Re: [BUG] scsi: hpsa: how to destroy your files

From: Jon Mason <mason@myri.com>
To: scameron@beardog.cce.hp.com
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
	stephenmcameron@gmail.com, thenzl@redhat.com,
	akpm@linux-foundation.org, mikem@beardog.cce.hp.com,
	linux-pci@vger.kernel.org, Roland Dreier <roland@purestorage.com>,
	James Bottomley <James.Bottomley@hansenpartnership.com>
Subject: Re: [BUG] scsi: hpsa: how to destroy your files
Date: Thu, 1 Sep 2011 16:50:45 -0500	[thread overview]
Message-ID: <CAMaF-rOG9gNf3g8rOXiKMq3TXrfJf5dFwN6q6uQqvMruUm4VQg@mail.gmail.com> (raw)
In-Reply-To: <20110901204419.GY8422@beardog.cce.hp.com>

[-- Attachment #1: Type: text/plain, Size: 2295 bytes --]

On Thu, Sep 1, 2011 at 3:44 PM,  <scameron@beardog.cce.hp.com> wrote:
> On Thu, Sep 01, 2011 at 01:09:30PM -0700, Jesse Barnes wrote:
>> On Thu, 1 Sep 2011 15:03:49 -0500
>> scameron@beardog.cce.hp.com wrote:
>>
>> > On Thu, Sep 01, 2011 at 12:59:38PM -0700, Jesse Barnes wrote:
>> > > On Thu, 01 Sep 2011 11:50:38 -0700
>> > > James Bottomley <James.Bottomley@HansenPartnership.com> wrote:
>> > >
>> > > > On Thu, 2011-09-01 at 10:58 -0700, Roland Dreier wrote:
>> > > > > > OK I found the bad commit,I got lucky... I lost some files but my
>> > > > > > machine was able to complete the bisection. CC involved people
>> > > > >
>> > > > > > # bad: [b03e7495a862b028294f59fc87286d6d78ee7fa1] PCI: Set PCI-E Max Payload Size on fabric
>> > > > >
>> > > > > Hi Eric,
>> > > > >
>> > > > > I guess it would be useful to see "lspci -vv" output with a "good" kernel
>> > > > > and with that bad patch applied.  Most likely we should see some difference
>> > > > > somewhere in the MaxPayload fields in the PCI Express capability of
>> > > > > some device.
>> > > > >
>> > > > > Either the RAID controller or something else lies, and puts a value
>> > > > > in the DevCap that it can't actually support, or else the patch is
>> > > > > buggy and puts something out of range in a DevCtl somewhere.
>> > > >
>> > > >
>> > > > While we investigate, I think the problems produced by the patch (data
>> > > > corruption) are serious enough to warrant reverting it, please Jesse.
>> > >
>> > > Hm I haven't been paying attention to the compromise thread; how should
>> > > I share these changes?  Is master.kernel.org down indefinitely?  Is
>> > > there a new server at kernel.org I can use?
>> >
>> > I can't answer that question, but I would like a copy of your revert
>> > patch(es) to test (as a simple patch --reverse of the original commit on the 3.1-rc4
>> > tree didn't go in cleanly).
>>
>> Attached is the series.  Applies on top of my for-linus branch.
>
> Thanks.  I tried them out vs. 3.1-rc4, and they applied cleanly and
> make things work on my BL460g7.

I believe modifying the MRRS values is what is causing the issues.
Can you try the attached patch and verify that it also resolves the
issue?

Thanks,
Jon

> -- steve
>
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[-- Attachment #2: mrrs_removal.patch --]
[-- Type: text/x-patch, Size: 1848 bytes --]

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 8473727..d896c5e 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1394,41 +1394,6 @@ static void pcie_write_mps(struct pci_dev *dev, int mps)
 		dev_err(&dev->dev, "Failed attempting to set the MPS\n");
 }
 
-static void pcie_write_mrrs(struct pci_dev *dev, int mps)
-{
-	int rc, mrrs;
-
-	if (pcie_bus_config == PCIE_BUS_PERFORMANCE) {
-		int dev_mpss = 128 << dev->pcie_mpss;
-
-		/* For Max performance, the MRRS must be set to the largest
-		 * supported value.  However, it cannot be configured larger
-		 * than the MPS the device or the bus can support.  This assumes
-		 * that the largest MRRS available on the device cannot be
-		 * smaller than the device MPSS.
-		 */
-		mrrs = mps < dev_mpss ? mps : dev_mpss;
-	} else
-		/* In the "safe" case, configure the MRRS for fairness on the
-		 * bus by making all devices have the same size
-		 */
-		mrrs = mps;
-
-
-	/* MRRS is a R/W register.  Invalid values can be written, but a
-	 * subsiquent read will verify if the value is acceptable or not.
-	 * If the MRRS value provided is not acceptable (e.g., too large),
-	 * shrink the value until it is acceptable to the HW.
- 	 */
-	while (mrrs != pcie_get_readrq(dev) && mrrs >= 128) {
-		rc = pcie_set_readrq(dev, mrrs);
-		if (rc)
-			dev_err(&dev->dev, "Failed attempting to set the MRRS\n");
-
-		mrrs /= 2;
-	}
-}
-
 static int pcie_bus_configure_set(struct pci_dev *dev, void *data)
 {
 	int mps = 128 << *(u8 *)data;
@@ -1440,7 +1405,6 @@ static int pcie_bus_configure_set(struct pci_dev *dev, void *data)
 		 pcie_get_mps(dev), 128<<dev->pcie_mpss, pcie_get_readrq(dev));
 
 	pcie_write_mps(dev, mps);
-	pcie_write_mrrs(dev, mps);
 
 	dev_info(&dev->dev, "Dev MPS %d MPSS %d MRRS %d\n",
 		 pcie_get_mps(dev), 128<<dev->pcie_mpss, pcie_get_readrq(dev));
