Re: [PATCH 00/26] Don't use stack for DMA transers on dvb-usb drivers

2016-10-11 Thread Mauro Carvalho Chehab 
Em Mon, 10 Oct 2016 07:44:53 -0400
Michael Ira Krufky  escreveu:

> Antti makes a very good point.  If we consider a situation where we
> are streaming data while concurrently checking frontend status and
> polling for IR codes, some locking will certainly be required in all
> of these drivers.
> 
> -Mike Krufky
> 
> On Mon, Oct 10, 2016 at 7:24 AM, Antti Palosaari  wrote:
> > Hello
> > If you use usb buffers from the state you will need add lock in order to
> > protect concurrent access to buffer. There may have multiple concurrent
> > operations from rc-polling/demux/frontend. Lets say you are reading ber and
> > it sets data to buffer (state), then context switch to remote controller
> > polling => buffer in state is overwritten, then context is changed back to
> > ber reading and now there is bad data.

Indeed a mutex to protect it is required. I added it and re-submitted
the series, with a few extra patches, fixing issues on some drivers
that are outside dvb-usb.

Feel free to review.

Regards,
Mauro
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Re: [PATCH 00/26] Don't use stack for DMA transers on dvb-usb drivers

2016-10-10 Thread Antti Palosaari 

Hello
If you use usb buffers from the state you will need add lock in order to 
protect concurrent access to buffer. There may have multiple concurrent 
operations from rc-polling/demux/frontend. Lets say you are reading ber 
and it sets data to buffer (state), then context switch to remote 
controller polling => buffer in state is overwritten, then context is 
changed back to ber reading and now there is bad data.


regards
Antti


On 10/07/2016 08:24 PM, Mauro Carvalho Chehab wrote:

Sending URB control messages from stack was never supported. Yet, on x86,
the stack was usually at a memory region that allows DMA transfer.

So, several drivers got it wrong. On Kernel 4.9, if VMAP_STACK=y, none of
those drivers will work, as the stack won't be on a DMA-able area anymore.

So, fix the dvb-usb drivers that requre it.

Please notice that, while all those patches compile, I don't have devices
using those drivers to test. So, I really appreciate if people with devices
using those drivers could test and report if they don't break anything.

Thanks!
Mauro

Mauro Carvalho Chehab (26):
  af9005: don't do DMA on stack
  cinergyT2-core: don't do DMA on stack
  cinergyT2-core:: handle error code on RC query
  cinergyT2-fe: cache stats at cinergyt2_fe_read_status()
  cinergyT2-fe: don't do DMA on stack
  cxusb: don't do DMA on stack
  dib0700: be sure that dib0700_ctrl_rd() users can do DMA
  dib0700_core: don't use stack on I2C reads
  dibusb: don't do DMA on stack
  dibusb: handle error code on RC query
  digitv: don't do DMA on stack
  dtt200u-fe: don't do DMA on stack
  dtt200u-fe: handle errors on USB control messages
  dtt200u: don't do DMA on stack
  dtt200u: handle USB control message errors
  dtv5100: : don't do DMA on stack
  gp8psk: don't do DMA on stack
  gp8psk: don't go past the buffer size
  nova-t-usb2: don't do DMA on stack
  pctv452e: don't do DMA on stack
  pctv452e: don't call BUG_ON() on non-fatal error
  technisat-usb2: use DMA buffers for I2C transfers
  dvb-usb: warn if return value for USB read/write routines is not
checked
  nova-t-usb2: handle error code on RC query
  dw2102: return error if su3000_power_ctrl() fails
  digitv: handle error code on RC query

 drivers/media/usb/dvb-usb/af9005.c  | 211 +++-
 drivers/media/usb/dvb-usb/cinergyT2-core.c  |  52 ---
 drivers/media/usb/dvb-usb/cinergyT2-fe.c|  91 
 drivers/media/usb/dvb-usb/cxusb.c   |  20 +--
 drivers/media/usb/dvb-usb/cxusb.h   |   5 +
 drivers/media/usb/dvb-usb/dib0700_core.c|  31 +++-
 drivers/media/usb/dvb-usb/dib0700_devices.c |  25 ++--
 drivers/media/usb/dvb-usb/dibusb-common.c   | 112 +++
 drivers/media/usb/dvb-usb/dibusb.h  |   5 +
 drivers/media/usb/dvb-usb/digitv.c  |  26 ++--
 drivers/media/usb/dvb-usb/digitv.h  |   3 +
 drivers/media/usb/dvb-usb/dtt200u-fe.c  |  90 
 drivers/media/usb/dvb-usb/dtt200u.c |  80 +++
 drivers/media/usb/dvb-usb/dtv5100.c |  10 +-
 drivers/media/usb/dvb-usb/dvb-usb.h |   6 +-
 drivers/media/usb/dvb-usb/dw2102.c  |   2 +-
 drivers/media/usb/dvb-usb/gp8psk.c  |  25 +++-
 drivers/media/usb/dvb-usb/nova-t-usb2.c |  25 +++-
 drivers/media/usb/dvb-usb/pctv452e.c| 118 
 drivers/media/usb/dvb-usb/technisat-usb2.c  |  16 ++-
 20 files changed, 577 insertions(+), 376 deletions(-)



