subject:"\[PATCH\] \[v2\] hinic\: avoid gcc \-Wrestrict warning"

Re: [PATCH] [v2] hinic: avoid gcc -Wrestrict warning

2021-03-24 Thread patchwork-bot+netdevbpf

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Wed, 24 Mar 2021 14:07:22 +0100 you wrote:
> From: Arnd Bergmann 
> 
> With extra warnings enabled, gcc complains that snprintf should not
> take the same buffer as source and destination:
> 
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c: In function 
> 'hinic_set_settings_to_hw':
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:480:9: error: 'snprintf' 
> argument 4 overlaps destination object 'set_link_str' [-Werror=restrict]
>   480 |   err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
>   | ^~~~
>   481 |   "%sspeed %d ", set_link_str, speed);
>   |   ~~~
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:464:7: note: destination 
> object referenced by 'restrict'-qualified argument 1 was declared here
>   464 |  char set_link_str[SET_LINK_STR_MAX_LEN] = {0};
> 
> [...]

Here is the summary with links:
  - [v2] hinic: avoid gcc -Wrestrict warning
https://git.kernel.org/netdev/net-next/c/84c7f6c33f42

You are awesome, thank you!
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Re: [PATCH] [v2] hinic: avoid gcc -Wrestrict warning

2021-03-24 Thread Arnd Bergmann

On Wed, Mar 24, 2021 at 2:29 PM Rasmus Villemoes
 wrote:
> On 24/03/2021 14.07, Arnd Bergmann wrote:
 >
> >   if (set_settings & HILINK_LINK_SET_SPEED) {
> >   speed_level = hinic_ethtool_to_hw_speed_level(speed);
> >   err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
> > -"%sspeed %d ", set_link_str, speed);
> > - if (err <= 0 || err >= SET_LINK_STR_MAX_LEN) {
> > +"speed %d ", speed);
> > + if (err >= SET_LINK_STR_MAX_LEN) {
> >   netif_err(nic_dev, drv, netdev, "Failed to snprintf 
> > link speed, function return(%d) and dest_len(%d)\n",
> > err, SET_LINK_STR_MAX_LEN);
> >   return -EFAULT;
>
> It's not your invention of course, but this both seems needlessly harsh
> and EFAULT is a weird error to return. It's just a printk() message that
> might be truncated, and now that the format string only has a %d
> specifier, it can actually be verified statically that overflow will
> never happen (though I don't know or think gcc can do that, perhaps
> there's some locale nonsense in the standard that allows using
> utf16-encoded sanskrit runes). So probably that test should just be
> dropped, but that's a separate thing.

I thought about fixing it, but this seemed to be a rabbit hole I didn't
want to get into, as there are other harmless issues in the driver
that could be improved.

I'm fairly sure gcc can indeed warn about the overflow with
-Wformat-truncation, but the warning is disabled at the moment
because it has a ton of false positives:

kernel/workqueue.c: In function 'create_worker':
kernel/workqueue.c:1933:55: error: '%d' directive output may be
truncated writing between 1 and 10 bytes into a region of size between
3 and 13 [-Werror=format-truncation=]
 1933 | snprintf(id_buf, sizeof(id_buf), "u%d:%d",
pool->id, id);

Arnd

Re: [PATCH] [v2] hinic: avoid gcc -Wrestrict warning

2021-03-24 Thread Rasmus Villemoes

On 24/03/2021 14.07, Arnd Bergmann wrote:
> From: Arnd Bergmann 
> 
> With extra warnings enabled, gcc complains that snprintf should not
> take the same buffer as source and destination:
> 
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c: In function 
> 'hinic_set_settings_to_hw':
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:480:9: error: 'snprintf' 
> argument 4 overlaps destination object 'set_link_str' [-Werror=restrict]
>   480 |   err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
>   | ^~~~
>   481 |   "%sspeed %d ", set_link_str, speed);
>   |   ~~~
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:464:7: note: destination 
> object referenced by 'restrict'-qualified argument 1 was declared here
>   464 |  char set_link_str[SET_LINK_STR_MAX_LEN] = {0};
> 
> Rewrite this to avoid the nested sprintf and instead use separate
> buffers, which is simpler.
> 

This looks much better. Thanks.

> Cc: Rasmus Villemoes 
> Signed-off-by: Arnd Bergmann 
> ---
> v2: rework according to feedback from Rasmus. This one could
> easily avoid most of the pitfalls
> ---
>  .../net/ethernet/huawei/hinic/hinic_ethtool.c | 25 ---
>  1 file changed, 10 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c 
> b/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
> index c340d9acba80..d7e20dab6e48 100644
> --- a/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
> +++ b/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
> @@ -34,7 +34,7 @@
>  #include "hinic_rx.h"
>  #include "hinic_dev.h"
>  
> -#define SET_LINK_STR_MAX_LEN 128
> +#define SET_LINK_STR_MAX_LEN 16
>  
>  #define GET_SUPPORTED_MODE   0
>  #define GET_ADVERTISED_MODE  1
> @@ -462,24 +462,19 @@ static int hinic_set_settings_to_hw(struct hinic_dev 
> *nic_dev,
>  {
>   struct hinic_link_ksettings_info settings = {0};
>   char set_link_str[SET_LINK_STR_MAX_LEN] = {0};
> + const char *autoneg_str;
>   struct net_device *netdev = nic_dev->netdev;
>   enum nic_speed_level speed_level = 0;
>   int err;
>  
> - err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN, "%s",
> -(set_settings & HILINK_LINK_SET_AUTONEG) ?
> -(autoneg ? "autong enable " : "autong disable ") : "");
> - if (err < 0 || err >= SET_LINK_STR_MAX_LEN) {
> - netif_err(nic_dev, drv, netdev, "Failed to snprintf link state, 
> function return(%d) and dest_len(%d)\n",
> -   err, SET_LINK_STR_MAX_LEN);
> - return -EFAULT;
> - }
> + autoneg_str = (set_settings & HILINK_LINK_SET_AUTONEG) ?
> +   (autoneg ? "autong enable " : "autong disable ") : "";
>  
>   if (set_settings & HILINK_LINK_SET_SPEED) {
>   speed_level = hinic_ethtool_to_hw_speed_level(speed);
>   err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
> -"%sspeed %d ", set_link_str, speed);
> - if (err <= 0 || err >= SET_LINK_STR_MAX_LEN) {
> +"speed %d ", speed);
> + if (err >= SET_LINK_STR_MAX_LEN) {
>   netif_err(nic_dev, drv, netdev, "Failed to snprintf 
> link speed, function return(%d) and dest_len(%d)\n",
> err, SET_LINK_STR_MAX_LEN);
>   return -EFAULT;

