staging: wimax/i2400m: don't change the endianness of one byte variable
diff mbox series

Message ID 20210218092154.GA46388@LEGION
State Accepted
Commit 62964172d9c1178ed7015b0396628bbddd67bd4d
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Series
  • staging: wimax/i2400m: don't change the endianness of one byte variable
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Commit Message

Muhammad Usama Anjum Feb. 18, 2021, 9:21 a.m. UTC
It is wrong to change the endianness of a variable which has just one
byte size.

Sparse warnings fixed:
drivers/staging//wimax/i2400m/control.c:452:17: warning: cast to restricted __le32
drivers/staging//wimax/i2400m/control.c:452:17: warning: cast to restricted __le32
drivers/staging//wimax/i2400m/op-rfkill.c:159:14: warning: cast to restricted __le32
drivers/staging//wimax/i2400m/op-rfkill.c:160:14: warning: cast to restricted __le32

Signed-off-by: Muhammad Usama Anjum <musamaanjum@gmail.com>
---
 drivers/staging/wimax/i2400m/control.c   | 4 ++--
 drivers/staging/wimax/i2400m/op-rfkill.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

Comments

Greg KH Feb. 18, 2021, 9:40 a.m. UTC | #1
On Thu, Feb 18, 2021 at 02:21:54PM +0500, Muhammad Usama Anjum wrote:
> It is wrong to change the endianness of a variable which has just one
> byte size.
> 
> Sparse warnings fixed:
> drivers/staging//wimax/i2400m/control.c:452:17: warning: cast to restricted __le32
> drivers/staging//wimax/i2400m/control.c:452:17: warning: cast to restricted __le32
> drivers/staging//wimax/i2400m/op-rfkill.c:159:14: warning: cast to restricted __le32
> drivers/staging//wimax/i2400m/op-rfkill.c:160:14: warning: cast to restricted __le32
> 
> Signed-off-by: Muhammad Usama Anjum <musamaanjum@gmail.com>
> ---
>  drivers/staging/wimax/i2400m/control.c   | 4 ++--
>  drivers/staging/wimax/i2400m/op-rfkill.c | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/wimax/i2400m/control.c b/drivers/staging/wimax/i2400m/control.c
> index 1e270b2101e8..b6b2788af162 100644
> --- a/drivers/staging/wimax/i2400m/control.c
> +++ b/drivers/staging/wimax/i2400m/control.c
> @@ -452,8 +452,8 @@ void i2400m_report_state_parse_tlv(struct i2400m *i2400m,
>  		d_printf(2, dev, "%s: RF status TLV "
>  			 "found (0x%04x), sw 0x%02x hw 0x%02x\n",
>  			 tag, I2400M_TLV_RF_STATUS,
> -			 le32_to_cpu(rfss->sw_rf_switch),
> -			 le32_to_cpu(rfss->hw_rf_switch));
> +			 rfss->sw_rf_switch,
> +			 rfss->hw_rf_switch);

What do you mean by "one byte"?  This is a le32 sized variable, right?
If not, why isn't the le32_to_cpu() call complaining?

>  		i2400m_report_tlv_rf_switches_status(i2400m, rfss);
>  	}
>  	if (0 == i2400m_tlv_match(tlv, I2400M_TLV_MEDIA_STATUS, sizeof(*ms))) {
> diff --git a/drivers/staging/wimax/i2400m/op-rfkill.c b/drivers/staging/wimax/i2400m/op-rfkill.c
> index fbddf2e18c14..a159808f0ec2 100644
> --- a/drivers/staging/wimax/i2400m/op-rfkill.c
> +++ b/drivers/staging/wimax/i2400m/op-rfkill.c
> @@ -156,8 +156,8 @@ void i2400m_report_tlv_rf_switches_status(
>  	enum i2400m_rf_switch_status hw, sw;
>  	enum wimax_st wimax_state;
>  
> -	sw = le32_to_cpu(rfss->sw_rf_switch);
> -	hw = le32_to_cpu(rfss->hw_rf_switch);
> +	sw = rfss->sw_rf_switch;
> +	hw = rfss->hw_rf_switch;

Same here.