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[PATCH 00/26] Don't use stack for DMA transers on dvb-usb drivers

2016-10-07 Thread Mauro Carvalho Chehab 
Sending URB control messages from stack was never supported. Yet, on x86,
the stack was usually at a memory region that allows DMA transfer.

So, several drivers got it wrong. On Kernel 4.9, if VMAP_STACK=y, none of
those drivers will work, as the stack won't be on a DMA-able area anymore.

So, fix the dvb-usb drivers that requre it.

Please notice that, while all those patches compile, I don't have devices
using those drivers to test. So, I really appreciate if people with devices
using those drivers could test and report if they don't break anything.

Thanks!
Mauro

Mauro Carvalho Chehab (26):
  af9005: don't do DMA on stack
  cinergyT2-core: don't do DMA on stack
  cinergyT2-core:: handle error code on RC query
  cinergyT2-fe: cache stats at cinergyt2_fe_read_status()
  cinergyT2-fe: don't do DMA on stack
  cxusb: don't do DMA on stack
  dib0700: be sure that dib0700_ctrl_rd() users can do DMA
  dib0700_core: don't use stack on I2C reads
  dibusb: don't do DMA on stack
  dibusb: handle error code on RC query
  digitv: don't do DMA on stack
  dtt200u-fe: don't do DMA on stack
  dtt200u-fe: handle errors on USB control messages
  dtt200u: don't do DMA on stack
  dtt200u: handle USB control message errors
  dtv5100: : don't do DMA on stack
  gp8psk: don't do DMA on stack
  gp8psk: don't go past the buffer size
  nova-t-usb2: don't do DMA on stack
  pctv452e: don't do DMA on stack
  pctv452e: don't call BUG_ON() on non-fatal error
  technisat-usb2: use DMA buffers for I2C transfers
  dvb-usb: warn if return value for USB read/write routines is not
checked
  nova-t-usb2: handle error code on RC query
  dw2102: return error if su3000_power_ctrl() fails
  digitv: handle error code on RC query

 drivers/media/usb/dvb-usb/af9005.c  | 211 +++-
 drivers/media/usb/dvb-usb/cinergyT2-core.c  |  52 ---
 drivers/media/usb/dvb-usb/cinergyT2-fe.c|  91 
 drivers/media/usb/dvb-usb/cxusb.c   |  20 +--
 drivers/media/usb/dvb-usb/cxusb.h   |   5 +
 drivers/media/usb/dvb-usb/dib0700_core.c|  31 +++-
 drivers/media/usb/dvb-usb/dib0700_devices.c |  25 ++--
 drivers/media/usb/dvb-usb/dibusb-common.c   | 112 +++
 drivers/media/usb/dvb-usb/dibusb.h  |   5 +
 drivers/media/usb/dvb-usb/digitv.c  |  26 ++--
 drivers/media/usb/dvb-usb/digitv.h  |   3 +
 drivers/media/usb/dvb-usb/dtt200u-fe.c  |  90 
 drivers/media/usb/dvb-usb/dtt200u.c |  80 +++
 drivers/media/usb/dvb-usb/dtv5100.c |  10 +-
 drivers/media/usb/dvb-usb/dvb-usb.h |   6 +-
 drivers/media/usb/dvb-usb/dw2102.c  |   2 +-
 drivers/media/usb/dvb-usb/gp8psk.c  |  25 +++-
 drivers/media/usb/dvb-usb/nova-t-usb2.c |  25 +++-
 drivers/media/usb/dvb-usb/pctv452e.c| 118 
 drivers/media/usb/dvb-usb/technisat-usb2.c  |  16 ++-
 20 files changed, 577 insertions(+), 376 deletions(-)

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