mac80211: minstrels: spare numerous useless calls to get_random_bytes
ATM, only the first array value returned by get_random_bytes is used.
This change moves the call to get_random_bytes from the nested loop it
is in to its parent.
While at it, replace get_random_bytes with prandom_bytes since PRNs are
way enough for the selection process.
After this, minstrel_ht reclaims 80 PR-bytes instead of 640 R-bytes.
minstrels use sample tables to probe different rates in a randomized
manner.
minstrel_ht inits one single sample table upon registration (during
subsys_initcalls) and minstrel uses one per STA addition in minstrel.
Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
index 0a4a7c7..e66e9f9 100644
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -1051,10 +1051,9 @@
memset(sample_table, 0xff, sizeof(sample_table));
for (col = 0; col < SAMPLE_COLUMNS; col++) {
+ prandom_bytes(rnd, sizeof(rnd));
for (i = 0; i < MCS_GROUP_RATES; i++) {
- get_random_bytes(rnd, sizeof(rnd));
new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
-
while (sample_table[col][new_idx] != 0xff)
new_idx = (new_idx + 1) % MCS_GROUP_RATES;