From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752186AbaHaXZE (ORCPT ); Sun, 31 Aug 2014 19:25:04 -0400 Received: from icebox.esperi.org.uk ([81.187.191.129]:55883 "EHLO mail.esperi.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752020AbaHaXZD (ORCPT ); Sun, 31 Aug 2014 19:25:03 -0400 X-Greylist: delayed 1045 seconds by postgrey-1.27 at vger.kernel.org; Sun, 31 Aug 2014 19:25:02 EDT From: Nix To: oliver@neukum.org Cc: linux-kernel@vger.kernel.org Subject: [3.16.1 REGRESSION]: Simtec Entropy Key (cdc-acm) broken in 3.16 Emacs: resistance is futile; you will be assimilated and byte-compiled. Date: Mon, 01 Sep 2014 00:07:34 +0100 Message-ID: <878um4tg09.fsf@spindle.srvr.nix> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-DCC-wuwien-Metrics: spindle 1290; Body=2 Fuz1=2 Fuz2=2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org So I upgraded to 3.16.1 and found that the Simtec Entropy Key (a cdc-acm device) was no longer operational: fold:~# ekeydctl stats 1 BytesRead=0 BytesWritten=0 ConnectionNonces=0 ConnectionPackets=0 ConnectionRekeys=0 ConnectionResets=0 ConnectionTime=65 EntropyRate=0 FipsFrameRate=0 FrameByteLast=0 FramesOk=0 FramingErrors=0 KeyDbsdShannonPerByteL=0 KeyDbsdShannonPerByteR=0 KeyEnglishBadness=No failure KeyRawBadness=0 KeyRawShannonPerByteL=0 KeyRawShannonPerByteR=0 KeyRawShannonPerByteX=0 KeyShortBadness=efm_ok KeyTemperatureC=-273.15 KeyTemperatureF=-459.67 KeyTemperatureK=0 KeyVoltage=0 PacketErrors=0 PacketOK=0 ReadRate=0 TotalEntropy=0 WriteRate=0 This device streams data continuously at at rate of several KiB/s, so normally we would never expect to see a report of zero bytes read or written if the key were functional (nor, indeed, a key temperature of absolute zero!) It appears that cdc-acm has broken such that no data is received from this device any more (though it's still being detected, according to the dmesg log). Something goes very askew with the entropy key -- even after rebooting back to an earlier kernel, a physical disconnection and reconnection of the entropy key is needed to make it work again. Whether this is some sort of cdc-acm-level protocol problem, or a key-level problem caused by interrupted communication, I have no clue. 3.15.8 works fine. I'll do a bisection of the cdc-acm changes since 3.15 tomorrow night and see if I can find the commit at fault. -- NULL && (void)