thanks,

greg k-h
Muhammad Usama Anjum Feb. 18, 2021, 9:54 a.m. UTC | #2
On Thu, 2021-02-18 at 10:40 +0100, Greg KH wrote:
> On Thu, Feb 18, 2021 at 02:21:54PM +0500, Muhammad Usama Anjum wrote:
> > It is wrong to change the endianness of a variable which has just one
> > byte size.
> > 
> > Sparse warnings fixed:
> > drivers/staging//wimax/i2400m/control.c:452:17: warning: cast to restricted __le32
> > drivers/staging//wimax/i2400m/control.c:452:17: warning: cast to restricted __le32
> > drivers/staging//wimax/i2400m/op-rfkill.c:159:14: warning: cast to restricted __le32
> > drivers/staging//wimax/i2400m/op-rfkill.c:160:14: warning: cast to restricted __le32
> > 
> > Signed-off-by: Muhammad Usama Anjum <musamaanjum@gmail.com>
> > ---
> >  drivers/staging/wimax/i2400m/control.c   | 4 ++--
> >  drivers/staging/wimax/i2400m/op-rfkill.c | 4 ++--
> >  2 files changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/staging/wimax/i2400m/control.c b/drivers/staging/wimax/i2400m/control.c
> > index 1e270b2101e8..b6b2788af162 100644
> > --- a/drivers/staging/wimax/i2400m/control.c
> > +++ b/drivers/staging/wimax/i2400m/control.c
> > @@ -452,8 +452,8 @@ void i2400m_report_state_parse_tlv(struct i2400m *i2400m,
> >  		d_printf(2, dev, "%s: RF status TLV "
> >  			 "found (0x%04x), sw 0x%02x hw 0x%02x\n",
> >  			 tag, I2400M_TLV_RF_STATUS,
> > -			 le32_to_cpu(rfss->sw_rf_switch),
> > -			 le32_to_cpu(rfss->hw_rf_switch));
> > +			 rfss->sw_rf_switch,
> > +			 rfss->hw_rf_switch);
> 
> What do you mean by "one byte"?  This is a le32 sized variable, right?
> If not, why isn't the le32_to_cpu() call complaining?

These two variables are of type _u8, one byte. 
	__u8 sw_rf_switch;
	__u8 hw_rf_switch;
They aren't of type __le32. le32_to_cpu() macro should have
complained. But it isn't complaining. It seems like whatever we pass
to this macro, it casts it to __le32 forcefully (it seems like wrong).
So we'll never get any complain from this macro directly. But we are
getting complain from the sparse.

For big endian:
#define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
For little endian:
#define __le32_to_cpu(x) ((__force __u32)(__le32)(x))

> >  		i2400m_report_tlv_rf_switches_status(i2400m, rfss);
> >  	}
> >  	if (0 == i2400m_tlv_match(tlv, I2400M_TLV_MEDIA_STATUS, sizeof(*ms))) {
> > diff --git a/drivers/staging/wimax/i2400m/op-rfkill.c b/drivers/staging/wimax/i2400m/op-rfkill.c
> > index fbddf2e18c14..a159808f0ec2 100644
> > --- a/drivers/staging/wimax/i2400m/op-rfkill.c
> > +++ b/drivers/staging/wimax/i2400m/op-rfkill.c
> > @@ -156,8 +156,8 @@ void i2400m_report_tlv_rf_switches_status(
> >  	enum i2400m_rf_switch_status hw, sw;
> >  	enum wimax_st wimax_state;
> >  
> > -	sw = le32_to_cpu(rfss->sw_rf_switch);
> > -	hw = le32_to_cpu(rfss->hw_rf_switch);
> > +	sw = rfss->sw_rf_switch;
> > +	hw = rfss->hw_rf_switch;
> 
> Same here.

Same here.

