libata: perform port detach in EH

ata_port_detach() first made sure EH saw ATA_PFLAG_UNLOADING and then
assumed EH context belongs to it and performed detach operation
itself.  However, UNLOADING doesn't disable all of EH and this could
lead to problems including triggering WARN_ON()'s in EH path.

This patch makes port detach behave more like other EH actions such
that ata_port_detach() requests EH to detach and waits for completion.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

3 files changed, 37 insertions, 21 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 1ecc3cb0b722..837fb60a6dcc 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6107,8 +6107,6 @@ int ata_host_activate(struct ata_host *host, int irq,
 static void ata_port_detach(struct ata_port *ap)
 {
         unsigned long flags;
-        struct ata_link *link;
-        struct ata_device *dev;
 
         if (!ap->ops->error_handler)
                 goto skip_eh;
@@ -6116,28 +6114,15 @@ static void ata_port_detach(struct ata_port *ap)
         /* tell EH we're leaving & flush EH */
         spin_lock_irqsave(ap->lock, flags);
         ap->pflags |= ATA_PFLAG_UNLOADING;
+        ata_port_schedule_eh(ap);
         spin_unlock_irqrestore(ap->lock, flags);
 
+        /* wait till EH commits suicide */
         ata_port_wait_eh(ap);
 
-        /* EH is now guaranteed to see UNLOADING - EH context belongs
-         * to us.  Restore SControl and disable all existing devices.
-         */
-        ata_for_each_link(link, ap, PMP_FIRST) {
-                sata_scr_write(link, SCR_CONTROL, link->saved_scontrol & 0xff0);
-                ata_for_each_dev(dev, link, ALL)
-                        ata_dev_disable(dev);
-        }
-
-        /* Final freeze & EH.  All in-flight commands are aborted.  EH
-         * will be skipped and retrials will be terminated with bad
-         * target.
-         */
-        spin_lock_irqsave(ap->lock, flags);
-        ata_port_freeze(ap);    /* won't be thawed */
-        spin_unlock_irqrestore(ap->lock, flags);
+        /* it better be dead now */
+        WARN_ON(!(ap->pflags & ATA_PFLAG_UNLOADED));
 
-        ata_port_wait_eh(ap);
         cancel_rearming_delayed_work(&ap->hotplug_task);
 
  skip_eh:
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index d673f3712bdc..8147a8386370 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -491,6 +491,31 @@ enum blk_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd)
         return ret;
 }
 
+static void ata_eh_unload(struct ata_port *ap)
+{
+        struct ata_link *link;
+        struct ata_device *dev;
+        unsigned long flags;
+
+        /* Restore SControl IPM and SPD for the next driver and
+         * disable attached devices.
+         */
+        ata_for_each_link(link, ap, PMP_FIRST) {
+                sata_scr_write(link, SCR_CONTROL, link->saved_scontrol & 0xff0);
+                ata_for_each_dev(dev, link, ALL)
+                        ata_dev_disable(dev);
+        }
+
+        /* freeze and set UNLOADED */
+        spin_lock_irqsave(ap->lock, flags);
+
+        ata_port_freeze(ap);                    /* won't be thawed */
+        ap->pflags &= ~ATA_PFLAG_EH_PENDING;    /* clear pending from freeze */
+        ap->pflags |= ATA_PFLAG_UNLOADED;
+
+        spin_unlock_irqrestore(ap->lock, flags);
+}
+
 /**
  *      ata_scsi_error - SCSI layer error handler callback
  *      @host: SCSI host on which error occurred
@@ -618,8 +643,13 @@ void ata_scsi_error(struct Scsi_Host *host)
                 /* invoke EH, skip if unloading or suspended */
                 if (!(ap->pflags & (ATA_PFLAG_UNLOADING | ATA_PFLAG_SUSPENDED)))
                         ap->ops->error_handler(ap);
-                else
+                else {
+                        /* if unloading, commence suicide */
+                        if ((ap->pflags & ATA_PFLAG_UNLOADING) &&
+                            !(ap->pflags & ATA_PFLAG_UNLOADED))
+                                ata_eh_unload(ap);
                         ata_eh_finish(ap);
+                }
 
                 /* process port suspend request */
                 ata_eh_handle_port_suspend(ap);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 3b2a0c6444ee..3449de597eff 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -213,10 +213,11 @@ enum {
         ATA_PFLAG_FROZEN        = (1 << 2), /* port is frozen */
         ATA_PFLAG_RECOVERED     = (1 << 3), /* recovery action performed */
         ATA_PFLAG_LOADING       = (1 << 4), /* boot/loading probe */
-        ATA_PFLAG_UNLOADING     = (1 << 5), /* module is unloading */
         ATA_PFLAG_SCSI_HOTPLUG  = (1 << 6), /* SCSI hotplug scheduled */
         ATA_PFLAG_INITIALIZING  = (1 << 7), /* being initialized, don't touch */
         ATA_PFLAG_RESETTING     = (1 << 8), /* reset in progress */
+        ATA_PFLAG_UNLOADING     = (1 << 9), /* driver is being unloaded */
+        ATA_PFLAG_UNLOADED      = (1 << 10), /* driver is unloaded */
 
         ATA_PFLAG_SUSPENDED     = (1 << 17), /* port is suspended (power) */
         ATA_PFLAG_PM_PENDING    = (1 << 18), /* PM operation pending */