[openwrt/openwrt] mac80211: minstrel_ht: fix issue in calculating success probability

[LEDE Commits]

nbd pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/12cb52bd0665da33cb5dc64697f1751a8b33fb05

commit 12cb52bd0665da33cb5dc64697f1751a8b33fb05
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Wed Apr 28 21:06:36 2021 +0200

    mac80211: minstrel_ht: fix issue in calculating success probability
    
    Missing braces in a macro were leading to badly working rates sometimes
    getting a success probabilty of 1.0
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 ...c80211-minstrel_ht-fix-MINSTREL_FRAC-macro.patch | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/package/kernel/mac80211/patches/subsys/353-mac80211-minstrel_ht-fix-MINSTREL_FRAC-macro.patch b/package/kernel/mac80211/patches/subsys/353-mac80211-minstrel_ht-fix-MINSTREL_FRAC-macro.patch
new file mode 100644
index 0000000000..0d475b7329
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/353-mac80211-minstrel_ht-fix-MINSTREL_FRAC-macro.patch
@@ -0,0 +1,21 @@
+From: Felix Fietkau <nbd at nbd.name>
+Date: Wed, 28 Apr 2021 21:03:13 +0200
+Subject: [PATCH] mac80211: minstrel_ht: fix MINSTREL_FRAC macro
+
+Add missing braces to avoid issues with e.g. using additions in the
+div expression
+
+Signed-off-by: Felix Fietkau <nbd at nbd.name>
+---
+
+--- a/net/mac80211/rc80211_minstrel_ht.h
++++ b/net/mac80211/rc80211_minstrel_ht.h
+@@ -14,7 +14,7 @@
+ 
+ /* scaled fraction values */
+ #define MINSTREL_SCALE  12
+-#define MINSTREL_FRAC(val, div) (((val) << MINSTREL_SCALE) / div)
++#define MINSTREL_FRAC(val, div) (((val) << MINSTREL_SCALE) / (div))
+ #define MINSTREL_TRUNC(val) ((val) >> MINSTREL_SCALE)
+ 
+ #define EWMA_LEVEL	96	/* ewma weighting factor [/EWMA_DIV] */