2023-02-14 13:20:15

by Arnd Bergmann

[permalink] [raw]
Subject: [PATCH] ethernet: ice: avoid gcc-9 integer overflow warning

From: Arnd Bergmann <[email protected]>

With older compilers like gcc-9, the calculation of the vlan
priority field causes a warning from the byteswap:

In file included from drivers/net/ethernet/intel/ice/ice_tc_lib.c:4:
drivers/net/ethernet/intel/ice/ice_tc_lib.c: In function 'ice_parse_cls_flower':
include/uapi/linux/swab.h:15:15: error: integer overflow in expression '(int)(short unsigned int)((int)match.key-><U67c8>.<U6698>.vlan_priority << 13) & 57344 & 255' of type 'int' results in '0' [-Werror=overflow]
15 | (((__u16)(x) & (__u16)0x00ffU) << 8) | \
| ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
include/uapi/linux/swab.h:106:2: note: in expansion of macro '___constant_swab16'
106 | ___constant_swab16(x) : \
| ^~~~~~~~~~~~~~~~~~
include/uapi/linux/byteorder/little_endian.h:42:43: note: in expansion of macro '__swab16'
42 | #define __cpu_to_be16(x) ((__force __be16)__swab16((x)))
| ^~~~~~~~
include/linux/byteorder/generic.h:96:21: note: in expansion of macro '__cpu_to_be16'
96 | #define cpu_to_be16 __cpu_to_be16
| ^~~~~~~~~~~~~
drivers/net/ethernet/intel/ice/ice_tc_lib.c:1458:5: note: in expansion of macro 'cpu_to_be16'
1458 | cpu_to_be16((match.key->vlan_priority <<
| ^~~~~~~~~~~

The code looks correct to me, so just avoid the warning by replacing
the macro expansion with an intermediate variable.

Fixes: 34800178b302 ("ice: Add support for VLAN priority filters in switchdev")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/net/ethernet/intel/ice/ice_tc_lib.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_tc_lib.c b/drivers/net/ethernet/intel/ice/ice_tc_lib.c
index 6b48cbc049c6..e9932446185c 100644
--- a/drivers/net/ethernet/intel/ice/ice_tc_lib.c
+++ b/drivers/net/ethernet/intel/ice/ice_tc_lib.c
@@ -1453,10 +1453,9 @@ ice_parse_cls_flower(struct net_device *filter_dev, struct ice_vsi *vsi,
}

if (match.mask->vlan_priority) {
+ u16 prio = (match.key->vlan_priority << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;
fltr->flags |= ICE_TC_FLWR_FIELD_VLAN_PRIO;
- headers->vlan_hdr.vlan_prio =
- cpu_to_be16((match.key->vlan_priority <<
- VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK);
+ headers->vlan_hdr.vlan_prio = cpu_to_be16(prio);
}

if (match.mask->vlan_tpid)
@@ -1487,10 +1486,9 @@ ice_parse_cls_flower(struct net_device *filter_dev, struct ice_vsi *vsi,
}

if (match.mask->vlan_priority) {
+ u16 prio = (match.key->vlan_priority << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;
fltr->flags |= ICE_TC_FLWR_FIELD_CVLAN_PRIO;
- headers->cvlan_hdr.vlan_prio =
- cpu_to_be16((match.key->vlan_priority <<
- VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK);
+ headers->cvlan_hdr.vlan_prio = cpu_to_be16(prio);
}
}

--
2.39.1



2023-02-14 14:20:59

by Alexander Lobakin

[permalink] [raw]
Subject: Re: [Intel-wired-lan] [PATCH] ethernet: ice: avoid gcc-9 integer overflow warning

