[PATCH] net: stmmac: Avoid sometimes uninitialized Clang warnings

[Nathan Chancellor]

When building with -Wsometimes-uninitialized, Clang warns:

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:495:3: warning: variable 'ns' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:495:3: warning: variable 'ns' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:532:3: warning: variable 'ns' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:532:3: warning: variable 'ns' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:741:3: warning: variable 'sec_inc' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:741:3: warning: variable 'sec_inc' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]

Clang is concerned with the use of stmmac_do_void_callback (which
stmmac_get_timestamp and stmmac_config_sub_second_increment wrap),
as it may fail to initialize these values if the if condition was ever
false (meaning the callbacks don't exist). It's not wrong because the
callbacks (get_timestamp and config_sub_second_increment respectively)
are the ones that initialize the variables. While it's unlikely that the
callbacks are ever going to disappear and make that condition false, we
can easily avoid this warning by zero initialize the variables.

Link: https://github.com/ClangBuiltLinux/linux/issues/384
Suggested-by: Nick Desaulniers <ndesau...@google.com>
Signed-off-by: Nathan Chancellor <natecha...@gmail.com>
---
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index e2a13ec2e30b..001a45aed273 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -480,7 +480,7 @@ static void stmmac_get_tx_hwtstamp(struct stmmac_priv *priv,
struct dma_desc *p, struct sk_buff *skb)
{
struct skb_shared_hwtstamps shhwtstamp;
- u64 ns;
+ u64 ns = 0;

if (!priv->hwts_tx_en)
return;
@@ -519,7 +519,7 @@ static void stmmac_get_rx_hwtstamp(struct stmmac_priv *priv, struct dma_desc *p,
{
struct skb_shared_hwtstamps *shhwtstamp = NULL;
struct dma_desc *desc = p;
- u64 ns;
+ u64 ns = 0;

if (!priv->hwts_rx_en)
return;
@@ -565,7 +565,7 @@ static int stmmac_hwtstamp_set(struct net_device *dev, struct ifreq *ifr)
u32 ts_master_en = 0;
u32 ts_event_en = 0;
u32 value = 0;
- u32 sec_inc;
+ u32 sec_inc = 0;
bool xmac;

xmac = priv->plat->has_gmac4 || priv->plat->has_xgmac;
--
2.21.0

[Nick Desaulniers]

On Thu, Mar 7, 2019 at 9:49 AM David Miller <da...@davemloft.net> wrote:

>
> From: Nathan Chancellor <natecha...@gmail.com>
> Date: Thu, 7 Mar 2019 09:21:01 -0700
>
> > @@ -565,7 +565,7 @@ static int stmmac_hwtstamp_set(struct net_device *dev, struct ifreq *ifr)
> > u32 ts_master_en = 0;
> > u32 ts_event_en = 0;
> > u32 value = 0;
> > - u32 sec_inc;
> > + u32 sec_inc = 0;
> > bool xmac;
>

> Please don't break the reverse christmas tree ordering here, thank you.

Every codebase has its own unique code style. *wonders how
clang-format could or could not handle that rule*

Thanks for sending the patch Nathan; if you could resend with the
declaration order changed so that the line width decreases going down
in the order, you can add my Reviewed-by tag.
--
Thanks,
~Nick Desaulniers

[Nathan Chancellor]

When building with -Wsometimes-uninitialized, Clang warns:

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:495:3: warning: variable 'ns' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:495:3: warning: variable 'ns' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:532:3: warning: variable 'ns' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:532:3: warning: variable 'ns' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:741:3: warning: variable 'sec_inc' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:741:3: warning: variable 'sec_inc' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]

Clang is concerned with the use of stmmac_do_void_callback (which
stmmac_get_timestamp and stmmac_config_sub_second_increment wrap),
as it may fail to initialize these values if the if condition was ever
false (meaning the callbacks don't exist). It's not wrong because the
callbacks (get_timestamp and config_sub_second_increment respectively)
are the ones that initialize the variables. While it's unlikely that the
callbacks are ever going to disappear and make that condition false, we
can easily avoid this warning by zero initialize the variables.

