| Message ID | 20150208224422.GA22749@turing (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Feb 08, 2015 at 10:44:22PM +0000, Luis de Bethencourt wrote: > Cleaning the following compiler warning: > rtl2832.c:703:12: warning: 'tmp' may be used uninitialized in this function > > Even though it could never happen since if rtl2832_rd_demod_reg () doesn't set > tmp, this line would never run because we go to err. It is still nice to avoid > compiler warnings. > > Signed-off-by: Luis de Bethencourt <luis.bg@samsung.com> > --- > drivers/media/dvb-frontends/rtl2832.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/media/dvb-frontends/rtl2832.c b/drivers/media/dvb-frontends/rtl2832.c > index 5d2d8f4..ad36d1c 100644 > --- a/drivers/media/dvb-frontends/rtl2832.c > +++ b/drivers/media/dvb-frontends/rtl2832.c > @@ -685,7 +685,7 @@ static int rtl2832_read_status(struct dvb_frontend *fe, fe_status_t *status) > struct rtl2832_dev *dev = fe->demodulator_priv; > struct i2c_client *client = dev->client; > int ret; > - u32 tmp; > + u32 tmp = 0; > > dev_dbg(&client->dev, "\n"); > > -- > 2.1.0 > Hello all :) This warning can be seen in: http://hverkuil.home.xs4all.nl/logs/Saturday.log Thank you Hans for the daily build and logs. Luis -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 02/09/2015 12:44 AM, Luis de Bethencourt wrote: > Cleaning the following compiler warning: > rtl2832.c:703:12: warning: 'tmp' may be used uninitialized in this function > > Even though it could never happen since if rtl2832_rd_demod_reg () doesn't set > tmp, this line would never run because we go to err. It is still nice to avoid > compiler warnings. > > Signed-off-by: Luis de Bethencourt <luis.bg@samsung.com> > --- > drivers/media/dvb-frontends/rtl2832.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/media/dvb-frontends/rtl2832.c b/drivers/media/dvb-frontends/rtl2832.c > index 5d2d8f4..ad36d1c 100644 > --- a/drivers/media/dvb-frontends/rtl2832.c > +++ b/drivers/media/dvb-frontends/rtl2832.c > @@ -685,7 +685,7 @@ static int rtl2832_read_status(struct dvb_frontend *fe, fe_status_t *status) > struct rtl2832_dev *dev = fe->demodulator_priv; > struct i2c_client *client = dev->client; > int ret; > - u32 tmp; > + u32 tmp = 0; > > dev_dbg(&client->dev, "\n"); I looked the code and I cannot see how it could used as uninitialized. Dunno how it could be fixed properly. Also, I think idiom to say compiler that variable could be uninitialized is to store its own value. But I am fine with zero initialization too. u32 tmp = tmp; regards Antti
On Tue, Feb 10, 2015 at 12:57:24PM +0200, Antti Palosaari wrote: > On 02/09/2015 12:44 AM, Luis de Bethencourt wrote: > >Cleaning the following compiler warning: > >rtl2832.c:703:12: warning: 'tmp' may be used uninitialized in this function > > > >Even though it could never happen since if rtl2832_rd_demod_reg () doesn't set > >tmp, this line would never run because we go to err. It is still nice to avoid > >compiler warnings. > > > >Signed-off-by: Luis de Bethencourt <luis.bg@samsung.com> > >--- > > drivers/media/dvb-frontends/rtl2832.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > >diff --git a/drivers/media/dvb-frontends/rtl2832.c b/drivers/media/dvb-frontends/rtl2832.c > >index 5d2d8f4..ad36d1c 100644 > >--- a/drivers/media/dvb-frontends/rtl2832.c > >+++ b/drivers/media/dvb-frontends/rtl2832.c > >@@ -685,7 +685,7 @@ static int rtl2832_read_status(struct dvb_frontend *fe, fe_status_t *status) > > struct rtl2832_dev *dev = fe->demodulator_priv; > > struct i2c_client *client = dev->client; > > int ret; > >- u32 tmp; > >+ u32 tmp = 0; > > > > dev_dbg(&client->dev, "\n"); > > I looked the code and I cannot see how it could used as uninitialized. Dunno > how it could be fixed properly. Hi Antti, I agree. If rtl2832_rd_demod_reg() in line 696 doesn't set tmp it is because it has errored out. Which means rtl2832_read_status() itself will goto err before the check for 'if (tmp == 11)' line that generates the warning. I mentioned this in my commit message :) > > Also, I think idiom to say compiler that variable could be uninitialized is > to store its own value. But I am fine with zero initialization too. > > u32 tmp = tmp; > > regards > Antti > > -- > http://palosaari.fi/ If you prefer I use the 'u32 tmp = tmp;' I am happy to change my patch. You say you are fine with zero initialization too, but I prefer offering whatever you think is best. Thanks for taking the time to look at this, Luis -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Em Tue, 10 Feb 2015 12:57:24 +0200 Antti Palosaari <crope@iki.fi> escreveu: > On 02/09/2015 12:44 AM, Luis de Bethencourt wrote: > > Cleaning the following compiler warning: > > rtl2832.c:703:12: warning: 'tmp' may be used uninitialized in this function > > > > Even though it could never happen since if rtl2832_rd_demod_reg () doesn't set > > tmp, this line would never run because we go to err. It is still nice to avoid > > compiler warnings. > > > > Signed-off-by: Luis de Bethencourt <luis.bg@samsung.com> > > --- > > drivers/media/dvb-frontends/rtl2832.