From f7d8ad81ca8c447124821e58f876d1aff996c85f Mon Sep 17 00:00:00 2001 From: Karl Beldan Date: Wed, 13 Nov 2013 10:54:19 +0100 Subject: [PATCH] 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 Signed-off-by: Johannes Berg --- net/mac80211/rc80211_minstrel.c | 3 +-- net/mac80211/rc80211_minstrel_ht.c | 3 +-- 2 files changed, 2 insertions(+), 4 deletions(-) diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c index 7fa1b36..d2f19f7 100644 --- a/net/mac80211/rc80211_minstrel.c +++ b/net/mac80211/rc80211_minstrel.c @@ -422,10 +422,9 @@ init_sample_table(struct minstrel_sta_info *mi) memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates); for (col = 0; col < SAMPLE_COLUMNS; col++) { + prandom_bytes(rnd, sizeof(rnd)); for (i = 0; i < mi->n_rates; i++) { - get_random_bytes(rnd, sizeof(rnd)); new_idx = (i + rnd[i & 7]) % mi->n_rates; - while (SAMPLE_TBL(mi, new_idx, col) != 0xff) new_idx = (new_idx + 1) % mi->n_rates; 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 @@ init_sample_table(void) 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; -- 2.7.4