* [PATCH] net: stmmac: xgmac: add missing parentheses to fix precendence error
@ 2019-10-02 11:08 Colin King
2019-10-02 13:33 ` Dan Carpenter
0 siblings, 1 reply; 6+ messages in thread
From: Colin King @ 2019-10-02 11:08 UTC (permalink / raw)
To: Giuseppe Cavallaro, Alexandre Torgue, Jose Abreu,
David S . Miller, Maxime Coquelin, netdev, linux-stm32,
linux-arm-kernel
Cc: kernel-janitors, linux-kernel
From: Colin Ian King <colin.king@canonical.com>
The expression !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10 is always zero, so
the masking operation is incorrect. Fix this by adding the missing
parentheses to correctly bind the negate operator on the entire expression.
Addresses-Coverity: ("Operands don't affect result")
Fixes: c2b69474d63b ("net: stmmac: xgmac: Correct RAVSEL field interpretation")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
index 965cbe3e6f51..2e814aa64a5c 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
@@ -369,7 +369,7 @@ static void dwxgmac2_get_hw_feature(void __iomem *ioaddr,
dma_cap->eee = (hw_cap & XGMAC_HWFEAT_EEESEL) >> 13;
dma_cap->atime_stamp = (hw_cap & XGMAC_HWFEAT_TSSEL) >> 12;
dma_cap->av = (hw_cap & XGMAC_HWFEAT_AVSEL) >> 11;
- dma_cap->av &= !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10;
+ dma_cap->av &= !((hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10);
dma_cap->arpoffsel = (hw_cap & XGMAC_HWFEAT_ARPOFFSEL) >> 9;
dma_cap->rmon = (hw_cap & XGMAC_HWFEAT_MMCSEL) >> 8;
dma_cap->pmt_magic_frame = (hw_cap & XGMAC_HWFEAT_MGKSEL) >> 7;
--
2.20.1
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^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] net: stmmac: xgmac: add missing parentheses to fix precendence error
2019-10-02 11:08 [PATCH] net: stmmac: xgmac: add missing parentheses to fix precendence error Colin King
@ 2019-10-02 13:33 ` Dan Carpenter
2019-10-02 13:40 ` Colin Ian King
2019-10-02 13:42 ` Dan Carpenter
0 siblings, 2 replies; 6+ messages in thread
From: Dan Carpenter @ 2019-10-02 13:33 UTC (permalink / raw)
To: Colin King
Cc: Alexandre Torgue, netdev, kernel-janitors, linux-kernel,
linux-stm32, Jose Abreu, Maxime Coquelin, Giuseppe Cavallaro,
David S . Miller, linux-arm-kernel
On Wed, Oct 02, 2019 at 12:08:49PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> The expression !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10 is always zero, so
> the masking operation is incorrect. Fix this by adding the missing
> parentheses to correctly bind the negate operator on the entire expression.
>
> Addresses-Coverity: ("Operands don't affect result")
> Fixes: c2b69474d63b ("net: stmmac: xgmac: Correct RAVSEL field interpretation")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
> drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> index 965cbe3e6f51..2e814aa64a5c 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> @@ -369,7 +369,7 @@ static void dwxgmac2_get_hw_feature(void __iomem *ioaddr,
> dma_cap->eee = (hw_cap & XGMAC_HWFEAT_EEESEL) >> 13;
> dma_cap->atime_stamp = (hw_cap & XGMAC_HWFEAT_TSSEL) >> 12;
> dma_cap->av = (hw_cap & XGMAC_HWFEAT_AVSEL) >> 11;
> - dma_cap->av &= !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10;
> + dma_cap->av &= !((hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10);
There is no point to the shift at all.
regards,
dan carpenter
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] net: stmmac: xgmac: add missing parentheses to fix precendence error
2019-10-02 13:33 ` Dan Carpenter
@ 2019-10-02 13:40 ` Colin Ian King
2019-10-02 13:42 ` Dan Carpenter
1 sibling, 0 replies; 6+ messages in thread
From: Colin Ian King @ 2019-10-02 13:40 UTC (permalink / raw)
To: Dan Carpenter
Cc: Alexandre Torgue, netdev, kernel-janitors, linux-kernel,
linux-stm32, Jose Abreu, Maxime Coquelin, Giuseppe Cavallaro,
David S . Miller, linux-arm-kernel
On 02/10/2019 14:33, Dan Carpenter wrote:
> On Wed, Oct 02, 2019 at 12:08:49PM +0100, Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> The expression !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10 is always zero, so
>> the masking operation is incorrect. Fix this by adding the missing
>> parentheses to correctly bind the negate operator on the entire expression.
