On Tue, Nov 12, 2013 at 09:36:15AM +0100, Johannes Berg wrote: > On Tue, 2013-11-12 at 01:37 +0100, Karl Beldan wrote: > > > > > 1) I'm pretty sure, but it would be good to get netdev confirmation, > > > > that the call to get_random_bytes() in > > > > net/mac80211/rc80211_minstrel.c's init_sample_table() can be replaced > > > > by calls to prandom_u32(). > > > > > > Would make sense. I added wireless-devel to confirm. > > > > > > [...] > > > [ 0.673260] random: rc80211_minstrel_ht_init+0x47/0xaa get_random_bytes called with 3 bits of entropy available > > > [ 0.674024] random: rc80211_minstrel_ht_init+0x47/0xaa get_random_bytes called with 3 bits of entropy available > > > [ 0.675012] random: rc80211_minstrel_ht_init+0x47/0xaa get_random_bytes called with 3 bits of entropy available > > > [ 0.676032] random: rc80211_minstrel_ht_init+0x47/0xaa get_random_bytes called with 3 bits of entropy available > > > [ 0.677020] random: rc80211_minstrel_ht_init+0x47/0xaa get_random_bytes called with 3 bits of entropy available > > > [ 0.678011] random: rc80211_minstrel_ht_init+0x47/0xaa get_random_bytes called with 3 bits of entropy available > > > [ 0.679011] random: rc80211_minstrel_ht_init+0x47/0xaa get_random_bytes called with 3 bits of entropy available > > > [...] > > > > > > In total 80 calls to get_random_bytes. > > > > > > > It is already 8 times what rc80211_minstrel_ht_init uses. > > If you could apply on top of: > > http://marc.info/?l=linux-wireless&m=138392850030987&w=2 > > although Johannes has not yet agreed/applied this. > > I'll take the patch, I just wanted a more useful commit log :) > The commit log still feels very right to me, but I don't want you to go grumpy ;) and will reword the log - Hannes, have you staged replacing get_random_bytes with prandom_u32 already or can I do it in a reworded v2 for minstrel ? > I guess if really needed I'll write that myself :( > > Anyway, I can't comment on prandom_u32(), but it doesn't really have to > be all that random here, it's just sample tables for what order to try > things in. Technically that could even be static with some per-device > pertubation, I guess? > The LFSR is way enough for minstrel, as for moving from prandom to handcrafted sample table, this will be another discussion I guess. Karl -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