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/media/dvb-frontends/rtl2832.c b/drivers/media/dvb-frontends/rtl2832.c > > index 5d2d8f4..ad36d1c 100644 > > --- a/drivers/media/dvb-frontends/rtl2832.c > > +++ b/drivers/media/dvb-frontends/rtl2832.c > > @@ -685,7 +685,7 @@ static int rtl2832_read_status(struct dvb_frontend *fe, fe_status_t *status) > > struct rtl2832_dev *dev = fe->demodulator_priv; > > struct i2c_client *client = dev->client; > > int ret; > > - u32 tmp; > > + u32 tmp = 0; > > > > dev_dbg(&client->dev, "\n"); > > I looked the code and I cannot see how it could used as uninitialized. > Dunno how it could be fixed properly. > > Also, I think idiom to say compiler that variable could be uninitialized > is to store its own value. But I am fine with zero initialization too. > > u32 tmp = tmp; Actually, the right way is to declare it as: u32 uninitialized_var(tmp) The syntax to suppress compiler warnings depends on the compiler: include/linux/compiler-clang.h:#define uninitialized_var(x) x = *(&(x)) include/linux/compiler-gcc.h:#define uninitialized_var(x) x = x Also, using uninitialized_var() better documents it. Regards, Mauro -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Feb 10, 2015 at 09:35:52PM -0200, Mauro Carvalho Chehab wrote: > Em Tue, 10 Feb 2015 12:57:24 +0200 > Antti Palosaari <crope@iki.fi> escreveu: > > > On 02/09/2015 12:44 AM, Luis de Bethencourt wrote: > > > Cleaning the following compiler warning: > > > rtl2832.c:703:12: warning: 'tmp' may be used uninitialized in this function > > > > > > Even though it could never happen since if rtl2832_rd_demod_reg () doesn't set > > > tmp, this line would never run because we go to err. It is still nice to avoid > > > compiler warnings. > > > > > > Signed-off-by: Luis de Bethencourt <luis.bg@samsung.com> > > > --- > > > drivers/media/dvb-frontends/rtl2832.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/media/dvb-frontends/rtl2832.c b/drivers/media/dvb-frontends/rtl2832.c > > > index 5d2d8f4..ad36d1c 100644 > > > --- a/drivers/media/dvb-frontends/rtl2832.c > > > +++ b/drivers/media/dvb-frontends/rtl2832.c > > > @@ -685,7 +685,7 @@ static int rtl2832_read_status(struct dvb_frontend *fe, fe_status_t *status) > > > struct rtl2832_dev *dev = fe->demodulator_priv; > > > struct i2c_client *client = dev->client; > > > int ret; > > > - u32 tmp; > > > + u32 tmp = 0; > > > > > > dev_dbg(&client->dev, "\n"); > > > > I looked the code and I cannot see how it could used as uninitialized. > > Dunno how it could be fixed properly. > > > > Also, I think idiom to say compiler that variable could be uninitialized > > is to store its own value. But I am fine with zero initialization too. > > > > u32 tmp = tmp; > > Actually, the right way is to declare it as: > > u32 uninitialized_var(tmp) > > The syntax to suppress compiler warnings depends on the compiler: > > include/linux/compiler-clang.h:#define uninitialized_var(x) x = *(&(x)) > include/linux/compiler-gcc.h:#define uninitialized_var(x) x = x > > Also, using uninitialized_var() better documents it. > > Regards, > Mauro Hi Mauro, That is a way more elegant solution. Great! I will check out that compiler-clang header file, it's interesting. I just sent a revised patch using this :) Thanks, Luis -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/media/dvb-frontends/rtl2832.c b/drivers/media/dvb-frontends/rtl2832.c index 5d2d8f4..ad36d1c 100644 --- a/drivers/media/dvb-frontends/rtl2832.c +++ b/drivers/media/dvb-frontends/rtl2832.c @@ -685,7 +685,7 @@ static int rtl2832_read_status(struct dvb_frontend *fe, fe_status_t *status) struct rtl2832_dev *dev = fe->demodulator_priv; struct i2c_client *client = dev->client; int ret; - u32 tmp; + u32 tmp = 0; dev_dbg(&client->dev, "\n");
Cleaning the following compiler warning: rtl2832.c:703:12: warning: 'tmp' may be used uninitialized in this function Even though it could never happen since if rtl2832_rd_demod_reg () doesn't set tmp, this line would never run because we go to err. It is still nice to avoid compiler warnings. Signed-off-by: Luis de Bethencourt <luis.bg@samsung.com> --- drivers/media/dvb-frontends/rtl2832.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)