1 files changed, 43 insertions, 1 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 6780f4d16e81..5e590504f3aa 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -463,6 +463,41 @@ static void ata_eh_clear_action(struct ata_link *link, struct ata_device *dev,
 }
 
 /**
+ *      ata_eh_acquire - acquire EH ownership
+ *      @ap: ATA port to acquire EH ownership for
+ *
+ *      Acquire EH ownership for @ap.  This is the basic exclusion
+ *      mechanism for ports sharing a host.  Only one port hanging off
+ *      the same host can claim the ownership of EH.
+ *
+ *      LOCKING:
+ *      EH context.
+ */
+void ata_eh_acquire(struct ata_port *ap)
+{
+        mutex_lock(&ap->host->eh_mutex);
+        WARN_ON_ONCE(ap->host->eh_owner);
+        ap->host->eh_owner = current;
+}
+
+/**
+ *      ata_eh_release - release EH ownership
+ *      @ap: ATA port to release EH ownership for
+ *
+ *      Release EH ownership for @ap if the caller.  The caller must
+ *      have acquired EH ownership using ata_eh_acquire() previously.
+ *
+ *      LOCKING:
+ *      EH context.
+ */
+void ata_eh_release(struct ata_port *ap)
+{
+        WARN_ON_ONCE(ap->host->eh_owner != current);
+        ap->host->eh_owner = NULL;
+        mutex_unlock(&ap->host->eh_mutex);
+}
+
+/**
  *      ata_scsi_timed_out - SCSI layer time out callback
  *      @cmd: timed out SCSI command
  *
@@ -639,11 +674,13 @@ void ata_scsi_error(struct Scsi_Host *host)
         /* If we timed raced normal completion and there is nothing to
            recover nr_timedout == 0 why exactly are we doing error recovery ? */
 
- repeat:
         /* invoke error handler */
         if (ap->ops->error_handler) {
                 struct ata_link *link;
 
+                /* acquire EH ownership */
+                ata_eh_acquire(ap);
+ repeat:
                 /* kill fast drain timer */
                 del_timer_sync(&ap->fastdrain_timer);
 
@@ -718,6 +755,7 @@ void ata_scsi_error(struct Scsi_Host *host)
                 host->host_eh_scheduled = 0;
 
                 spin_unlock_irqrestore(ap->lock, flags);
+                ata_eh_release(ap);
         } else {
                 WARN_ON(ata_qc_from_tag(ap, ap->link.active_tag) == NULL);
                 ap->ops->eng_timeout(ap);
@@ -2818,8 +2856,10 @@ int ata_eh_reset(struct ata_link *link, int classify,
                         "reset failed (errno=%d), retrying in %u secs\n",
                         rc, DIV_ROUND_UP(jiffies_to_msecs(delta), 1000));
 
+                ata_eh_release(ap);
                 while (delta)
                         delta = schedule_timeout_uninterruptible(delta);
+                ata_eh_acquire(ap);
         }
 
         if (try == max_tries - 1) {
@@ -3635,8 +3675,10 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
                 if (time_before_eq(deadline, now))
                         break;
 
+                ata_eh_release(ap);
                 deadline = wait_for_completion_timeout(&ap->park_req_pending,
                                                        deadline - now);
+                ata_eh_acquire(ap);
         } while (deadline);
         ata_for_each_link(link, ap, EDGE) {
                 ata_for_each_dev(dev, link, ALL) {