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 <crope@xxxxxx> 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. > > 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(-) >> > > -- > http://palosaari.fi/ > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