Link: https://github.com/ClangBuiltLinux/linux/issues/384
Suggested-by: Nick Desaulniers <ndesau...@google.com>

Reviewed-by: Nick Desaulniers <ndesau...@google.com>

Signed-off-by: Nathan Chancellor <natecha...@gmail.com>
---

v1 -> v2:

* Respect reverse Christmas tree variable ordering in
stmmac_hwtstamp_set.

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

index e2a13ec2e30b..97c5e1aad88f 100644

--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -480,7 +480,7 @@ static void stmmac_get_tx_hwtstamp(struct stmmac_priv *priv,
struct dma_desc *p, struct sk_buff *skb)
{
struct skb_shared_hwtstamps shhwtstamp;
- u64 ns;
+ u64 ns = 0;

if (!priv->hwts_tx_en)
return;
@@ -519,7 +519,7 @@ static void stmmac_get_rx_hwtstamp(struct stmmac_priv *priv, struct dma_desc *p,
{
struct skb_shared_hwtstamps *shhwtstamp = NULL;
struct dma_desc *desc = p;
- u64 ns;
+ u64 ns = 0;

if (!priv->hwts_rx_en)
return;

@@ -564,8 +564,8 @@ static int stmmac_hwtstamp_set(struct net_device *dev, struct ifreq *ifr)
u32 snap_type_sel = 0;

u32 ts_master_en = 0;
u32 ts_event_en = 0;

[Nick Desaulniers]

On Thu, Mar 7, 2019 at 10:00 AM Nathan Chancellor
<natecha...@gmail.com> wrote:
>
> When building with -Wsometimes-uninitialized, Clang warns:
>
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:495:3: warning: variable 'ns' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:495:3: warning: variable 'ns' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:532:3: warning: variable 'ns' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:532:3: warning: variable 'ns' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:741:3: warning: variable 'sec_inc' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:741:3: warning: variable 'sec_inc' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]
>
> Clang is concerned with the use of stmmac_do_void_callback (which
> stmmac_get_timestamp and stmmac_config_sub_second_increment wrap),
> as it may fail to initialize these values if the if condition was ever
> false (meaning the callbacks don't exist). It's not wrong because the
> callbacks (get_timestamp and config_sub_second_increment respectively)
> are the ones that initialize the variables. While it's unlikely that the
> callbacks are ever going to disappear and make that condition false, we
> can easily avoid this warning by zero initialize the variables.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/384
> Suggested-by: Nick Desaulniers <ndesau...@google.com>
> Reviewed-by: Nick Desaulniers <ndesau...@google.com>

V2 LGTM, thanks for resending.

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--
Thanks,
~Nick Desaulniers

[Nathan Chancellor]

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 <ndesau...@google.com>
Signed-off-by: Nathan Chancellor <natecha...@gmail.com>
---

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(&priv->ptp_lock, flags);
stmmac_get_systime(priv, priv->ptpaddr, &ns);
--
2.21.0

[Nick Desaulniers]

On Thu, Mar 7, 2019 at 8:02 PM Nathan Chancellor
<natecha...@gmail.com> 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 <ndesau...@google.com>

> Suggested-by: Nick Desaulniers <ndesau...@google.com>
> Signed-off-by: Nathan Chancellor <natecha...@gmail.com>
> ---
> 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(&priv->ptp_lock, flags);
> stmmac_get_systime(priv, priv->ptpaddr, &ns);
> --
> 2.21.0
>

--
Thanks,
~Nick Desaulniers

[David Miller]

From: Nathan Chancellor <natecha...@gmail.com>
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 <ndesau...@google.com>
> Signed-off-by: Nathan Chancellor <natecha...@gmail.com>

Applied, thanks Nathan.