From: Arnd Bergmann <[email protected]>
Date: Tue, 14 Feb 2023 14:19:49 +0100

> From: Arnd Bergmann <[email protected]>
>
> With older compilers like gcc-9, the calculation of the vlan
> priority field causes a warning from the byteswap:
>
> In file included from drivers/net/ethernet/intel/ice/ice_tc_lib.c:4:
> drivers/net/ethernet/intel/ice/ice_tc_lib.c: In function 'ice_parse_cls_flower':
> include/uapi/linux/swab.h:15:15: error: integer overflow in expression '(int)(short unsigned int)((int)match.key-><U67c8>.<U6698>.vlan_priority << 13) & 57344 & 255' of type 'int' results in '0' [-Werror=overflow]
> 15 | (((__u16)(x) & (__u16)0x00ffU) << 8) | \
> | ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
> include/uapi/linux/swab.h:106:2: note: in expansion of macro '___constant_swab16'
> 106 | ___constant_swab16(x) : \
> | ^~~~~~~~~~~~~~~~~~
> include/uapi/linux/byteorder/little_endian.h:42:43: note: in expansion of macro '__swab16'
> 42 | #define __cpu_to_be16(x) ((__force __be16)__swab16((x)))
> | ^~~~~~~~
> include/linux/byteorder/generic.h:96:21: note: in expansion of macro '__cpu_to_be16'
> 96 | #define cpu_to_be16 __cpu_to_be16
> | ^~~~~~~~~~~~~
> drivers/net/ethernet/intel/ice/ice_tc_lib.c:1458:5: note: in expansion of macro 'cpu_to_be16'
> 1458 | cpu_to_be16((match.key->vlan_priority <<
> | ^~~~~~~~~~~
>
> The code looks correct to me, so just avoid the warning by replacing
> the macro expansion with an intermediate variable.
>
> Fixes: 34800178b302 ("ice: Add support for VLAN priority filters in switchdev")

Should it have "Fixes:" tag if the code itself is correct?

> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> drivers/net/ethernet/intel/ice/ice_tc_lib.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ice/ice_tc_lib.c b/drivers/net/ethernet/intel/ice/ice_tc_lib.c
> index 6b48cbc049c6..e9932446185c 100644
> --- a/drivers/net/ethernet/intel/ice/ice_tc_lib.c
> +++ b/drivers/net/ethernet/intel/ice/ice_tc_lib.c
> @@ -1453,10 +1453,9 @@ ice_parse_cls_flower(struct net_device *filter_dev, struct ice_vsi *vsi,
> }
>
> if (match.mask->vlan_priority) {
> + u16 prio = (match.key->vlan_priority << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;

Maybe just u32?

Also, I'd go for FIELD_PREP() here. Even be16_encode_bits(). Or does it
have the same problem on GCC 9?

__be16 pri;

pri = be16_encode_bits(match.key->vlan_priority,
VLAN_PRIO_MASK);
headers->vlan_hdr.vlan_prio = pri;

But I suspect you (or somebody else) will say "please don't mix fixes
and improvements" :D Altho I'd go for this one if it silences the warning.

> fltr->flags |= ICE_TC_FLWR_FIELD_VLAN_PRIO;
> - headers->vlan_hdr.vlan_prio =
> - cpu_to_be16((match.key->vlan_priority <<
> - VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK);
> + headers->vlan_hdr.vlan_prio = cpu_to_be16(prio);
> }
>
> if (match.mask->vlan_tpid)
> @@ -1487,10 +1486,9 @@ ice_parse_cls_flower(struct net_device *filter_dev, struct ice_vsi *vsi,
> }
>
> if (match.mask->vlan_priority) {
> + u16 prio = (match.key->vlan_priority << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;
> fltr->flags |= ICE_TC_FLWR_FIELD_CVLAN_PRIO;
> - headers->cvlan_hdr.vlan_prio =
> - cpu_to_be16((match.key->vlan_priority <<
> - VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK);
> + headers->cvlan_hdr.vlan_prio = cpu_to_be16(prio);

^

> }
> }
>

Thanks,
Olek


2023-02-14 15:40:54

by Maciej Fijalkowski

[permalink] [raw]
Subject: Re: [PATCH] ethernet: ice: avoid gcc-9 integer overflow warning

On Tue, Feb 14, 2023 at 02:19:49PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> With older compilers like gcc-9, the calculation of the vlan
> priority field causes a warning from the byteswap:
>
> In file included from drivers/net/ethernet/intel/ice/ice_tc_lib.c:4:
> drivers/net/ethernet/intel/ice/ice_tc_lib.c: In function 'ice_parse_cls_flower':
> include/uapi/linux/swab.h:15:15: error: integer overflow in expression '(int)(short unsigned int)((int)match.key-><U67c8>.<U6698>.vlan_priority << 13) & 57344 & 255' of type 'int' results in '0' [-Werror=overflow]
> 15 | (((__u16)(x) & (__u16)0x00ffU) << 8) | \
> | ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
> include/uapi/linux/swab.h:106:2: note: in expansion of macro '___constant_swab16'
> 106 | ___constant_swab16(x) : \
> | ^~~~~~~~~~~~~~~~~~
> include/uapi/linux/byteorder/little_endian.h:42:43: note: in expansion of macro '__swab16'
> 42 | #define __cpu_to_be16(x) ((__force __be16)__swab16((x)))
> | ^~~~~~~~
> include/linux/byteorder/generic.h:96:21: note: in expansion of macro '__cpu_to_be16'
> 96 | #define cpu_to_be16 __cpu_to_be16
> | ^~~~~~~~~~~~~
> drivers/net/ethernet/intel/ice/ice_tc_lib.c:1458:5: note: in expansion of macro 'cpu_to_be16'
> 1458 | cpu_to_be16((match.key->vlan_priority <<
> | ^~~~~~~~~~~
>
> The code looks correct to me, so just avoid the warning by replacing
> the macro expansion with an intermediate variable.
>
> Fixes: 34800178b302 ("ice: Add support for VLAN priority filters in switchdev")
> Signed-off-by: Arnd Bergmann <[email protected]>

