linux-kernel - RE: [PATCH] qed: Remove unneeded enumerated type core_tx

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Message-ID: <CY1PR07MB2554AFA55E8084990E14D55780EA0@CY1PR07MB2554.namprd07.prod.outlook.com>
Date:   Thu, 4 Oct 2018 16:23:43 +0000
From:   "Tayar, Tomer" <Tomer.Tayar@...ium.com>
To:     Nathan Chancellor <natechancellor@...il.com>,
        "Elior, Ariel" <Ariel.Elior@...ium.com>,
        Dept-Eng Everest Linux L2 <Dept-EngEverestLinuxL2@...ium.com>,
        "David S. Miller" <davem@...emloft.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: RE: [PATCH] qed: Remove unneeded enumerated type core_tx_dest

From: Nathan Chancellor <natechancellor@...il.com>
Sent: Thursday, October 04, 2018 3:09 AM
 
> Clang warns when one enumerated type is implicitly converted to another.
> 
> drivers/net/ethernet/qlogic/qed/qed_ll2.c:799:32: warning: implicit
> conversion from enumeration type 'enum core_tx_dest' to different
> enumeration type 'enum qed_ll2_tx_dest' [-Wenum-conversion]
>                 tx_pkt.tx_dest = p_ll2_conn->tx_dest;
>                                ~ ~~~~~~~~~~~~^~~~~~~
> 1 warning generated.
> 
> These enumerated types are not 1 to 1:
> 
> /* Light L2 TX Destination */
> enum core_tx_dest {
>     CORE_TX_DEST_NW,
>     CORE_TX_DEST_LB,
>     CORE_TX_DEST_RESERVED,
>     CORE_TX_DEST_DROP,
>     MAX_CORE_TX_DEST
> };
> 
> enum qed_ll2_tx_dest {
>     QED_LL2_TX_DEST_NW, /* Light L2 TX Destination to the Network */
>     QED_LL2_TX_DEST_LB, /* Light L2 TX Destination to the Loopback */
>     QED_LL2_TX_DEST_DROP, /* Light L2 Drop the TX packet */
>     QED_LL2_TX_DEST_MAX
> };
> 
> Fix this conversion warning by adding CORE_TX_DEST_DROP to
> qed_ll2_tx_dest and converting all values of core_tx_dest to
> the equivalent value in qed_ll2_tx_dest so that there is no
> conversion warning or functional change.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/125
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>

[...]

> -/* Light L2 TX Destination */
> -enum core_tx_dest {
> -       CORE_TX_DEST_NW,
> -       CORE_TX_DEST_LB,
> -       CORE_TX_DEST_RESERVED,
> -       CORE_TX_DEST_DROP,
> -       MAX_CORE_TX_DEST
> -};

[...]

>         QED_LL2_TX_DEST_NW, /* Light L2 TX Destination to the Network */
>         QED_LL2_TX_DEST_LB, /* Light L2 TX Destination to the Loopback */
>         QED_LL2_TX_DEST_DROP, /* Light L2 Drop the TX packet */
> +       QED_LL2_TX_DEST_DROP_CORE, /* CORE_TX_DEST_DROP value */
>         QED_LL2_TX_DEST_MAX
>  };

Thanks Nathan for finding this issue.
"enum core_tx_dest" is for the interface with the device FW, while "enum qed_ll2_tx_dest" is for the interface with other qed* kernel modules.
The distinction is on purpose, so "enum core_tx_dest" shouldn't be deleted.
Maybe an explicit switch/case would be better as a fix?
E.g. -
-		tx_pkt.tx_dest = p_ll2_conn->tx_dest;
+		switch (p_ll2_conn->tx_dest) {
+		case CORE_TX_DEST_NW:
+			tx_pkt.tx_dest = QED_LL2_TX_DEST_NW;
+			break;
+		case CORE_TX_DEST_LB:
+			tx_pkt.tx_dest = QED_LL2_TX_DEST_LB;
+			break;
+		case CORE_TX_DEST_DROP:
+			tx_pkt.tx_dest = QED_LL2_TX_DEST_DROP;
+			break;
+		default:
+			tx_pkt.tx_dest = QED_LL2_TX_DEST_DROP;
+		}