Merge branch 'for-3.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata

Pull libata fixes from Tejun Heo:
 "There's one interseting commit - "libata, freezer: avoid block device
  removal while system is frozen".  It's an ugly hack working around a
  deadlock condition between driver core resume and block layer device
  removal paths through freezer which was made more reproducible by
  writeback being converted to workqueue some releases ago.  The bug has
  nothing to do with libata but it's just an workaround which is easy to
  backport.  After discussion, Rafael and I seem to agree that we don't
  really need kernel freezables - both kthread and workqueue.  There are
  few specific workqueues which constitute PM operations and require
  freezing, which will be converted to use workqueue_set_max_active()
  instead.  All other kernel freezer uses are planned to be removed,
  followed by the removal of kthread and workqueue freezer support,
  hopefully.

  Others are device-specific fixes.  The most notable is the addition of
  NO_NCQ_TRIM which is used to disable queued TRIM commands to Micro
  M500 SSDs which otherwise suffers data corruption"

* 'for-3.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
  libata, freezer: avoid block device removal while system is frozen
  libata: implement ATA_HORKAGE_NO_NCQ_TRIM and apply it to Micro M500 SSDs
  libata: disable a disk via libata.force params
  ahci: bail out on ICH6 before using AHCI BAR
  ahci: imx: Explicitly clear IMX6Q_GPR13_SATA_MPLL_CLK_EN
  libata: add ATA_HORKAGE_BROKEN_FPDMA_AA quirk for Seagate Momentus SpinPoint M8

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index ab58556d347c..377eb889f555 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3872,6 +3872,27 @@ void ata_scsi_hotplug(struct work_struct *work)
 		return;
 	}
 
+	/*
+	 * XXX - UGLY HACK
+	 *
+	 * The block layer suspend/resume path is fundamentally broken due
+	 * to freezable kthreads and workqueue and may deadlock if a block
+	 * device gets removed while resume is in progress.  I don't know
+	 * what the solution is short of removing freezable kthreads and
+	 * workqueues altogether.
+	 *
+	 * The following is an ugly hack to avoid kicking off device
+	 * removal while freezer is active.  This is a joke but does avoid
+	 * this particular deadlock scenario.
+	 *
+	 * https://bugzilla.kernel.org/show_bug.cgi?id=62801
+	 * http://marc.info/?l=linux-kernel&m=138695698516487
+	 */
+#ifdef CONFIG_FREEZER
+	while (pm_freezing)
+		msleep(10);
+#endif
+
 	DPRINTK("ENTER\n");
 	mutex_lock(&ap->scsi_scan_mutex);