linux-kernel - Re: sata_mv port lockup on hotplug (kernel 2.6.38.2)

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Date:	Tue, 26 Apr 2011 15:50:27 +0200
From:	Tejun Heo <htejun@...il.com>
To:	Bruce Stenning <b.stenning@...igovision.com>
Cc:	Mark Lord <kernel@...savvy.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-ide@...r.kernel.org" <linux-ide@...r.kernel.org>
Subject: Re: sata_mv port lockup on hotplug (kernel 2.6.38.2)

On Tue, Apr 26, 2011 at 02:13:22PM +0100, Bruce Stenning wrote:
> Tejun wrote:
> > ata4 is reporting link down and the device is detached and port
> > disabled afterwards.  Doesn't seem to have much to do with
> > freezing/thawing?
> 
> After all processing of a normal unplug event has completed, the port is left
> thawed (and the irq enabled) to allow future hotplug events on this port to be
> actioned.  In the case of the port lockups that I have seen the port appears
> to be left frozen, with the irq disabled, and I am hypothesising that this is
> due to a race between the freeze and the thaw.
> 
> Below is some additional tracing leading up to a port lockup, with some more
> DPRINTK statements added.  The port freeze appears to be happening after the
> port thaw.  The irq mask writes that are output by mv_set_main_irq_mask seem
> to show the irqs left masked off.

Does the following patch resolve the problem?

Thanks.

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 88cd22f..73f0589 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2802,19 +2802,6 @@ 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.
-	 */
-	spin_lock_irqsave(link->ap->lock, flags);
-	memset(&link->eh_info, 0, sizeof(link->eh_info));
-	if (slave)
-		memset(&slave->eh_info, 0, sizeof(link->eh_info));
-	ap->pflags &= ~ATA_PFLAG_EH_PENDING;
-	spin_unlock_irqrestore(link->ap->lock, flags);
-
-	/*
 	 * Make sure onlineness and classification result correspond.
 	 * Hotplug could have happened during reset and some
 	 * controllers fail to wait while a drive is spinning up after
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