It's not your invention of course, but this both seems needlessly harsh
and EFAULT is a weird error to return. It's just a printk() message that
might be truncated, and now that the format string only has a %d
specifier, it can actually be verified statically that overflow will
never happen (though I don't know or think gcc can do that, perhaps
there's some locale nonsense in the standard that allows using
utf16-encoded sanskrit runes). So probably that test should just be
dropped, but that's a separate thing.

Reviewed-by: Rasmus Villemoes

[PATCH] [v2] hinic: avoid gcc -Wrestrict warning

2021-03-24 Thread Arnd Bergmann

From: Arnd Bergmann 

With extra warnings enabled, gcc complains that snprintf should not
take the same buffer as source and destination:

drivers/net/ethernet/huawei/hinic/hinic_ethtool.c: In function 
'hinic_set_settings_to_hw':
drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:480:9: error: 'snprintf' 
argument 4 overlaps destination object 'set_link_str' [-Werror=restrict]
  480 |   err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
  | ^~~~
  481 |   "%sspeed %d ", set_link_str, speed);
  |   ~~~
drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:464:7: note: destination 
object referenced by 'restrict'-qualified argument 1 was declared here
  464 |  char set_link_str[SET_LINK_STR_MAX_LEN] = {0};

Rewrite this to avoid the nested sprintf and instead use separate
buffers, which is simpler.

Cc: Rasmus Villemoes 
Signed-off-by: Arnd Bergmann 
---
v2: rework according to feedback from Rasmus. This one could
easily avoid most of the pitfalls
---
 .../net/ethernet/huawei/hinic/hinic_ethtool.c | 25 ---
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c 
b/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
index c340d9acba80..d7e20dab6e48 100644
--- a/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
+++ b/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
@@ -34,7 +34,7 @@
 #include "hinic_rx.h"
 #include "hinic_dev.h"
 
-#define SET_LINK_STR_MAX_LEN   128
+#define SET_LINK_STR_MAX_LEN   16
 
 #define GET_SUPPORTED_MODE 0
 #define GET_ADVERTISED_MODE1
@@ -462,24 +462,19 @@ static int hinic_set_settings_to_hw(struct hinic_dev 
*nic_dev,
 {
struct hinic_link_ksettings_info settings = {0};
char set_link_str[SET_LINK_STR_MAX_LEN] = {0};
+   const char *autoneg_str;
struct net_device *netdev = nic_dev->netdev;
enum nic_speed_level speed_level = 0;
int err;
 
-   err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN, "%s",
-  (set_settings & HILINK_LINK_SET_AUTONEG) ?
-  (autoneg ? "autong enable " : "autong disable ") : "");
-   if (err < 0 || err >= SET_LINK_STR_MAX_LEN) {
-   netif_err(nic_dev, drv, netdev, "Failed to snprintf link state, 
function return(%d) and dest_len(%d)\n",
- err, SET_LINK_STR_MAX_LEN);
-   return -EFAULT;
-   }
+   autoneg_str = (set_settings & HILINK_LINK_SET_AUTONEG) ?
+ (autoneg ? "autong enable " : "autong disable ") : "";
 
if (set_settings & HILINK_LINK_SET_SPEED) {
speed_level = hinic_ethtool_to_hw_speed_level(speed);
err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
-  "%sspeed %d ", set_link_str, speed);
-   if (err <= 0 || err >= SET_LINK_STR_MAX_LEN) {
+  "speed %d ", speed);
+   if (err >= SET_LINK_STR_MAX_LEN) {
netif_err(nic_dev, drv, netdev, "Failed to snprintf 
link speed, function return(%d) and dest_len(%d)\n",
  err, SET_LINK_STR_MAX_LEN);
return -EFAULT;
@@ -494,11 +489,11 @@ static int hinic_set_settings_to_hw(struct hinic_dev 
*nic_dev,
err = hinic_set_link_settings(nic_dev->hwdev, );
if (err != HINIC_MGMT_CMD_UNSUPPORTED) {
if (err)
-   netif_err(nic_dev, drv, netdev, "Set %s failed\n",
- set_link_str);
+   netif_err(nic_dev, drv, netdev, "Set %s%sfailed\n",
+ autoneg_str, set_link_str);
else
-   netif_info(nic_dev, drv, netdev, "Set %s 
successfully\n",
-  set_link_str);
+   netif_info(nic_dev, drv, netdev, "Set 
%s%ssuccessfully\n",
+  autoneg_str, set_link_str);
 
return err;
}
-- 
2.29.2

Re: [PATCH] [v2] hinic: avoid gcc -Wrestrict warning

Re: [PATCH] [v2] hinic: avoid gcc -Wrestrict warning

Re: [PATCH] [v2] hinic: avoid gcc -Wrestrict warning

[PATCH] [v2] hinic: avoid gcc -Wrestrict warning

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