[libata] Improve timeout handling

On a timeout call a device specific handler early in the recovery so that
we can complete and process successful commands which timed out due to IRQ
loss or the like rather more elegantly.

[Revised to exclude the timeout handling on a few devices that inherit from
 SFF but are not SFF enough to use the default timeout handler]

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 17 insertions, 2 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index ea890911d4fa..01831312c360 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -547,7 +547,7 @@ void ata_scsi_error(struct Scsi_Host *host)
 
         /* For new EH, all qcs are finished in one of three ways -
          * normal completion, error completion, and SCSI timeout.
-         * Both cmpletions can race against SCSI timeout.  When normal
+         * Both completions can race against SCSI timeout.  When normal
          * completion wins, the qc never reaches EH.  When error
          * completion wins, the qc has ATA_QCFLAG_FAILED set.
          *
@@ -562,7 +562,19 @@ void ata_scsi_error(struct Scsi_Host *host)
                 int nr_timedout = 0;
 
                 spin_lock_irqsave(ap->lock, flags);
-
+                
+                /* This must occur under the ap->lock as we don't want
+                   a polled recovery to race the real interrupt handler
+                   
+                   The lost_interrupt handler checks for any completed but
+                   non-notified command and completes much like an IRQ handler.
+                   
+                   We then fall into the error recovery code which will treat
+                   this as if normal completion won the race */
+
+                if (ap->ops->lost_interrupt)
+                        ap->ops->lost_interrupt(ap);
+                        
                 list_for_each_entry_safe(scmd, tmp, &host->eh_cmd_q, eh_entry) {
                         struct ata_queued_cmd *qc;
 
@@ -606,6 +618,9 @@ void ata_scsi_error(struct Scsi_Host *host)
                 ap->eh_tries = ATA_EH_MAX_TRIES;
         } else
                 spin_unlock_wait(ap->lock);
+                
+        /* 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 */