Since kernel 3.4, driver r8712u has yielded intermittent errors when connected
to a secure connection. With Firefox, the message is "Secure Connection Failed:
SSL received a record with an incorrect Message Authentication Code (Error code:
ssl_error_bad_mac_read)". A retry may work eventually, When using wget with an
https URL, the error message is "SSL3_GET_RECORD: decryption failed or bad
record mac".
This regression is the basis for https://bugzilla.kernel.org/show_bug.cgi?id=45071.
Although intermittent, I managed to bisect the problem. The bad commit is
==========================================================================
commit c8628155ece363487b57d33441ea0359018c0fa7
Author: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Date: Sun Mar 18 11:07:47 2012 +0000
tcp: reduce out_of_order memory use
With increasing receive window sizes, but speed of light not improved
that much, out of order queue can contain a huge number of skbs, waiting
to be moved to receive_queue when missing packets can fill the holes.
Some devices happen to use fat skbs (truesize of 4096 + sizeof(struct
sk_buff)) to store regular (MTU <= 1500) frames. This makes highly
probable sk_rmem_alloc hits sk_rcvbuf limit, which can be 4Mbytes in
many cases.
When limit is hit, tcp stack calls tcp_collapse_ofo_queue(), a true
latency killer and cpu cache blower.
Doing the coalescing attempt each time we add a frame in ofo queue
permits to keep memory use tight and in many cases avoid the
tcp_collapse() thing later.
Tested on various wireless setups (b43, ath9k, ...) known to use big skb
truesize, this patch removed the "packets collapsed in receive queue due
to low socket buffer" I had before.
This also reduced average memory used by tcp sockets.
With help from Neal Cardwell.
Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Cc: Neal Cardwell <ncardwell@xxxxxxxxxx>
Cc: Yuchung Cheng <ycheng@xxxxxxxxxx>
Cc: H.K. Jerry Chu <hkchu@xxxxxxxxxx>
Cc: Tom Herbert <therbert@xxxxxxxxxx>
Cc: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxx>
Acked-by: Neal Cardwell <ncardwell@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
============================================================================
As every other network driver is OK with this patch, I know the problem is in
r8712u. Do you have any thoughts on what it might be doing wrong to cause this
problem?
Thanks,
Larry
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