> thanks,
> 
> greg k-h
Arnd Bergmann Feb. 18, 2021, 6:32 p.m. UTC | #3
On Thu, Feb 18, 2021 at 10:54 AM Muhammad Usama Anjum
<musamaanjum@gmail.com> wrote:
>
> On Thu, 2021-02-18 at 10:40 +0100, Greg KH wrote:
> > On Thu, Feb 18, 2021 at 02:21:54PM +0500, Muhammad Usama Anjum wrote:
> > > It is wrong to change the endianness of a variable which has just one
> > > byte size.
> > >
> > > Sparse warnings fixed:
> > > drivers/staging//wimax/i2400m/control.c:452:17: warning: cast to restricted __le32
> > > drivers/staging//wimax/i2400m/control.c:452:17: warning: cast to restricted __le32
> > > drivers/staging//wimax/i2400m/op-rfkill.c:159:14: warning: cast to restricted __le32
> > > drivers/staging//wimax/i2400m/op-rfkill.c:160:14: warning: cast to restricted __le32
> > >
> > > Signed-off-by: Muhammad Usama Anjum <musamaanjum@gmail.com>
> > > ---
> > >  drivers/staging/wimax/i2400m/control.c   | 4 ++--
> > >  drivers/staging/wimax/i2400m/op-rfkill.c | 4 ++--
> > >  2 files changed, 4 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/staging/wimax/i2400m/control.c b/drivers/staging/wimax/i2400m/control.c
> > > index 1e270b2101e8..b6b2788af162 100644
> > > --- a/drivers/staging/wimax/i2400m/control.c
> > > +++ b/drivers/staging/wimax/i2400m/control.c
> > > @@ -452,8 +452,8 @@ void i2400m_report_state_parse_tlv(struct i2400m *i2400m,
> > >             d_printf(2, dev, "%s: RF status TLV "
> > >                      "found (0x%04x), sw 0x%02x hw 0x%02x\n",
> > >                      tag, I2400M_TLV_RF_STATUS,
> > > -                    le32_to_cpu(rfss->sw_rf_switch),
> > > -                    le32_to_cpu(rfss->hw_rf_switch));
> > > +                    rfss->sw_rf_switch,
> > > +                    rfss->hw_rf_switch);
> >
> > What do you mean by "one byte"?  This is a le32 sized variable, right?
> > If not, why isn't the le32_to_cpu() call complaining?
>
> These two variables are of type _u8, one byte.
>         __u8 sw_rf_switch;
>         __u8 hw_rf_switch;
> They aren't of type __le32. le32_to_cpu() macro should have
> complained. But it isn't complaining. It seems like whatever we pass
> to this macro, it casts it to __le32 forcefully (it seems like wrong).
> So we'll never get any complain from this macro directly. But we are
> getting complain from the sparse.
>
> For big endian:
> #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
> For little endian:
> #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))

Right, it seems this driver has been broken on big-endian ever since
it was first merged in 2008.

        Arnd

Patch
diff mbox series

diff --git a/drivers/staging/wimax/i2400m/control.c b/drivers/staging/wimax/i2400m/control.c
index 1e270b2101e8..b6b2788af162 100644
--- a/drivers/staging/wimax/i2400m/control.c
+++ b/drivers/staging/wimax/i2400m/control.c
@@ -452,8 +452,8 @@  void i2400m_report_state_parse_tlv(struct i2400m *i2400m,
 		d_printf(2, dev, "%s: RF status TLV "
 			 "found (0x%04x), sw 0x%02x hw 0x%02x\n",
 			 tag, I2400M_TLV_RF_STATUS,
-			 le32_to_cpu(rfss->sw_rf_switch),
-			 le32_to_cpu(rfss->hw_rf_switch));
+			 rfss->sw_rf_switch,
+			 rfss->hw_rf_switch);
 		i2400m_report_tlv_rf_switches_status(i2400m, rfss);
 	}
 	if (0 == i2400m_tlv_match(tlv, I2400M_TLV_MEDIA_STATUS, sizeof(*ms))) {
diff --git a/drivers/staging/wimax/i2400m/op-rfkill.c b/drivers/staging/wimax/i2400m/op-rfkill.c
index fbddf2e18c14..a159808f0ec2 100644
--- a/drivers/staging/wimax/i2400m/op-rfkill.c
+++ b/drivers/staging/wimax/i2400m/op-rfkill.c
@@ -156,8 +156,8 @@  void i2400m_report_tlv_rf_switches_status(
 	enum i2400m_rf_switch_status hw, sw;
 	enum wimax_st wimax_state;
 
-	sw = le32_to_cpu(rfss->sw_rf_switch);
-	hw = le32_to_cpu(rfss->hw_rf_switch);
+	sw = rfss->sw_rf_switch;
+	hw = rfss->hw_rf_switch;
 
 	d_fnstart(3, dev, "(i2400m %p rfss %p [hw %u sw %u])\n",
 		  i2400m, rfss, hw, sw);