Clang static checker warning:
Value stored to 'v1' is never read [deadcode.DeadStores]
Value stored to 'channel' is never read [deadcode.DeadStores]
Remove them to save some place.
Signed-off-by: Su Hui <[email protected]>
Acked-by: Ping-Ke Shih <[email protected]>
---
v3:
- same as v2.
v2:
- fix the subject prefix problem
drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c | 11 +----------
1 file changed, 1 insertion(+), 10 deletions(-)
diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c b/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c
index 5323ead30db0..6df270e29e66 100644
--- a/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c
+++ b/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c
@@ -2038,15 +2038,9 @@ static bool _rtl8821ae_phy_config_bb_with_pgheaderfile(struct ieee80211_hw *hw,
/*don't need the hw_body*/
if (!_rtl8821ae_check_condition(hw, v1)) {
i += 2; /* skip the pair of expression*/
- v1 = array[i];
v2 = array[i+1];
- v3 = array[i+2];
- while (v2 != 0xDEAD) {
+ while (v2 != 0xDEAD)
i += 3;
- v1 = array[i];
- v2 = array[i+1];
- v3 = array[i+2];
- }
}
}
}
@@ -3543,7 +3537,6 @@ u8 rtl8821ae_phy_sw_chnl(struct ieee80211_hw *hw)
struct rtl_phy *rtlphy = &rtlpriv->phy;
struct rtl_hal *rtlhal = rtl_hal(rtl_priv(hw));
u32 timeout = 1000, timecount = 0;
- u8 channel = rtlphy->current_channel;
if (rtlphy->sw_chnl_inprogress)
return 0;
@@ -3566,8 +3559,6 @@ u8 rtl8821ae_phy_sw_chnl(struct ieee80211_hw *hw)
rtl8821ae_phy_switch_wirelessband(hw, BAND_ON_2_4G);
rtlphy->sw_chnl_inprogress = true;
- if (channel == 0)
- channel = 1;
rtl_dbg(rtlpriv, COMP_SCAN, DBG_TRACE,
"switch to channel%d, band type is %d\n",
--
2.30.2
Clang staic checker warning:
drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c:184:49:
The result of the left shift is undefined due to shifting by '32',
which is greater or equal to the width of type 'u32'.
[core.UndefinedBinaryOperatorResult]
If the value of the right operand is negative or is greater than or
equal to the width of the promoted left operand, the behavior is
undefined.[1][2]
For example, when using different gcc's compilation optimizaation options
(-O0 or -O2), the result of '(u32)data << 32' is different. One is 0, the
other is old value of data. Let _rtl8821ae_phy_calculate_bit_shift()'s
return value less than 32 to fix this problem. Warn if bitmask is zero.
[1]:https://stackoverflow.com/questions/11270492/what-does-the-c-
standard-say-about-bitshifting-more-bits-than-the-width-of-type
[2]:https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf
Fixes: 21e4b0726dc6 ("rtlwifi: rtl8821ae: Move driver from staging to regular tree")
Signed-off-by: Su Hui <[email protected]>
---
v3:
- use __ffs() and make code briefer. (Thanks to Ping-Ke)
v2:
- fix the subject prefix problem
- silence the warning by not return 32 bits rather than adding a type cast.(Thanks to Dan and Ping-Ke)
drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c b/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c
index 6df270e29e66..68c3fb0395ce 100644
--- a/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c
+++ b/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c
@@ -29,9 +29,10 @@ static void _rtl8821ae_phy_rf_serial_write(struct ieee80211_hw *hw,
u32 data);
static u32 _rtl8821ae_phy_calculate_bit_shift(u32 bitmask)
{
- u32 i = ffs(bitmask);
+ if (WARN_ON_ONCE(!bitmask))
+ return 0;
- return i ? i - 1 : 32;
+ return __ffs(bitmask);
}
static bool _rtl8821ae_phy_bb8821a_config_parafile(struct ieee80211_hw *hw);
/*static bool _rtl8812ae_phy_config_mac_with_headerfile(struct ieee80211_hw *hw);*/
--
2.30.2
> -----Original Message-----
> From: Su Hui <[email protected]>
> Sent: Monday, November 27, 2023 9:35 AM
> To: Ping-Ke Shih <[email protected]>; [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]
> Cc: Su Hui <[email protected]>; [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]
> Subject: [PATCH wireless-next v3 2/2] wifi: rtlwifi: rtl8821ae: phy: fix an undefined bitwise shift behavior
>
> Clang staic checker warning:
> drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c:184:49:
> The result of the left shift is undefined due to shifting by '32',
> which is greater or equal to the width of type 'u32'.
> [core.UndefinedBinaryOperatorResult]
>
> If the value of the right operand is negative or is greater than or
> equal to the width of the promoted left operand, the behavior is
> undefined.[1][2]
>
> For example, when using different gcc's compilation optimizaation options
> (-O0 or -O2), the result of '(u32)data << 32' is different. One is 0, the
> other is old value of data. Let _rtl8821ae_phy_calculate_bit_shift()'s
> return value less than 32 to fix this problem. Warn if bitmask is zero.
>
> [1]:https://stackoverflow.com/questions/11270492/what-does-the-c-
> standard-say-about-bitshifting-more-bits-than-the-width-of-type
> [2]:https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf
>
> Fixes: 21e4b0726dc6 ("rtlwifi: rtl8821ae: Move driver from staging to regular tree")
> Signed-off-by: Su Hui <[email protected]>
Acked-by: Ping-Ke Shih <[email protected]>
> + if (WARN_ON_ONCE(!bitmask))
I test this patch with real hardware to connect 2GHz and 5GHz AP
respectively and keep ping for a while. It doesn't throw warning
by this statement.
Su Hui <[email protected]> wrote:
> Clang static checker warns:
>
> Value stored to 'v1' is never read [deadcode.DeadStores]
> Value stored to 'channel' is never read [deadcode.DeadStores]
>
> Remove them to save some place.
>
> Signed-off-by: Su Hui <[email protected]>
> Acked-by: Ping-Ke Shih <[email protected]>
2 patches applied to wireless-next.git, thanks.
cda37445718d wifi: rtlwifi: rtl8821ae: phy: remove some useless code
bc8263083af6 wifi: rtlwifi: rtl8821ae: phy: fix an undefined bitwise shift behavior
--
https://patchwork.kernel.org/project/linux-wireless/patch/[email protected]/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches