From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH #upstream-fixes] libata: fix unexpectedly frozen port after ata_eh_reset() Date: Wed, 25 May 2011 12:02:32 +0200 Message-ID: <20110525100232.GG10146@htj.dyndns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-fx0-f46.google.com ([209.85.161.46]:44529 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751892Ab1EYKCg (ORCPT ); Wed, 25 May 2011 06:02:36 -0400 Received: by fxm17 with SMTP id 17so5237091fxm.19 for ; Wed, 25 May 2011 03:02:35 -0700 (PDT) Content-Disposition: inline Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Garzik Cc: linux-ide@vger.kernel.org, Bruce Stenning To work around controllers which can't properly plug events while reset, ata_eh_reset() clears error states and ATA_PFLAG_EH_PENDING after reset but before RESET is marked done. As reset is the final recovery action and full verification of devices including onlineness and classfication match is done afterwards, this shouldn't lead to lost devices or missed hotplug events. Unfortunately, it forgot to thaw the port when clearing EH_PENDING, so if the condition happens after resetting an empty port, the port could be left frozen and EH will end without thawing it, making the port unresponsive to further hotplug events. Thaw if the port is frozen after clearing EH_PENDING. This problem is reported by Bruce Stenning in the following thread. http://thread.gmane.org/gmane.linux.kernel/1123265 stable: I think we should weather this patch a bit longer in -rcX before sending it to -stable. Please wait at least a month after this patch makes upstream. Thanks. Signed-off-by: Tejun Heo Reported-by: Bruce Stenning Cc: stable@kernel.org --- drivers/ata/libata-eh.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c index dfb6e9d..094ce48 100644 --- a/drivers/ata/libata-eh.c +++ b/drivers/ata/libata-eh.c @@ -2802,10 +2802,11 @@ int ata_eh_reset(struct ata_link *link, int classify, } /* - * Some controllers can't be frozen very well and may set - * spuruious error conditions during reset. Clear accumulated - * error information. As reset is the final recovery action, - * nothing is lost by doing this. + * Some controllers can't be frozen very well and may set spuruious + * error conditions during reset. Clear accumulated error + * information and re-thaw the port if frozen. As reset is the + * final recovery action and we cross check link onlineness against + * device classification later, no hotplug event is lost by this. */ spin_lock_irqsave(link->ap->lock, flags); memset(&link->eh_info, 0, sizeof(link->eh_info)); @@ -2814,6 +2815,9 @@ int ata_eh_reset(struct ata_link *link, int classify, ap->pflags &= ~ATA_PFLAG_EH_PENDING; spin_unlock_irqrestore(link->ap->lock, flags); + if (ap->pflags & ATA_PFLAG_FROZEN) + ata_eh_thaw_port(ap); + /* * Make sure onlineness and classification result correspond. * Hotplug could have happened during reset and some