[SCSI] improved eh timeout handler

When a command runs into a timeout we need to send an 'ABORT TASK'
TMF. This is typically done by the 'eh_abort_handler' LLDD callback.

Conceptually, however, this function is a normal SCSI command, so
there is no need to enter the error handler.

This patch implements a new scsi_abort_command() function which
invokes an asynchronous function scsi_eh_abort_handler() to
abort the commands via the usual 'eh_abort_handler'.

If abort succeeds the command is either retried or terminated,
depending on the number of allowed retries. However, 'eh_eflags'
records the abort, so if the retry would fail again the
command is pushed onto the error handler without trying to
abort it (again); it'll be cleared up from SCSI EH.

[hare: smatch detected stray switch fixed]
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

2 files changed, 11 insertions, 0 deletions

diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index de5f5d8f1f8a..91558a1f97f4 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -55,6 +55,7 @@ struct scsi_cmnd {
         struct scsi_device *device;
         struct list_head list;  /* scsi_cmnd participates in queue lists */
         struct list_head eh_entry; /* entry for the host eh_cmd_q */
+        struct delayed_work abort_work;
         int eh_eflags;          /* Used by error handlr */
 
         /*
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index fe3b58e836c8..53075e5039e6 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -479,6 +479,11 @@ struct scsi_host_template {
         unsigned no_write_same:1;
 
         /*
+         * True if asynchronous aborts are not supported
+         */
+        unsigned no_async_abort:1;
+
+        /*
          * Countdown for host blocking with no commands outstanding.
          */
         unsigned int max_host_blocked;
@@ -690,6 +695,11 @@ struct Scsi_Host {
         struct workqueue_struct *work_q;
 
         /*
+         * Task management function work queue
+         */
+        struct workqueue_struct *tmf_work_q;
+
+        /*
          * Host has rejected a command because it was busy.
          */
         unsigned int host_blocked;