| Message ID | 20230329-net-ethernet-ti-wformat-v1-1-83d0f799b553@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 3292004c90c8aba74600a5cd8d10f8186fd48269 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] net: ethernet: ti: Fix format specifier in netcp_create_interface() | expand |
On Wed, Mar 29, 2023 at 8:08 AM Nathan Chancellor <nathan@kernel.org> wrote: > > After commit 3948b05950fd ("net: introduce a config option to tweak > MAX_SKB_FRAGS"), clang warns: > > drivers/net/ethernet/ti/netcp_core.c:2085:4: warning: format specifies type 'long' but the argument has type 'int' [-Wformat] > MAX_SKB_FRAGS); > ^~~~~~~~~~~~~ > include/linux/dev_printk.h:144:65: note: expanded from macro 'dev_err' > dev_printk_index_wrap(_dev_err, KERN_ERR, dev, dev_fmt(fmt), ##__VA_ARGS__) > ~~~ ^~~~~~~~~~~ > include/linux/dev_printk.h:110:23: note: expanded from macro 'dev_printk_index_wrap' > _p_func(dev, fmt, ##__VA_ARGS__); \ > ~~~ ^~~~~~~~~~~ > include/linux/skbuff.h:352:23: note: expanded from macro 'MAX_SKB_FRAGS' > #define MAX_SKB_FRAGS CONFIG_MAX_SKB_FRAGS > ^~~~~~~~~~~~~~~~~~~~ > ./include/generated/autoconf.h:11789:30: note: expanded from macro 'CONFIG_MAX_SKB_FRAGS' > #define CONFIG_MAX_SKB_FRAGS 17 > ^~ > 1 warning generated. > > Follow the pattern of the rest of the tree by changing the specifier to > '%u' and casting MAX_SKB_FRAGS explicitly to 'unsigned int', which > eliminates the warning. > > Fixes: 3948b05950fd ("net: introduce a config option to tweak MAX_SKB_FRAGS") > Signed-off-by: Nathan Chancellor <nathan@kernel.org> > --- > I am a little confused as to why the solution for this warning is > casting to 'unsigned int' rather than just updating all the specifiers > to be '%d', as I do not see how MAX_SKB_FRAGS can be any type other than > just 'int' but I figured I would be consistent with the other fixes I > have seen around this issue. MAX_SKB_FRAGS might be defined by Kconfig, see: 352 #define MAX_SKB_FRAGS CONFIG_MAX_SKB_FRAGS in include/linux/skbuff.h. The Kconfig is declared in net/Kconfig:254. Because integer literals in C are signed, the cast is necessary to avoid the format specifier from warning about the wrong signedness. It would be preferable to have a `U` suffix on the literal value, then the cast would be unnecessary. Untested: ``` diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 494a23a976b0..67cb6bfc4056 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -349,7 +349,7 @@ struct sk_buff; # define CONFIG_MAX_SKB_FRAGS 17 #endif -#define MAX_SKB_FRAGS CONFIG_MAX_SKB_FRAGS +#define MAX_SKB_FRAGS CONFIG_MAX_SKB_FRAGS ## U extern int sysctl_max_skb_frags; ``` Perhaps other code using MAX_SKB_FRAGS might have to worry about signedness and conversions. But I think what you have is fine for now. Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Though the above might be a longer-term solution since this might pop up again. > --- > drivers/net/ethernet/ti/netcp_core.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c > index 1bb596a9d8a2..d829113c16ee 100644 > --- a/drivers/net/ethernet/ti/netcp_core.c > +++ b/drivers/net/ethernet/ti/netcp_core.c > @@ -2081,8 +2081,8 @@ static int netcp_create_interface(struct netcp_device *netcp_device, > netcp->tx_pool_region_id = temp[1]; > > if (netcp->tx_pool_size < MAX_SKB_FRAGS) { > - dev_err(dev, "tx-pool size too small, must be at least %ld\n", > - MAX_SKB_FRAGS); > + dev_err(dev, "tx-pool size too small, must be at least %u\n", > + (unsigned int)MAX_SKB_FRAGS); > ret = -ENODEV; > goto quit; > } > > --- > base-commit: 3b064f541be822dc095991c6dda20a75eb51db5e > change-id: 20230329-net-ethernet-ti-wformat-acaa86350657 > > Best regards, > -- > Nathan Chancellor <nathan@kernel.org> >
On Wed, Mar 29, 2023 at 10:10 AM Nick Desaulniers <ndesaulniers@google.com> wrote: > > Because integer literals in C are signed, the cast is necessary to > avoid the format specifier from warning about the wrong signedness. > It would be preferable to have a `U` suffix on the literal value, then > the cast would be unnecessary. > > Untested: > ``` > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > index 494a23a976b0..67cb6bfc4056 100644 > --- a/include/linux/skbuff.h > +++ b/include/linux/skbuff.h > @@ -349,7 +349,7 @@ struct sk_buff; > # define CONFIG_MAX_SKB_FRAGS 17 > #endif > > -#define MAX_SKB_FRAGS CONFIG_MAX_SKB_FRAGS > +#define MAX_SKB_FRAGS CONFIG_MAX_SKB_FRAGS ## U Or rather this trick. https://godbolt.org/z/81aPxf39b I forget what that's called (it's not xmacros); we definitely have a macro for that in the kernel.
