2014-07-08 13:55:14

by Andrey Utkin

Subject: [PATCH] staging: rtl8192ee: Correct bitmask in comparsion

The issue is discovered by static checker. The proposed change (0x000c0
-> 0x000c) is likely correct because:
1. 16-bit `map` holds value coming from struct
ieee80211_vht_mcs_info.tx_mcs_map, which is described so: "TX MCS map 2
bits for each stream, total 8 streams". The changed code refers to case
of 2 TX streams, and 0x000c mask filters two bits related to the second
stream. Some codelines below 0x0003 mask is used to test first stream.
2. Mask 0x000c is used 3 more times in that place.
3. Specifying 5 digits of hex value is uncommon, especially while working
with `u16` variable. So likely the trailing zero is a typo.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=78041
Reported-by: David Binderman <[email protected]>
Signed-off-by: Andrey Utkin <[email protected]>
---
drivers/staging/rtl8192ee/base.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/rtl8192ee/base.c b/drivers/staging/rtl8192ee/base.c
index a7c69f7..71ed12e 100644
--- a/drivers/staging/rtl8192ee/base.c
+++ b/drivers/staging/rtl8192ee/base.c
@@ -827,7 +827,7 @@ static u8 _rtl_get_vht_highest_n_rate(struct ieee80211_hw *hw,
u16 map = le16_to_cpu(sta->vht_cap.vht_mcs.tx_mcs_map);

if ((get_rf_type(rtlphy) == RF_2T2R) &&
- (map & 0x000c) != 0x000c0) {
+ (map & 0x000c) != 0x000c) {
if ((map & 0x000c) >> 2 == IEEE80211_VHT_MCS_SUPPORT_0_7)
hw_rate =
rtlpriv->cfg->maps[RTL_RC_VHT_RATE_2SS_MCS7];
--
1.8.3.2

2014-07-08 15:07:59

by Dan Carpenter

Subject: Re: [PATCH] staging: rtl8192ee: Correct bitmask in comparsion

On Tue, Jul 08, 2014 at 04:54:59PM +0300, Andrey Utkin wrote:
> The issue is discovered by static checker. The proposed change (0x000c0
> -> 0x000c) is likely correct because:
> 1. 16-bit `map` holds value coming from struct
> ieee80211_vht_mcs_info.tx_mcs_map, which is described so: "TX MCS map 2
> bits for each stream, total 8 streams". The changed code refers to case
> of 2 TX streams, and 0x000c mask filters two bits related to the second
> stream. Some codelines below 0x0003 mask is used to test first stream.
> 2. Mask 0x000c is used 3 more times in that place.
> 3. Specifying 5 digits of hex value is uncommon, especially while working
> with `u16` variable. So likely the trailing zero is a typo.

This changelog is perfect. Thanks.

regards,
dan carpenter