaining about ngene's bad usage of a __user ptr:
>> drivers/media/pci/ngene/ngene-dvb.c:62:48: sparse: incorrect type in argument 2 (different address spaces)
drivers/media/pci/ngene/ngene-dvb.c:62:48: expected unsigned char const [usertype] *buf
drivers/media/pci/ngene/ngene-dvb.c:62:48: got char const [noderef] <asn:1>*buf
As this is intercepting a .write() file ops, we can't just memcpy. We need to use
copy_from_user.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
just like the V4L2 core, move the DVB core to drivers/media, as the
intention is to get rid of both "video" and "dvb" directories.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Soeren Moch