[PATCH net] net: stmmac: xgmac: use #define for string constants

[PATCH net] net: stmmac: xgmac: use #define for string constants

[Simon Horman]

The cited commit introduces and uses the string constants dpp_tx_err and
dpp_rx_err. These are assigned to constant fields of the array
dwxgmac3_error_desc.

It has been reported that on GCC 6 and 7.5.0 this results in warnings
such as:

  .../dwxgmac2_core.c:836:20: error: initialiser element is not constant
   { true, "TDPES0", dpp_tx_err },

I have been able to reproduce this using: GCC 7.5.0, 8.4.0, 9.4.0 and 10.5.0.
But not GCC 13.2.0.

So it seems this effects older compilers but not newer ones.
As Jon points out in his report, the minimum compiler supported by
the kernel is GCC 5.1, so it does seem that this ought to be fixed.

It is not clear to me what combination of 'const', if any, would address
this problem.  So this patch takes of using #defines for the string
constants

Compile tested only.

Fixes: 46eba193d04f ("net: stmmac: xgmac: fix handling of DPP safety error for DMA channels")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Closes: https://lore.kernel.org/netdev/c25eb595-8d91-40ea-9f52-efa15ebafdbc@nvidia.com/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202402081135.lAxxBXHk-lkp@intel.com/
Signed-off-by: Simon Horman <horms@kernel.org>
---
 .../net/ethernet/stmicro/stmmac/dwxgmac2_core.c    | 69 +++++++++++-----------
 1 file changed, 35 insertions(+), 34 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
index 323c57f03c93..1af2f89a0504 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
@@ -830,41 +830,42 @@ static const struct dwxgmac3_error_desc dwxgmac3_dma_errors[32]= {
 	{ false, "UNKNOWN", "Unknown Error" }, /* 31 */
 };
 
-static const char * const dpp_rx_err = "Read Rx Descriptor Parity checker Error";
-static const char * const dpp_tx_err = "Read Tx Descriptor Parity checker Error";
+#define DPP_RX_ERR "Read Rx Descriptor Parity checker Error"
+#define DPP_TX_ERR "Read Tx Descriptor Parity checker Error"
+
 static const struct dwxgmac3_error_desc dwxgmac3_dma_dpp_errors[32] = {
-	{ true, "TDPES0", dpp_tx_err },
-	{ true, "TDPES1", dpp_tx_err },
-	{ true, "TDPES2", dpp_tx_err },
-	{ true, "TDPES3", dpp_tx_err },
-	{ true, "TDPES4", dpp_tx_err },
-	{ true, "TDPES5", dpp_tx_err },
-	{ true, "TDPES6", dpp_tx_err },
-	{ true, "TDPES7", dpp_tx_err },
-	{ true, "TDPES8", dpp_tx_err },
-	{ true, "TDPES9", dpp_tx_err },
-	{ true, "TDPES10", dpp_tx_err },
-	{ true, "TDPES11", dpp_tx_err },
-	{ true, "TDPES12", dpp_tx_err },
-	{ true, "TDPES13", dpp_tx_err },
-	{ true, "TDPES14", dpp_tx_err },
-	{ true, "TDPES15", dpp_tx_err },
-	{ true, "RDPES0", dpp_rx_err },
-	{ true, "RDPES1", dpp_rx_err },
-	{ true, "RDPES2", dpp_rx_err },
-	{ true, "RDPES3", dpp_rx_err },
-	{ true, "RDPES4", dpp_rx_err },
-	{ true, "RDPES5", dpp_rx_err },
-	{ true, "RDPES6", dpp_rx_err },
-	{ true, "RDPES7", dpp_rx_err },
-	{ true, "RDPES8", dpp_rx_err },
-	{ true, "RDPES9", dpp_rx_err },
-	{ true, "RDPES10", dpp_rx_err },
-	{ true, "RDPES11", dpp_rx_err },
-	{ true, "RDPES12", dpp_rx_err },
-	{ true, "RDPES13", dpp_rx_err },
-	{ true, "RDPES14", dpp_rx_err },
-	{ true, "RDPES15", dpp_rx_err },
+	{ true, "TDPES0", DPP_TX_ERR },
+	{ true, "TDPES1", DPP_TX_ERR },
+	{ true, "TDPES2", DPP_TX_ERR },
+	{ true, "TDPES3", DPP_TX_ERR },
+	{ true, "TDPES4", DPP_TX_ERR },
+	{ true, "TDPES5", DPP_TX_ERR },
+	{ true, "TDPES6", DPP_TX_ERR },
+	{ true, "TDPES7", DPP_TX_ERR },
+	{ true, "TDPES8", DPP_TX_ERR },
+	{ true, "TDPES9", DPP_TX_ERR },
+	{ true, "TDPES10", DPP_TX_ERR },
+	{ true, "TDPES11", DPP_TX_ERR },
+	{ true, "TDPES12", DPP_TX_ERR },
+	{ true, "TDPES13", DPP_TX_ERR },
+	{ true, "TDPES14", DPP_TX_ERR },
+	{ true, "TDPES15", DPP_TX_ERR },
+	{ true, "RDPES0", DPP_RX_ERR },
+	{ true, "RDPES1", DPP_RX_ERR },
+	{ true, "RDPES2", DPP_RX_ERR },
+	{ true, "RDPES3", DPP_RX_ERR },
+	{ true, "RDPES4", DPP_RX_ERR },
+	{ true, "RDPES5", DPP_RX_ERR },
+	{ true, "RDPES6", DPP_RX_ERR },
+	{ true, "RDPES7", DPP_RX_ERR },
+	{ true, "RDPES8", DPP_RX_ERR },
+	{ true, "RDPES9", DPP_RX_ERR },
+	{ true, "RDPES10", DPP_RX_ERR },
+	{ true, "RDPES11", DPP_RX_ERR },
+	{ true, "RDPES12", DPP_RX_ERR },
+	{ true, "RDPES13", DPP_RX_ERR },
+	{ true, "RDPES14", DPP_RX_ERR },
+	{ true, "RDPES15", DPP_RX_ERR },
 };
 