>>
>> Addresses-Coverity: ("Operands don't affect result")
>> Fixes: c2b69474d63b ("net: stmmac: xgmac: Correct RAVSEL field interpretation")
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>> ---
>> drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
>> index 965cbe3e6f51..2e814aa64a5c 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
>> @@ -369,7 +369,7 @@ static void dwxgmac2_get_hw_feature(void __iomem *ioaddr,
>> dma_cap->eee = (hw_cap & XGMAC_HWFEAT_EEESEL) >> 13;
>> dma_cap->atime_stamp = (hw_cap & XGMAC_HWFEAT_TSSEL) >> 12;
>> dma_cap->av = (hw_cap & XGMAC_HWFEAT_AVSEL) >> 11;
>> - dma_cap->av &= !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10;
>> + dma_cap->av &= !((hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10);
>
> There is no point to the shift at all.
I must admit I was so focused on figuring out the original intent of the
code I totally missed that optimization step. I'll send a V2.
>
> regards,
> dan carpenter
>
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] net: stmmac: xgmac: add missing parentheses to fix precendence error
2019-10-02 13:33 ` Dan Carpenter
2019-10-02 13:40 ` Colin Ian King
@ 2019-10-02 13:42 ` Dan Carpenter
2019-10-02 13:53 ` Colin Ian King
1 sibling, 1 reply; 6+ messages in thread
From: Dan Carpenter @ 2019-10-02 13:42 UTC (permalink / raw)
To: Colin King
Cc: Alexandre Torgue, netdev, kernel-janitors, linux-kernel,
linux-stm32, Jose Abreu, Maxime Coquelin, Giuseppe Cavallaro,
David S . Miller, linux-arm-kernel
On Wed, Oct 02, 2019 at 04:33:57PM +0300, Dan Carpenter wrote:
> On Wed, Oct 02, 2019 at 12:08:49PM +0100, Colin King wrote:
> > From: Colin Ian King <colin.king@canonical.com>
> >
> > The expression !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10 is always zero, so
> > the masking operation is incorrect. Fix this by adding the missing
> > parentheses to correctly bind the negate operator on the entire expression.
> >
> > Addresses-Coverity: ("Operands don't affect result")
> > Fixes: c2b69474d63b ("net: stmmac: xgmac: Correct RAVSEL field interpretation")
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > ---
> > drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> > index 965cbe3e6f51..2e814aa64a5c 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> > @@ -369,7 +369,7 @@ static void dwxgmac2_get_hw_feature(void __iomem *ioaddr,
> > dma_cap->eee = (hw_cap & XGMAC_HWFEAT_EEESEL) >> 13;
> > dma_cap->atime_stamp = (hw_cap & XGMAC_HWFEAT_TSSEL) >> 12;
> > dma_cap->av = (hw_cap & XGMAC_HWFEAT_AVSEL) >> 11;
> > - dma_cap->av &= !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10;
> > + dma_cap->av &= !((hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10);
>
> There is no point to the shift at all.
Sorry I meant to say it should be a bitwise NOT, right? I was just
looking at some other dma_cap stuff that did this same thing... I can't
find it now...
regards,
dan carpenter
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linux-arm-kernel@lists.infradead.org
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] net: stmmac: xgmac: add missing parentheses to fix precendence error
2019-10-02 13:42 ` Dan Carpenter
@ 2019-10-02 13:53 ` Colin Ian King
2019-10-02 14:07 ` Dan Carpenter
0 siblings, 1 reply; 6+ messages in thread
From: Colin Ian King @ 2019-10-02 13:53 UTC (permalink / raw)
To: Dan Carpenter
Cc: Alexandre Torgue, netdev, kernel-janitors, linux-kernel,
linux-stm32, Jose Abreu, Maxime Coquelin, Giuseppe Cavallaro,
David S . Miller, linux-arm-kernel
On 02/10/2019 14:42, Dan Carpenter wrote:
> On Wed, Oct 02, 2019 at 04:33:57PM +0300, Dan Carpenter wrote:
>> On Wed, Oct 02, 2019 at 12:08:49PM +0100, Colin King wrote:
>>> From: Colin Ian King <colin.king@canonical.com>
>>>
>>> The expression !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10 is always zero, so
>>> the masking operation is incorrect. Fix this by adding the missing
>>> parentheses to correctly bind the negate operator on the entire expression.
