diff mbox series

[v3,2/5] net/sfc: fix non-constant expression in RTE_BUILD_BUG_ON()

Message ID 20240116184307.162882-3-stephen@networkplumber.org (mailing list archive)
State Superseded, archived
Delegated to: Thomas Monjalon
Headers
Series use static_assert to catch build errors |

Checks

Context Check Description
ci/checkpatch warning coding style issues

Commit Message

Stephen Hemminger Jan. 16, 2024, 6:41 p.m. UTC 
  The macro RTE_MIN has some hidden assignments to provide type
safety which means the statement can not be fully evaluated in
first pass of compiler. Replace RTE_MIN() with equivalent macro.

This will cause errors from checkpatch about multiple evaluations
of same expression in macro but it is ok in this case.

Fixes: 4f936666d790 ("net/sfc: support TSO for EF100 native datapath")
Cc: ivan.malov@oktetlabs.ru
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
---
 drivers/net/sfc/sfc_ef100_tx.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

Comments

Andrew Rybchenko Jan. 17, 2024, 7:57 a.m. UTC | #1 
On 1/16/24 21:41, Stephen Hemminger wrote:
> The macro RTE_MIN has some hidden assignments to provide type
> safety which means the statement can not be fully evaluated in
> first pass of compiler. Replace RTE_MIN() with equivalent macro.
> 
> This will cause errors from checkpatch about multiple evaluations
> of same expression in macro but it is ok in this case.
> 
> Fixes: 4f936666d790 ("net/sfc: support TSO for EF100 native datapath")

I'm not sure that it is really a fix.

> Cc: ivan.malov@oktetlabs.ru
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
> ---
>   drivers/net/sfc/sfc_ef100_tx.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/sfc/sfc_ef100_tx.c b/drivers/net/sfc/sfc_ef100_tx.c
> index 1b6374775f07..f4bcadc1e8e0 100644
> --- a/drivers/net/sfc/sfc_ef100_tx.c
> +++ b/drivers/net/sfc/sfc_ef100_tx.c
> @@ -26,6 +26,10 @@
>   #include "sfc_ef100.h"
>   #include "sfc_nic_dma_dp.h"
>   
> +#ifndef MIN
> +/* not typesafe but is a constant */
> +#define MIN(x, y) ((x) < (y) ? (x) : (y))
> +#endif

IMHO adding it in specific driver is a wrong direction. I'm afraid it
will result in duplication of such macros in code base without clear
reason why.

May be it is better to add it with a proper name to EAL?

>   
>   #define sfc_ef100_tx_err(_txq, ...) \
>   	SFC_DP_LOG(SFC_KVARG_DATAPATH_EF100, ERR, &(_txq)->dp.dpq, __VA_ARGS__)
> @@ -563,8 +567,7 @@ sfc_ef100_tx_pkt_descs_max(const struct rte_mbuf *m)
>   		 * (split into many Tx descriptors).
>   		 */
>   		RTE_BUILD_BUG_ON(SFC_EF100_TX_SEND_DESC_LEN_MAX <
> -				 RTE_MIN((unsigned int)EFX_MAC_PDU_MAX,
> -				 SFC_MBUF_SEG_LEN_MAX));
> +				 MIN((unsigned int)EFX_MAC_PDU_MAX, SFC_MBUF_SEG_LEN_MAX));
>   	}
>   
>   	if (m->ol_flags & sfc_dp_mport_override) {
diff mbox series

Patch

diff --git a/drivers/net/sfc/sfc_ef100_tx.c b/drivers/net/sfc/sfc_ef100_tx.c
index 1b6374775f07..f4bcadc1e8e0 100644
--- a/drivers/net/sfc/sfc_ef100_tx.c
+++ b/drivers/net/sfc/sfc_ef100_tx.c
@@ -26,6 +26,10 @@ 
 #include "sfc_ef100.h"
 #include "sfc_nic_dma_dp.h"
 
+#ifndef MIN
+/* not typesafe but is a constant */
+#define MIN(x, y) ((x) < (y) ? (x) : (y))
+#endif
 
 #define sfc_ef100_tx_err(_txq, ...) \
 	SFC_DP_LOG(SFC_KVARG_DATAPATH_EF100, ERR, &(_txq)->dp.dpq, __VA_ARGS__)
@@ -563,8 +567,7 @@  sfc_ef100_tx_pkt_descs_max(const struct rte_mbuf *m)
 		 * (split into many Tx descriptors).
 		 */
 		RTE_BUILD_BUG_ON(SFC_EF100_TX_SEND_DESC_LEN_MAX <
-				 RTE_MIN((unsigned int)EFX_MAC_PDU_MAX,
-				 SFC_MBUF_SEG_LEN_MAX));
+				 MIN((unsigned int)EFX_MAC_PDU_MAX, SFC_MBUF_SEG_LEN_MAX));
 	}
 
 	if (m->ol_flags & sfc_dp_mport_override) {