Hello Arnd, thanks for patch. it looks ok. Acked-by: Abylay Ospan <aospan@xxxxxxxx> 2016-07-13 16:42 GMT-04:00 Arnd Bergmann <arnd@xxxxxxxx>: > The addition of jump label support in dynamic_debug caused an unexpected > warning in exactly one file in the kernel: > > drivers/media/dvb-frontends/cxd2841er.c: In function 'cxd2841er_tune_tc': > include/linux/dynamic_debug.h:134:3: error: 'carrier_offset' may be used uninitialized in this function [-Werror=maybe-uninitialized] > __dynamic_dev_dbg(&descriptor, dev, fmt, \ > ^~~~~~~~~~~~~~~~~ > drivers/media/dvb-frontends/cxd2841er.c:3177:11: note: 'carrier_offset' was declared here > int ret, carrier_offset; > ^~~~~~~~~~~~~~ > > The problem seems to be that the compiler gets confused by the extra conditionals > in static_branch_unlikely, to the point where it can no longer keep track of > which branches have already been taken, and it doesn't realize that this variable > is now always initialized when it gets used. > > I have done lots of randconfig kernel builds and could not find any other file > with this behavior, so I assume it's a rare enough glitch that we don't need > to change the jump label support but instead just work around the warning in > the driver. > > To achieve that, I'm moving the check for the return value into the switch() > statement, which is an obvious transformation, but is enough to un-confuse > the compiler here. The resulting code is not as nice to read, but at > least we retain the behavior of warning if it gets changed to actually > access an uninitialized carrier offset value in the future. > > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > Fixes: (in linux-mm) "dynamic_debug: add jump label support" > --- > drivers/media/dvb-frontends/cxd2841er.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/media/dvb-frontends/cxd2841er.c b/drivers/media/dvb-frontends/cxd2841er.c > index 721fb074da7c..0639ca281a2c 100644 > --- a/drivers/media/dvb-frontends/cxd2841er.c > +++ b/drivers/media/dvb-frontends/cxd2841er.c > @@ -3223,20 +3223,28 @@ static int cxd2841er_tune_tc(struct dvb_frontend *fe, > ret = cxd2841er_get_carrier_offset_i( > priv, p->bandwidth_hz, > &carrier_offset); > + if (ret) > + return ret; > break; > case SYS_DVBT: > ret = cxd2841er_get_carrier_offset_t( > priv, p->bandwidth_hz, > &carrier_offset); > + if (ret) > + return ret; > break; > case SYS_DVBT2: > ret = cxd2841er_get_carrier_offset_t2( > priv, p->bandwidth_hz, > &carrier_offset); > + if (ret) > + return ret; > break; > case SYS_DVBC_ANNEX_A: > ret = cxd2841er_get_carrier_offset_c( > priv, &carrier_offset); > + if (ret) > + return ret; > break; > default: > dev_dbg(&priv->i2c->dev, > @@ -3244,8 +3252,6 @@ static int cxd2841er_tune_tc(struct dvb_frontend *fe, > __func__, priv->system); > return -EINVAL; > } > - if (ret) > - return ret; > dev_dbg(&priv->i2c->dev, "%s(): carrier offset %d\n", > __func__, carrier_offset); > p->frequency += carrier_offset; > -- > 2.9.0 > -- Abylay Ospan, NetUP Inc. http://www.netup.tv -- 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
