Re: [PATCH] b43: shut up clang -Wuninitialized variable warning

From: Larry Finger
Date: Fri Mar 22 2019 - 11:47:16 EST


On 3/22/19 9:37 AM, Arnd Bergmann wrote:
Clang warns about what is clearly a case of passing an uninitalized
variable into a static function:

drivers/net/wireless/broadcom/b43/phy_lp.c:1852:23: error: variable 'gains' is uninitialized when used here
[-Werror,-Wuninitialized]
lpphy_papd_cal(dev, gains, 0, 1, 30);
^~~~~
drivers/net/wireless/broadcom/b43/phy_lp.c:1838:2: note: variable 'gains' is declared here
struct lpphy_tx_gains gains, oldgains;
^
1 error generated.

However, this function is empty, and its arguments are never evaluated,
so gcc in contrast does not warn here. Both compilers behave in a
reasonable way as far as I can tell, so we should change the code
to avoid the warning everywhere.

We could just eliminate the lpphy_papd_cal() function entirely,
given that it has had the TODO comment in it for 10 years now
and is rather unlikely to ever get done. I'm doing a simpler
change here, and just pass the 'oldgains' variable in that has
been initialized, based on the guess that this is what was
originally meant.

Fixes: 2c0d6100da3e ("b43: LP-PHY: Begin implementing calibration & software RFKILL support")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/net/wireless/broadcom/b43/phy_lp.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/broadcom/b43/phy_lp.c b/drivers/net/wireless/broadcom/b43/phy_lp.c
index 46408a560814..aedee026c5e2 100644
--- a/drivers/net/wireless/broadcom/b43/phy_lp.c
+++ b/drivers/net/wireless/broadcom/b43/phy_lp.c
@@ -1835,7 +1835,7 @@ static void lpphy_papd_cal(struct b43_wldev *dev, struct lpphy_tx_gains gains,
static void lpphy_papd_cal_txpwr(struct b43_wldev *dev)
{
struct b43_phy_lp *lpphy = dev->phy.lp;
- struct lpphy_tx_gains gains, oldgains;
+ struct lpphy_tx_gains oldgains;
int old_txpctl, old_afe_ovr, old_rf, old_bbmult;
lpphy_read_tx_pctl_mode_from_hardware(dev);
@@ -1849,9 +1849,9 @@ static void lpphy_papd_cal_txpwr(struct b43_wldev *dev)
lpphy_set_tx_power_control(dev, B43_LPPHY_TXPCTL_OFF);
if (dev->dev->chip_id == 0x4325 && dev->dev->chip_rev == 0)
- lpphy_papd_cal(dev, gains, 0, 1, 30);
+ lpphy_papd_cal(dev, oldgains, 0, 1, 30);
else
- lpphy_papd_cal(dev, gains, 0, 1, 65);
+ lpphy_papd_cal(dev, oldgains, 0, 1, 65);
if (old_afe_ovr)
lpphy_set_tx_gains(dev, oldgains);


Acked-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>

Thanks. I will submit a patch that removes lpphy_papd_cal(). You are correct that it is unlikely ever to be implemented.

Larry