| Message ID | 20190307180027.6226-1-natechancellor@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v2] net: stmmac: Avoid sometimes uninitialized Clang warnings | expand |
On Thu, Mar 7, 2019 at 10:00 AM Nathan Chancellor <natechancellor@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 <ndesaulniers@google.com> > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> V2 LGTM, thanks for resending. > Signed-off-by: Nathan Chancellor <natechancellor@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; > + u32 sec_inc = 0; > u32 value = 0; > - u32 sec_inc; > bool xmac; > > xmac = priv->plat->has_gmac4 || priv->plat->has_xgmac; > -- > 2.21.0 > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > To post to this group, send email to clang-built-linux@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20190307180027.6226-1-natechancellor%40gmail.com. > For more options, visit https://groups.google.com/d/optout.
From: Nathan Chancellor <natechancellor@gmail.com> Date: Thu, 7 Mar 2019 11:00:28 -0700 > 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 <ndesaulniers@google.com> > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Applied.
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; + u32 sec_inc = 0; u32 value = 0; - u32 sec_inc; bool xmac; xmac = priv->plat->has_gmac4 || priv->plat->has_xgmac;