diff mbox

[dpdk-dev,v9,01/25] eal: define macro container_of

Message ID 1473257297-7221-2-git-send-email-shreyansh.jain@nxp.com (mailing list archive)
State Superseded, archived
Headers

Commit Message

Shreyansh Jain Sept. 7, 2016, 2:07 p.m. UTC 
  Signed-off-by: Jan Viktorin <viktorin@rehivetech.com>
Signed-off-by: Shreyansh Jain <shreyansh.jain@nxp.com>
---
 lib/librte_eal/common/include/rte_common.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

Comments

Ferruh Yigit Sept. 8, 2016, 2:16 p.m. UTC | #1 
On 9/7/2016 3:07 PM, Shreyansh Jain wrote:
> Signed-off-by: Jan Viktorin <viktorin@rehivetech.com>
> Signed-off-by: Shreyansh Jain <shreyansh.jain@nxp.com>
> ---
>  lib/librte_eal/common/include/rte_common.h | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h
> index 332f2a4..c5d94f3 100644
> --- a/lib/librte_eal/common/include/rte_common.h
> +++ b/lib/librte_eal/common/include/rte_common.h
> @@ -322,6 +322,27 @@ rte_bsf32(uint32_t v)
>  #define offsetof(TYPE, MEMBER)  __builtin_offsetof (TYPE, MEMBER)
>  #endif
>  
> +/**
> + * Return pointer to the wrapping struct instance.
> + * Example:
> + *
> + *  struct wrapper {
> + *      ...
> + *      struct child c;
> + *      ...
> + *  };
> + *
> + *  struct child *x = obtain(...);
> + *  struct wrapper *w = container_of(x, struct wrapper, c);
> + *
> + * Some implementation already have this defined, thus, conditional
> + * declaration.
> + */
> +#ifndef container_of
> +#define container_of(p, type, member) \
> +	((type *) (((char *) (p)) - offsetof(type, member)))
> +#endif
> +
>  #define _RTE_STR(x) #x
>  /** Take a macro value and get a string version of it */
>  #define RTE_STR(x) _RTE_STR(x)
> 

Some mlx5 files includes dpdk version of container_of first, they
produce following warning:

In file included from .../dpdk/build/include/rte_mbuf.h:57:0,
                 from .../dpdk/build/include/rte_ether.h:52,
                 from .../dpdk/drivers/net/mlx5/mlx5_trigger.c:38:
/usr/include/infiniband/verbs.h: In function ‘verbs_get_device’:
.../dpdk/build/include/rte_common.h:343:14: warning: cast discards
‘const’ qualifier from pointer target type [-Wcast-qual]
  ((type *) (((char *) (p)) - offsetof(type, member)))

The verbs.h version of container_of is same with dpdk one, I am not able
to find why one gives warning but other not.

Regards,
ferruh
Shreyansh Jain Sept. 9, 2016, 4:19 a.m. UTC | #2 
Hi Ferruh,

On Thursday 08 September 2016 07:46 PM, Ferruh Yigit wrote:
> On 9/7/2016 3:07 PM, Shreyansh Jain wrote:
>> Signed-off-by: Jan Viktorin <viktorin@rehivetech.com>
>> Signed-off-by: Shreyansh Jain <shreyansh.jain@nxp.com>
>> ---
>>  lib/librte_eal/common/include/rte_common.h | 21 +++++++++++++++++++++
>>  1 file changed, 21 insertions(+)
>>
>> diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h
>> index 332f2a4..c5d94f3 100644
>> --- a/lib/librte_eal/common/include/rte_common.h
>> +++ b/lib/librte_eal/common/include/rte_common.h
>> @@ -322,6 +322,27 @@ rte_bsf32(uint32_t v)
>>  #define offsetof(TYPE, MEMBER)  __builtin_offsetof (TYPE, MEMBER)
>>  #endif
>>
>> +/**
>> + * Return pointer to the wrapping struct instance.
>> + * Example:
>> + *
>> + *  struct wrapper {
>> + *      ...
>> + *      struct child c;
>> + *      ...
>> + *  };
>> + *
>> + *  struct child *x = obtain(...);
>> + *  struct wrapper *w = container_of(x, struct wrapper, c);
>> + *
>> + * Some implementation already have this defined, thus, conditional
>> + * declaration.
>> + */
>> +#ifndef container_of
>> +#define container_of(p, type, member) \
>> +	((type *) (((char *) (p)) - offsetof(type, member)))
>> +#endif
>> +
>>  #define _RTE_STR(x) #x
>>  /** Take a macro value and get a string version of it */
>>  #define RTE_STR(x) _RTE_STR(x)
>>
>
> Some mlx5 files includes dpdk version of container_of first, they
> produce following warning:
>
> In file included from .../dpdk/build/include/rte_mbuf.h:57:0,
>                  from .../dpdk/build/include/rte_ether.h:52,
>                  from .../dpdk/drivers/net/mlx5/mlx5_trigger.c:38:
> /usr/include/infiniband/verbs.h: In function ‘verbs_get_device’:
> ..../dpdk/build/include/rte_common.h:343:14: warning: cast discards
> ‘const’ qualifier from pointer target type [-Wcast-qual]
>   ((type *) (((char *) (p)) - offsetof(type, member)))
>
> The verbs.h version of container_of is same with dpdk one, I am not able
> to find why one gives warning but other not.