 static void dwxgmac3_handle_dma_err(struct net_device *ndev,


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Re: [PATCH net] net: stmmac: xgmac: use #define for string constants

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 08 Feb 2024 09:48:27 +0000 you wrote:
> The cited commit introduces and uses the string constants dpp_tx_err and
> dpp_rx_err. These are assigned to constant fields of the array
> dwxgmac3_error_desc.
> 
> It has been reported that on GCC 6 and 7.5.0 this results in warnings
> such as:
> 
> [...]

Here is the summary with links:
  - [net] net: stmmac: xgmac: use #define for string constants
    https://git.kernel.org/netdev/net/c/1692b9775e74

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html



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Re: [PATCH net] net: stmmac: xgmac: use #define for string constants

[Jiri Slaby]

On 08. 02. 24, 10:48, Simon Horman wrote:
> The cited commit introduces and uses the string constants dpp_tx_err and
> dpp_rx_err. These are assigned to constant fields of the array
> dwxgmac3_error_desc.
> 
> It has been reported that on GCC 6 and 7.5.0 this results in warnings
> such as:
> 
>    .../dwxgmac2_core.c:836:20: error: initialiser element is not constant
>     { true, "TDPES0", dpp_tx_err },
> 
> I have been able to reproduce this using: GCC 7.5.0, 8.4.0, 9.4.0 and 10.5.0.
> But not GCC 13.2.0.
> 
> So it seems this effects older compilers but not newer ones.
> As Jon points out in his report, the minimum compiler supported by
> the kernel is GCC 5.1, so it does seem that this ought to be fixed.
> 
> It is not clear to me what combination of 'const', if any, would address
> this problem.

You cannot make it more const than it is now ;). (You have a const 
pointer to const data already.)

> So this patch takes of using #defines for the string
> constants

That's indeed ugly. What about NOT creating a pointer to an array at 
all? See below.

> Compile tested only.
> 
> Fixes: 46eba193d04f ("net: stmmac: xgmac: fix handling of DPP safety error for DMA channels")
> Reported-by: Jon Hunter <jonathanh@nvidia.com>
> Closes: https://lore.kernel.org/netdev/c25eb595-8d91-40ea-9f52-efa15ebafdbc@nvidia.com/
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202402081135.lAxxBXHk-lkp@intel.com/
> Signed-off-by: Simon Horman <horms@kernel.org>
> ---
>   .../net/ethernet/stmicro/stmmac/dwxgmac2_core.c    | 69 +++++++++++-----------
>   1 file changed, 35 insertions(+), 34 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
> index 323c57f03c93..1af2f89a0504 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
> @@ -830,41 +830,42 @@ static const struct dwxgmac3_error_desc dwxgmac3_dma_errors[32]= {
>   	{ false, "UNKNOWN", "Unknown Error" }, /* 31 */
>   };
>   
> -static const char * const dpp_rx_err = "Read Rx Descriptor Parity checker Error";
> -static const char * const dpp_tx_err = "Read Tx Descriptor Parity checker Error";

The usual (even documented, I believe) way to do this is:

static const char dpp_tx_err[] = "Read Tx Descriptor Parity checker Error";

Then keep:
{ true, "TDPES0", dpp_tx_err },

Doesn't it do the right job?

> +#define DPP_RX_ERR "Read Rx Descriptor Parity checker Error"
> +#define DPP_TX_ERR "Read Tx Descriptor Parity checker Error"

thanks,
-- 
js
suse labs


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