>>>
>>> Addresses-Coverity: ("Operands don't affect result")
>>> Fixes: c2b69474d63b ("net: stmmac: xgmac: Correct RAVSEL field interpretation")
>>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>>> ---
>>> drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
>>> index 965cbe3e6f51..2e814aa64a5c 100644
>>> --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
>>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
>>> @@ -369,7 +369,7 @@ static void dwxgmac2_get_hw_feature(void __iomem *ioaddr,
>>> dma_cap->eee = (hw_cap & XGMAC_HWFEAT_EEESEL) >> 13;
>>> dma_cap->atime_stamp = (hw_cap & XGMAC_HWFEAT_TSSEL) >> 12;
>>> dma_cap->av = (hw_cap & XGMAC_HWFEAT_AVSEL) >> 11;
>>> - dma_cap->av &= !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10;
>>> + dma_cap->av &= !((hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10);
>>
>> There is no point to the shift at all.
>
> Sorry I meant to say it should be a bitwise NOT, right? I was just
> looking at some other dma_cap stuff that did this same thing... I can't
> find it now...
In drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c it is being used like
a boolean and not a bitmask'd value:
if (!priv->dma_cap.av)
so the original logic is to do boolean flag merging rather than bit-wise
logic.
>
> regards,
> dan carpenter
>
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] net: stmmac: xgmac: add missing parentheses to fix precendence error
2019-10-02 13:53 ` Colin Ian King
@ 2019-10-02 14:07 ` Dan Carpenter
0 siblings, 0 replies; 6+ messages in thread
From: Dan Carpenter @ 2019-10-02 14:07 UTC (permalink / raw)
To: Colin Ian King
Cc: Alexandre Torgue, netdev, kernel-janitors, linux-kernel,
linux-stm32, Jose Abreu, Maxime Coquelin, Giuseppe Cavallaro,
David S . Miller, linux-arm-kernel
On Wed, Oct 02, 2019 at 02:53:17PM +0100, Colin Ian King wrote:
> On 02/10/2019 14:42, Dan Carpenter wrote:
> > On Wed, Oct 02, 2019 at 04:33:57PM +0300, Dan Carpenter wrote:
> >> On Wed, Oct 02, 2019 at 12:08:49PM +0100, Colin King wrote:
> >>> From: Colin Ian King <colin.king@canonical.com>
> >>>
> >>> The expression !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10 is always zero, so
> >>> the masking operation is incorrect. Fix this by adding the missing
> >>> parentheses to correctly bind the negate operator on the entire expression.
> >>>
> >>> Addresses-Coverity: ("Operands don't affect result")
> >>> Fixes: c2b69474d63b ("net: stmmac: xgmac: Correct RAVSEL field interpretation")
> >>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> >>> ---
> >>> drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c | 2 +-
> >>> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> >>> index 965cbe3e6f51..2e814aa64a5c 100644
> >>> --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> >>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> >>> @@ -369,7 +369,7 @@ static void dwxgmac2_get_hw_feature(void __iomem *ioaddr,
> >>> dma_cap->eee = (hw_cap & XGMAC_HWFEAT_EEESEL) >> 13;
> >>> dma_cap->atime_stamp = (hw_cap & XGMAC_HWFEAT_TSSEL) >> 12;
> >>> dma_cap->av = (hw_cap & XGMAC_HWFEAT_AVSEL) >> 11;
> >>> - dma_cap->av &= !(hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10;
> >>> + dma_cap->av &= !((hw_cap & XGMAC_HWFEAT_RAVSEL) >> 10);
> >>
> >> There is no point to the shift at all.
> >
> > Sorry I meant to say it should be a bitwise NOT, right? I was just
> > looking at some other dma_cap stuff that did this same thing... I can't
> > find it now...
>
> In drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c it is being used like
> a boolean and not a bitmask'd value:
>
> if (!priv->dma_cap.av)
>
> so the original logic is to do boolean flag merging rather than bit-wise
> logic.
Oh yeah. Thanks. This code is hard to read.
It would be better to just write it like this:
if (hw_cap & XGMAC_HWFEAT_AVSEL) && !(hw_cap & XGMAC_HWFEAT_RAVSEL)
dma_cap->av = true;
else
dma_cap->av = false;
All these very shifts are concise but they introduce bugs like this one
you have found.
regards,
dan carpenter
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^ permalink raw reply [flat|nested] 6+ messages in thread
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-- links below jump to the message on this page --
2019-10-02 11:08 [PATCH] net: stmmac: xgmac: add missing parentheses to fix precendence error Colin King
2019-10-02 13:33 ` Dan Carpenter
2019-10-02 13:40 ` Colin Ian King
2019-10-02 13:42 ` Dan Carpenter
2019-10-02 13:53 ` Colin Ian King
2019-10-02 14:07 ` Dan Carpenter
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