Thanks for highlighting. I am setting up my environment and will have a 
look.

>
> Regards,
> ferruh
>
>
Adrien Mazarguil Sept. 9, 2016, 8:55 a.m. UTC | #3 
On Fri, Sep 09, 2016 at 09:49:06AM +0530, Shreyansh Jain wrote:
> Hi Ferruh,
> 
> On Thursday 08 September 2016 07:46 PM, Ferruh Yigit wrote:
> >On 9/7/2016 3:07 PM, Shreyansh Jain wrote:
> >>Signed-off-by: Jan Viktorin <viktorin@rehivetech.com>
> >>Signed-off-by: Shreyansh Jain <shreyansh.jain@nxp.com>
> >>---
> >> lib/librte_eal/common/include/rte_common.h | 21 +++++++++++++++++++++
> >> 1 file changed, 21 insertions(+)
> >>
> >>diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h
> >>index 332f2a4..c5d94f3 100644
> >>--- a/lib/librte_eal/common/include/rte_common.h
> >>+++ b/lib/librte_eal/common/include/rte_common.h
> >>@@ -322,6 +322,27 @@ rte_bsf32(uint32_t v)
> >> #define offsetof(TYPE, MEMBER)  __builtin_offsetof (TYPE, MEMBER)
> >> #endif
> >>
> >>+/**
> >>+ * Return pointer to the wrapping struct instance.
> >>+ * Example:
> >>+ *
> >>+ *  struct wrapper {
> >>+ *      ...
> >>+ *      struct child c;
> >>+ *      ...
> >>+ *  };
> >>+ *
> >>+ *  struct child *x = obtain(...);
> >>+ *  struct wrapper *w = container_of(x, struct wrapper, c);
> >>+ *
> >>+ * Some implementation already have this defined, thus, conditional
> >>+ * declaration.
> >>+ */
> >>+#ifndef container_of
> >>+#define container_of(p, type, member) \
> >>+	((type *) (((char *) (p)) - offsetof(type, member)))
> >>+#endif
> >>+
> >> #define _RTE_STR(x) #x
> >> /** Take a macro value and get a string version of it */
> >> #define RTE_STR(x) _RTE_STR(x)
> >>
> >
> >Some mlx5 files includes dpdk version of container_of first, they
> >produce following warning:
> >
> >In file included from .../dpdk/build/include/rte_mbuf.h:57:0,
> >                 from .../dpdk/build/include/rte_ether.h:52,
> >                 from .../dpdk/drivers/net/mlx5/mlx5_trigger.c:38:
> >/usr/include/infiniband/verbs.h: In function ‘verbs_get_device’:
> >..../dpdk/build/include/rte_common.h:343:14: warning: cast discards
> >‘const’ qualifier from pointer target type [-Wcast-qual]
> >  ((type *) (((char *) (p)) - offsetof(type, member)))
> >
> >The verbs.h version of container_of is same with dpdk one, I am not able
> >to find why one gives warning but other not.
> 
> Thanks for highlighting. I am setting up my environment and will have a
> look.

This warning is a known issue in the Verbs header that will be addressed
eventually. It occurs even without Shreyansh's patch (more likely when
CONFIG_RTE_LIBRTE_MLX4_DEBUG and/or CONFIG_RTE_LIBRTE_MLX5_DEBUG are
enabled).

Your container_of() macro is fine, no need to spend time on this.
Shreyansh Jain Sept. 9, 2016, 10:44 a.m. UTC | #4 
Hi Adrien,

On Friday 09 September 2016 02:25 PM, Adrien Mazarguil wrote:
> This warning is a known issue in the Verbs header that will be addressed
> eventually. It occurs even without Shreyansh's patch (more likely when
> CONFIG_RTE_LIBRTE_MLX4_DEBUG and/or CONFIG_RTE_LIBRTE_MLX5_DEBUG are
> enabled).
>
> Your container_of() macro is fine, no need to spend time on this.
>
> --

Thank you very much for clarifying this.
diff mbox

Patch

diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h
index 332f2a4..c5d94f3 100644
--- a/lib/librte_eal/common/include/rte_common.h
+++ b/lib/librte_eal/common/include/rte_common.h
@@ -322,6 +322,27 @@  rte_bsf32(uint32_t v)
 #define offsetof(TYPE, MEMBER)  __builtin_offsetof (TYPE, MEMBER)
 #endif
 
+/**
+ * Return pointer to the wrapping struct instance.
+ * Example:
+ *
+ *  struct wrapper {
+ *      ...
+ *      struct child c;
+ *      ...
+ *  };
+ *
+ *  struct child *x = obtain(...);
+ *  struct wrapper *w = container_of(x, struct wrapper, c);
+ *
+ * Some implementation already have this defined, thus, conditional
+ * declaration.
+ */
+#ifndef container_of
+#define container_of(p, type, member) \
+	((type *) (((char *) (p)) - offsetof(type, member)))
+#endif
+
 #define _RTE_STR(x) #x
 /** Take a macro value and get a string version of it */
 #define RTE_STR(x) _RTE_STR(x)