Reviewed-by: Maciej Fijalkowski <[email protected]>

> ---
> drivers/net/ethernet/intel/ice/ice_tc_lib.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ice/ice_tc_lib.c b/drivers/net/ethernet/intel/ice/ice_tc_lib.c
> index 6b48cbc049c6..e9932446185c 100644
> --- a/drivers/net/ethernet/intel/ice/ice_tc_lib.c
> +++ b/drivers/net/ethernet/intel/ice/ice_tc_lib.c
> @@ -1453,10 +1453,9 @@ ice_parse_cls_flower(struct net_device *filter_dev, struct ice_vsi *vsi,
> }
>
> if (match.mask->vlan_priority) {
> + u16 prio = (match.key->vlan_priority << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;

nit: usually for such scoped stack var we follow the declaration with an
empty line

> fltr->flags |= ICE_TC_FLWR_FIELD_VLAN_PRIO;
> - headers->vlan_hdr.vlan_prio =
> - cpu_to_be16((match.key->vlan_priority <<
> - VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK);
> + headers->vlan_hdr.vlan_prio = cpu_to_be16(prio);
> }
>
> if (match.mask->vlan_tpid)
> @@ -1487,10 +1486,9 @@ ice_parse_cls_flower(struct net_device *filter_dev, struct ice_vsi *vsi,
> }
>
> if (match.mask->vlan_priority) {
> + u16 prio = (match.key->vlan_priority << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;
> fltr->flags |= ICE_TC_FLWR_FIELD_CVLAN_PRIO;
> - headers->cvlan_hdr.vlan_prio =
> - cpu_to_be16((match.key->vlan_priority <<
> - VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK);
> + headers->cvlan_hdr.vlan_prio = cpu_to_be16(prio);
> }
> }
>
> --
> 2.39.1
>

2023-02-15 10:59:07

by David Laight

[permalink] [raw]
Subject: RE: [PATCH] ethernet: ice: avoid gcc-9 integer overflow warning

From: Arnd Bergmann
> Sent: 14 February 2023 13:20
>
> From: Arnd Bergmann <[email protected]>
>
> With older compilers like gcc-9, the calculation of the vlan
> priority field causes a warning from the byteswap:
>
...
>
> Fixes: 34800178b302 ("ice: Add support for VLAN priority filters in switchdev")
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> drivers/net/ethernet/intel/ice/ice_tc_lib.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ice/ice_tc_lib.c b/drivers/net/ethernet/intel/ice/ice_tc_lib.c
> index 6b48cbc049c6..e9932446185c 100644
> --- a/drivers/net/ethernet/intel/ice/ice_tc_lib.c
> +++ b/drivers/net/ethernet/intel/ice/ice_tc_lib.c
> @@ -1453,10 +1453,9 @@ ice_parse_cls_flower(struct net_device *filter_dev, struct ice_vsi *vsi,
> }
>
> if (match.mask->vlan_priority) {
> + u16 prio = (match.key->vlan_priority << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;
> fltr->flags |= ICE_TC_FLWR_FIELD_VLAN_PRIO;
> - headers->vlan_hdr.vlan_prio =
> - cpu_to_be16((match.key->vlan_priority <<
> - VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK);
> + headers->vlan_hdr.vlan_prio = cpu_to_be16(prio);
> }

Is there something that will do:
unsigned int pri = match.key->vlan_priority & (VLAN_PRIO_MASK >> VLAN_PRIO_SHIFT);
headers->vlan_hdr.vlan_prio = pri << (VLAN_PRIO_SHIFT ^ (le ? 8 : 0));

David

-
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