Re: [PATCH] net: stmmac: Avoid one more sometimes uninitialized Clang warning
From: Nathan Chancellor
Date: Thu, 7 Mar 2019 21:02:39 -0700
> When building with -Wsometimes-uninitialized, Clang warns:
>
> drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c:111:2: error: variable
> 'ns' is used uninitialized whenever 'if' condition is false
> [-Werror,-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c:111:2: error: variable
> 'ns' is used uninitialized whenever '&&' condition is false
> [-Werror,-Wsometimes-uninitialized]
>
> Clang is concerned with the use of stmmac_do_void_callback (which
> stmmac_get_systime wraps), as it may fail to initialize these values if
> the if condition was ever false (meaning the callback doesn't exist).
> It's not wrong because the callback is what initializes ns. While it's
> unlikely that the callback is going to disappear at some point and make
> that condition false, we can easily avoid this warning by zero
> initializing the variable.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/384
> Fixes: df103170854e ("net: stmmac: Avoid sometimes uninitialized Clang
> warnings")
> Suggested-by: Nick Desaulniers
> Signed-off-by: Nathan Chancellor
Applied, thanks Nathan.
Re: [PATCH] net: stmmac: Avoid one more sometimes uninitialized Clang warning
On Thu, Mar 7, 2019 at 8:02 PM Nathan Chancellor
wrote:
>
> When building with -Wsometimes-uninitialized, Clang warns:
>
> drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c:111:2: error: variable
> 'ns' is used uninitialized whenever 'if' condition is false
> [-Werror,-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c:111:2: error: variable
> 'ns' is used uninitialized whenever '&&' condition is false
> [-Werror,-Wsometimes-uninitialized]
>
> Clang is concerned with the use of stmmac_do_void_callback (which
> stmmac_get_systime wraps), as it may fail to initialize these values if
> the if condition was ever false (meaning the callback doesn't exist).
> It's not wrong because the callback is what initializes ns. While it's
> unlikely that the callback is going to disappear at some point and make
> that condition false, we can easily avoid this warning by zero
> initializing the variable.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/384
> Fixes: df103170854e ("net: stmmac: Avoid sometimes uninitialized Clang
> warnings")
Was initially confused by the link (thought I caught the 3 previous
instances in code review of df103170854e). I see now that I did not
report stmmac_ptp.c (only stmmac_main.c) properly. Had I, this could
have been bundled up into df103170854e indeed. Sorry. Thanks for
circling back and cleaning up this additional instance.
Reviewed-by: Nick Desaulniers
> Suggested-by: Nick Desaulniers
> Signed-off-by: Nathan Chancellor
> ---
> drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
> b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
> index 2293e21f789f..cc60b3fb0892 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
> @@ -105,7 +105,7 @@ static int stmmac_get_time(struct ptp_clock_info *ptp,
> struct timespec64 *ts)
> struct stmmac_priv *priv =
> container_of(ptp, struct stmmac_priv, ptp_clock_ops);
> unsigned long flags;
> - u64 ns;
> + u64 ns = 0;
>
> spin_lock_irqsave(>ptp_lock, flags);
> stmmac_get_systime(priv, priv->ptpaddr, );
> --
> 2.21.0
>
--
Thanks,
~Nick Desaulniers
[PATCH] net: stmmac: Avoid one more sometimes uninitialized Clang warning
When building with -Wsometimes-uninitialized, Clang warns:
drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c:111:2: error: variable
'ns' is used uninitialized whenever 'if' condition is false
[-Werror,-Wsometimes-uninitialized]
drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c:111:2: error: variable
'ns' is used uninitialized whenever '&&' condition is false
[-Werror,-Wsometimes-uninitialized]
Clang is concerned with the use of stmmac_do_void_callback (which
stmmac_get_systime wraps), as it may fail to initialize these values if
the if condition was ever false (meaning the callback doesn't exist).
It's not wrong because the callback is what initializes ns. While it's
unlikely that the callback is going to disappear at some point and make
that condition false, we can easily avoid this warning by zero
initializing the variable.
Link: https://github.com/ClangBuiltLinux/linux/issues/384
Fixes: df103170854e ("net: stmmac: Avoid sometimes uninitialized Clang
warnings")
Suggested-by: Nick Desaulniers
Signed-off-by: Nathan Chancellor
---
drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
index 2293e21f789f..cc60b3fb0892 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
@@ -105,7 +105,7 @@ static int stmmac_get_time(struct ptp_clock_info *ptp,
struct timespec64 *ts)
struct stmmac_priv *priv =
container_of(ptp, struct stmmac_priv, ptp_clock_ops);
unsigned long flags;
- u64 ns;
+ u64 ns = 0;
spin_lock_irqsave(>ptp_lock, flags);
stmmac_get_systime(priv, priv->ptpaddr, );
--
2.21.0
