net: stmmac: Avoid one more sometimes uninitialized Clang warning

BugLink: https://bugs.launchpad.net/bugs/1838116
[ Upstream commit 1f5d861f7fefa971b2c6e766f77932c86419a319 ]

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 <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
index e471a903c6543f8f29c817cc0f7c8b5c474e3cec..7fe0858b4715cb78183bd657231920daad4ddbf8 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
@@ -107,7 +107,7 @@ 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);