[kernel] r16393 - in dists/lenny/linux-2.6/debian: . patches/bugfix/all patches/series

[Ben Hutchings]

Author: benh
Date: Sun Oct  3 19:18:54 2010
New Revision: 16393

Log:
SCSI/mptsas: fix hangs caused by ATA pass-through (Closes: #594690)

Added:
   dists/lenny/linux-2.6/debian/patches/bugfix/all/SCSI-mptsas-fix-hangs-caused-by-ATA-pass-through.patch
Modified:
   dists/lenny/linux-2.6/debian/changelog
   dists/lenny/linux-2.6/debian/patches/series/26

Modified: dists/lenny/linux-2.6/debian/changelog
==============================================================================
--- dists/lenny/linux-2.6/debian/changelog	Sun Oct  3 17:53:42 2010	(r16392)
+++ dists/lenny/linux-2.6/debian/changelog	Sun Oct  3 19:18:54 2010	(r16393)
@@ -3,6 +3,7 @@
   [ Ben Hutchings ]
   * [alpha,s390,sparc] math-emu: correct test for downshifting fraction in
     _FP_FROM_INT() (Closes: #593193)
+  * SCSI/mptsas: fix hangs caused by ATA pass-through (Closes: #594690)
 
  -- Ben Hutchings <ben at decadent.org.uk>  Thu, 09 Sep 2010 05:02:56 +0100
 

Added: dists/lenny/linux-2.6/debian/patches/bugfix/all/SCSI-mptsas-fix-hangs-caused-by-ATA-pass-through.patch
==============================================================================
--- /dev/null	00:00:00 1970	(empty, because file is newly added)
+++ dists/lenny/linux-2.6/debian/patches/bugfix/all/SCSI-mptsas-fix-hangs-caused-by-ATA-pass-through.patch	Sun Oct  3 19:18:54 2010	(r16393)
@@ -0,0 +1,77 @@
+From: Ryan Kuester <rkuester at kspace.net>
+Date: Mon, 26 Apr 2010 18:11:54 -0500
+Subject: [PATCH] [SCSI] mptsas: fix hangs caused by ATA pass-through
+
+commit 2a1b7e575b80ceb19ea50bfa86ce0053ea57181d upstream.
+
+I may have an explanation for the LSI 1068 HBA hangs provoked by ATA
+pass-through commands, in particular by smartctl.
+
+First, my version of the symptoms.  On an LSI SAS1068E B3 HBA running
+01.29.00.00 firmware, with SATA disks, and with smartd running, I'm seeing
+occasional task, bus, and host resets, some of which lead to hard faults of
+the HBA requiring a reboot.  Abusively looping the smartctl command,
+
+    # while true; do smartctl -a /dev/sdb > /dev/null; done
+
+dramatically increases the frequency of these failures to nearly one per
+minute.  A high IO load through the HBA while looping smartctl seems to
+improve the chance of a full scsi host reset or a non-recoverable hang.
+
+I reduced what smartctl was doing down to a simple test case which
+causes the hang with a single IO when pointed at the sd interface.  See
+the code at the bottom of this e-mail.  It uses an SG_IO ioctl to issue
+a single pass-through ATA identify device command.  If the buffer
+userspace gives for the read data has certain alignments, the task is
+issued to the HBA but the HBA fails to respond.  If run against the sg
+interface, neither the test code nor smartctl causes a hang.
+
+sd and sg handle the SG_IO ioctl slightly differently.  Unless you
+specifically set a flag to do direct IO, sg passes a buffer of its own,
+which is page-aligned, to the block layer and later copies the result
+into the userspace buffer regardless of its alignment.  sd, on the other
+hand, always does direct IO unless the userspace buffer fails an
+alignment test at block/blk-map.c line 57, in which case a page-aligned
+buffer is created and used for the transfer.
+
+The alignment test currently checks for word-alignment, the default
+setup by scsi_lib.c; therefore, userspace buffers of almost any
+alignment are given directly to the HBA as DMA targets.  The LSI 1068
+hardware doesn't seem to like at least a couple of the alignments which
+cross a page boundary (see the test code below).  Curiously, many
+page-boundary-crossing alignments do work just fine.
+
+So, either the hardware has an bug handling certain alignments or the
+hardware has a stricter alignment requirement than the driver is
+advertising.  If stricter alignment is required, then in no case should
+misaligned buffers from userspace be allowed through without being
+bounced or at least causing an error to be returned.
+
+It seems the mptsas driver could use blk_queue_dma_alignment() to advertise
+a stricter alignment requirement.  If it does, sd does the right thing and
+bounces misaligned buffers (see block/blk-map.c line 57).  The following
+patch to 2.6.34-rc5 makes my symptoms go away.  I'm sure this is the wrong
+place for this code, but it gets my idea across.
+
+Acked-by: "Desai, Kashyap" <Kashyap.Desai at lsi.com>
+Signed-off-by: James Bottomley <James.Bottomley at suse.de>
+---
+ drivers/message/fusion/mptscsih.c |    2 ++
+ 1 files changed, 2 insertions(+), 0 deletions(-)
+
+diff --git a/drivers/message/fusion/mptscsih.c b/drivers/message/fusion/mptscsih.c
+index 5c53624..407cb84 100644
+--- a/drivers/message/fusion/mptscsih.c
++++ b/drivers/message/fusion/mptscsih.c
+@@ -2459,6 +2459,8 @@ mptscsih_slave_configure(struct scsi_device *sdev)
+ 		ioc->name,sdev->tagged_supported, sdev->simple_tags,
+ 		sdev->ordered_tags));
+ 
++	blk_queue_dma_alignment (sdev->request_queue, 512 - 1);
++
+ 	return 0;
+ }
+ 
+-- 
+1.7.1
+

Modified: dists/lenny/linux-2.6/debian/patches/series/26
==============================================================================
--- dists/lenny/linux-2.6/debian/patches/series/26	Sun Oct  3 17:53:42 2010	(r16392)
+++ dists/lenny/linux-2.6/debian/patches/series/26	Sun Oct  3 19:18:54 2010	(r16393)
@@ -1 +1,2 @@
 + bugfix/all/math-emu-correct-test-for-downshifting-fraction.patch
++ bugfix/all/SCSI-mptsas-fix-hangs-caused-by-ATA-pass-through.patch