Reported by the following Smatch static checker warning: drivers/net/dsa/yt921x.c:702 yt921x_read_mib() warn: was expecting a 64 bit value instead of '(~0)' Reported-by: Dan Carpenter Closes: https://lore.kernel.org/netdev/aPsjYKQMzpY0nSXm@stanley.mountain/ Suggested-by: David Laight Signed-off-by: David Yang --- drivers/net/dsa/yt921x.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/drivers/net/dsa/yt921x.c b/drivers/net/dsa/yt921x.c index ab762ffc4661..97a7eeb4ea15 100644 --- a/drivers/net/dsa/yt921x.c +++ b/drivers/net/dsa/yt921x.c @@ -687,21 +687,22 @@ static int yt921x_read_mib(struct yt921x_priv *priv, int port) const struct yt921x_mib_desc *desc = &yt921x_mib_descs[i]; u32 reg = YT921X_MIBn_DATA0(port) + desc->offset; u64 *valp = &((u64 *)mib)[i]; - u64 val = *valp; + u64 val; u32 val0; - u32 val1; res = yt921x_reg_read(priv, reg, &val0); if (res) break; if (desc->size <= 1) { - if (val < (u32)val) - /* overflow */ - val += (u64)U32_MAX + 1; - val &= ~U32_MAX; - val |= val0; + u64 old_val = *valp; + + val = (old_val & ~(u64)U32_MAX) | val0; + if (val < old_val) + val += 1ull << 32; } else { + u32 val1; + res = yt921x_reg_read(priv, reg + 4, &val1); if (res) break; -- 2.51.0