[SCSI] libiscsi: do not take host lock in queuecommand

iscsi_tcp, ib_iser, cxgb*, be2iscsi and bnx2i do not use
the host lock and do not take the session lock against
a irq, so this patch drops the DEF_SCSI_QCMD use. Instead
we just take the session lock and disable bhs.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

2 files changed, 16 insertions, 24 deletions

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 3eddab0774e4..1def8e101249 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -505,6 +505,7 @@ static void iscsi_free_task(struct iscsi_task *task)
         struct iscsi_conn *conn = task->conn;
         struct iscsi_session *session = conn->session;
         struct scsi_cmnd *sc = task->sc;
+        int oldstate = task->state;
 
         ISCSI_DBG_SESSION(session, "freeing task itt 0x%x state %d sc %p\n",
                           task->itt, task->state, task->sc);
@@ -525,10 +526,10 @@ static void iscsi_free_task(struct iscsi_task *task)
                 /* SCSI eh reuses commands to verify us */
                 sc->SCp.ptr = NULL;
                 /*
-                 * queue command may call this to free the task, but
-                 * not have setup the sc callback
+                 * queue command may call this to free the task, so
+                 * it will decide how to return sc to scsi-ml.
                  */
-                if (sc->scsi_done)
+                if (oldstate != ISCSI_TASK_REQUEUE_SCSIQ)
                         sc->scsi_done(sc);
         }
 }
@@ -572,7 +573,8 @@ static void iscsi_complete_task(struct iscsi_task *task, int state)
                           task->itt, task->state, task->sc);
         if (task->state == ISCSI_TASK_COMPLETED ||
             task->state == ISCSI_TASK_ABRT_TMF ||
-            task->state == ISCSI_TASK_ABRT_SESS_RECOV)
+            task->state == ISCSI_TASK_ABRT_SESS_RECOV ||
+            task->state == ISCSI_TASK_REQUEUE_SCSIQ)
                 return;
         WARN_ON_ONCE(task->state == ISCSI_TASK_FREE);
         task->state = state;
@@ -1600,27 +1602,23 @@ enum {
         FAILURE_SESSION_NOT_READY,
 };
 
-static int iscsi_queuecommand_lck(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
+int iscsi_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *sc)
 {
         struct iscsi_cls_session *cls_session;
-        struct Scsi_Host *host;
         struct iscsi_host *ihost;
         int reason = 0;
         struct iscsi_session *session;
         struct iscsi_conn *conn;
         struct iscsi_task *task = NULL;
 
-        sc->scsi_done = done;
         sc->result = 0;
         sc->SCp.ptr = NULL;
 
-        host = sc->device->host;
         ihost = shost_priv(host);
-        spin_unlock(host->host_lock);
 
         cls_session = starget_to_session(scsi_target(sc->device));
         session = cls_session->dd_data;
-        spin_lock(&session->lock);
+        spin_lock_bh(&session->lock);
 
         reason = iscsi_session_chkready(cls_session);
         if (reason) {
@@ -1706,25 +1704,21 @@ static int iscsi_queuecommand_lck(struct scsi_cmnd *sc, void (*done)(struct scsi
         }
 
         session->queued_cmdsn++;
-        spin_unlock(&session->lock);
-        spin_lock(host->host_lock);
+        spin_unlock_bh(&session->lock);
         return 0;
 
 prepd_reject:
-        sc->scsi_done = NULL;
-        iscsi_complete_task(task, ISCSI_TASK_COMPLETED);
+        iscsi_complete_task(task, ISCSI_TASK_REQUEUE_SCSIQ);
 reject:
-        spin_unlock(&session->lock);
+        spin_unlock_bh(&session->lock);
         ISCSI_DBG_SESSION(session, "cmd 0x%x rejected (%d)\n",
                           sc->cmnd[0], reason);
-        spin_lock(host->host_lock);
         return SCSI_MLQUEUE_TARGET_BUSY;
 
 prepd_fault:
-        sc->scsi_done = NULL;
-        iscsi_complete_task(task, ISCSI_TASK_COMPLETED);
+        iscsi_complete_task(task, ISCSI_TASK_REQUEUE_SCSIQ);
 fault:
-        spin_unlock(&session->lock);
+        spin_unlock_bh(&session->lock);
         ISCSI_DBG_SESSION(session, "iscsi: cmd 0x%x is not queued (%d)\n",
                           sc->cmnd[0], reason);
         if (!scsi_bidi_cmnd(sc))
@@ -1733,12 +1727,9 @@ fault:
                 scsi_out(sc)->resid = scsi_out(sc)->length;
                 scsi_in(sc)->resid = scsi_in(sc)->length;
         }
-        done(sc);
-        spin_lock(host->host_lock);
+        sc->scsi_done(sc);
         return 0;
 }
-
-DEF_SCSI_QCMD(iscsi_queuecommand)
 EXPORT_SYMBOL_GPL(iscsi_queuecommand);
 
 int iscsi_change_queue_depth(struct scsi_device *sdev, int depth, int reason)
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index 68e951d79f0b..748382b32b52 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -89,6 +89,7 @@ enum {
         ISCSI_TASK_RUNNING,
         ISCSI_TASK_ABRT_TMF,            /* aborted due to TMF */
         ISCSI_TASK_ABRT_SESS_RECOV,     /* aborted due to session recovery */
+        ISCSI_TASK_REQUEUE_SCSIQ,       /* qcmd requeueing to scsi-ml */
 };
 
 struct iscsi_r2t_info {
@@ -341,7 +342,7 @@ extern int iscsi_eh_abort(struct scsi_cmnd *sc);
 extern int iscsi_eh_recover_target(struct scsi_cmnd *sc);
 extern int iscsi_eh_session_reset(struct scsi_cmnd *sc);
 extern int iscsi_eh_device_reset(struct scsi_cmnd *sc);
-extern int iscsi_queuecommand(struct Scsi_Host *h, struct scsi_cmnd *sc);
+extern int iscsi_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *sc);
 
 /*
  * iSCSI host helpers.