Hello: This patch was applied to netdev/net-next.git (main) by Jakub Kicinski <kuba@kernel.org>: On Wed, 29 Mar 2023 08:08:01 -0700 you wrote: > After commit 3948b05950fd ("net: introduce a config option to tweak > MAX_SKB_FRAGS"), clang warns: > > drivers/net/ethernet/ti/netcp_core.c:2085:4: warning: format specifies type 'long' but the argument has type 'int' [-Wformat] > MAX_SKB_FRAGS); > ^~~~~~~~~~~~~ > include/linux/dev_printk.h:144:65: note: expanded from macro 'dev_err' > dev_printk_index_wrap(_dev_err, KERN_ERR, dev, dev_fmt(fmt), ##__VA_ARGS__) > ~~~ ^~~~~~~~~~~ > include/linux/dev_printk.h:110:23: note: expanded from macro 'dev_printk_index_wrap' > _p_func(dev, fmt, ##__VA_ARGS__); \ > ~~~ ^~~~~~~~~~~ > include/linux/skbuff.h:352:23: note: expanded from macro 'MAX_SKB_FRAGS' > #define MAX_SKB_FRAGS CONFIG_MAX_SKB_FRAGS > ^~~~~~~~~~~~~~~~~~~~ > ./include/generated/autoconf.h:11789:30: note: expanded from macro 'CONFIG_MAX_SKB_FRAGS' > #define CONFIG_MAX_SKB_FRAGS 17 > ^~ > 1 warning generated. > > [...] Here is the summary with links: - [net-next] net: ethernet: ti: Fix format specifier in netcp_create_interface() https://git.kernel.org/netdev/net-next/c/3292004c90c8 You are awesome, thank you!
diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c index 1bb596a9d8a2..d829113c16ee 100644 --- a/drivers/net/ethernet/ti/netcp_core.c +++ b/drivers/net/ethernet/ti/netcp_core.c @@ -2081,8 +2081,8 @@ static int netcp_create_interface(struct netcp_device *netcp_device, netcp->tx_pool_region_id = temp[1]; if (netcp->tx_pool_size < MAX_SKB_FRAGS) { - dev_err(dev, "tx-pool size too small, must be at least %ld\n", - MAX_SKB_FRAGS); + dev_err(dev, "tx-pool size too small, must be at least %u\n", + (unsigned int)MAX_SKB_FRAGS); ret = -ENODEV; goto quit; }
After commit 3948b05950fd ("net: introduce a config option to tweak MAX_SKB_FRAGS"), clang warns: drivers/net/ethernet/ti/netcp_core.c:2085:4: warning: format specifies type 'long' but the argument has type 'int' [-Wformat] MAX_SKB_FRAGS); ^~~~~~~~~~~~~ include/linux/dev_printk.h:144:65: note: expanded from macro 'dev_err' dev_printk_index_wrap(_dev_err, KERN_ERR, dev, dev_fmt(fmt), ##__VA_ARGS__) ~~~ ^~~~~~~~~~~ include/linux/dev_printk.h:110:23: note: expanded from macro 'dev_printk_index_wrap' _p_func(dev, fmt, ##__VA_ARGS__); \ ~~~ ^~~~~~~~~~~ include/linux/skbuff.h:352:23: note: expanded from macro 'MAX_SKB_FRAGS' #define MAX_SKB_FRAGS CONFIG_MAX_SKB_FRAGS ^~~~~~~~~~~~~~~~~~~~ ./include/generated/autoconf.h:11789:30: note: expanded from macro 'CONFIG_MAX_SKB_FRAGS' #define CONFIG_MAX_SKB_FRAGS 17 ^~ 1 warning generated. Follow the pattern of the rest of the tree by changing the specifier to '%u' and casting MAX_SKB_FRAGS explicitly to 'unsigned int', which eliminates the warning. Fixes: 3948b05950fd ("net: introduce a config option to tweak MAX_SKB_FRAGS") Signed-off-by: Nathan Chancellor <nathan@kernel.org> --- I am a little confused as to why the solution for this warning is casting to 'unsigned int' rather than just updating all the specifiers to be '%d', as I do not see how MAX_SKB_FRAGS can be any type other than just 'int' but I figured I would be consistent with the other fixes I have seen around this issue. --- drivers/net/ethernet/ti/netcp_core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- base-commit: 3b064f541be822dc095991c6dda20a75eb51db5e change-id: 20230329-net-ethernet-ti-wformat-acaa86350657 Best regards,