[SCSI] Kill the SCSI softirq handling

This patch moves the SCSI softirq handling to the block layer version.
There should be no functional changes.

Signed-off-by: Jens Axboe <axboe@suse.de>

3 files changed, 45 insertions, 101 deletions

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 180676d7115a..ee5f4dfdab14 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -69,7 +69,6 @@
 #include "scsi_logging.h"
 
 static void scsi_done(struct scsi_cmnd *cmd);
-static int scsi_retry_command(struct scsi_cmnd *cmd);
 
 /*
  * Definitions and constants.
@@ -752,7 +751,7 @@ static void scsi_done(struct scsi_cmnd *cmd)
  * isn't running --- used by scsi_times_out */
 void __scsi_done(struct scsi_cmnd *cmd)
 {
-        unsigned long flags;
+        struct request *rq = cmd->request;
 
         /*
          * Set the serial numbers back to zero
@@ -763,71 +762,14 @@ void __scsi_done(struct scsi_cmnd *cmd)
         if (cmd->result)
                 atomic_inc(&cmd->device->ioerr_cnt);
 
+        BUG_ON(!rq);
+
         /*
-         * Next, enqueue the command into the done queue.
-         * It is a per-CPU queue, so we just disable local interrupts
-         * and need no spinlock.
+         * The uptodate/nbytes values don't matter, as we allow partial
+         * completes and thus will check this in the softirq callback
          */
-        local_irq_save(flags);
-        list_add_tail(&cmd->eh_entry, &__get_cpu_var(scsi_done_q));
-        raise_softirq_irqoff(SCSI_SOFTIRQ);
-        local_irq_restore(flags);
-}
-
-/**
- * scsi_softirq - Perform post-interrupt processing of finished SCSI commands.
- *
- * This is the consumer of the done queue.
- *
- * This is called with all interrupts enabled.  This should reduce
- * interrupt latency, stack depth, and reentrancy of the low-level
- * drivers.
- */
-static void scsi_softirq(struct softirq_action *h)
-{
-        int disposition;
-        LIST_HEAD(local_q);
-
-        local_irq_disable();
-        list_splice_init(&__get_cpu_var(scsi_done_q), &local_q);
-        local_irq_enable();
-
-        while (!list_empty(&local_q)) {
-                struct scsi_cmnd *cmd = list_entry(local_q.next,
-                                                   struct scsi_cmnd, eh_entry);
-                /* The longest time any command should be outstanding is the
-                 * per command timeout multiplied by the number of retries.
-                 *
-                 * For a typical command, this is 2.5 minutes */
-                unsigned long wait_for 
-                        = cmd->allowed * cmd->timeout_per_command;
-                list_del_init(&cmd->eh_entry);
-
-                disposition = scsi_decide_disposition(cmd);
-                if (disposition != SUCCESS &&
-                    time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
-                        sdev_printk(KERN_ERR, cmd->device,
-                                    "timing out command, waited %lus\n",
-                                    wait_for/HZ);
-                        disposition = SUCCESS;
-                }
-                        
-                scsi_log_completion(cmd, disposition);
-                switch (disposition) {
-                case SUCCESS:
-                        scsi_finish_command(cmd);
-                        break;
-                case NEEDS_RETRY:
-                        scsi_retry_command(cmd);
-                        break;
-                case ADD_TO_MLQUEUE:
-                        scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
-                        break;
-                default:
-                        if (!scsi_eh_scmd_add(cmd, 0))
-                                scsi_finish_command(cmd);
-                }
-        }
+        rq->completion_data = cmd;
+        blk_complete_request(rq);
 }
 
 /*
@@ -840,7 +782,7 @@ static void scsi_softirq(struct softirq_action *h)
  *              level drivers should not become re-entrant as a result of
  *              this.
  */
-static int scsi_retry_command(struct scsi_cmnd *cmd)
+int scsi_retry_command(struct scsi_cmnd *cmd)
 {
         /*
          * Restore the SCSI command state.
@@ -1273,38 +1215,6 @@ int scsi_device_cancel(struct scsi_device *sdev, int recovery)
 }
 EXPORT_SYMBOL(scsi_device_cancel);
 
-#ifdef CONFIG_HOTPLUG_CPU
-static int scsi_cpu_notify(struct notifier_block *self,
-                           unsigned long action, void *hcpu)
-{
-        int cpu = (unsigned long)hcpu;
-
-        switch(action) {
-        case CPU_DEAD:
-                /* Drain scsi_done_q. */
-                local_irq_disable();
-                list_splice_init(&per_cpu(scsi_done_q, cpu),
-                                 &__get_cpu_var(scsi_done_q));
-                raise_softirq_irqoff(SCSI_SOFTIRQ);
-                local_irq_enable();
-                break;
-        default:
-                break;
-        }
-        return NOTIFY_OK;
-}
-
-static struct notifier_block __devinitdata scsi_cpu_nb = {
-        .notifier_call  = scsi_cpu_notify,
-};
-
-#define register_scsi_cpu() register_cpu_notifier(&scsi_cpu_nb)
-#define unregister_scsi_cpu() unregister_cpu_notifier(&scsi_cpu_nb)
-#else
-#define register_scsi_cpu()
-#define unregister_scsi_cpu()
-#endif /* CONFIG_HOTPLUG_CPU */
-
 MODULE_DESCRIPTION("SCSI core");
 MODULE_LICENSE("GPL");
 
@@ -1338,8 +1248,6 @@ static int __init init_scsi(void)
                 INIT_LIST_HEAD(&per_cpu(scsi_done_q, i));
 
         devfs_mk_dir("scsi");
-        open_softirq(SCSI_SOFTIRQ, scsi_softirq, NULL);
-        register_scsi_cpu();
         printk(KERN_NOTICE "SCSI subsystem initialized\n");
         return 0;
 
@@ -1367,7 +1275,6 @@ static void __exit exit_scsi(void)
         devfs_remove("scsi");
         scsi_exit_procfs();
         scsi_exit_queue();
-        unregister_scsi_cpu();
 }
 
 subsys_initcall(init_scsi);
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index ba93d6e66d48..00c9bf383e23 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1493,6 +1493,41 @@ static void scsi_kill_request(struct request *req, request_queue_t *q)
         __scsi_done(cmd);
 }
 
+static void scsi_softirq_done(struct request *rq)
+{
+        struct scsi_cmnd *cmd = rq->completion_data;
+        unsigned long wait_for = cmd->allowed * cmd->timeout_per_command;
+        int disposition;
+
+        INIT_LIST_HEAD(&cmd->eh_entry);
+
+        disposition = scsi_decide_disposition(cmd);
+        if (disposition != SUCCESS &&
+            time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
+                sdev_printk(KERN_ERR, cmd->device,
+                            "timing out command, waited %lus\n",
+                            wait_for/HZ);
+                disposition = SUCCESS;
+        }
+                        
+        scsi_log_completion(cmd, disposition);
+
+        switch (disposition) {
+                case SUCCESS:
+                        scsi_finish_command(cmd);
+                        break;
+                case NEEDS_RETRY:
+                        scsi_retry_command(cmd);
+                        break;
+                case ADD_TO_MLQUEUE:
+                        scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
+                        break;
+                default:
+                        if (!scsi_eh_scmd_add(cmd, 0))
+                                scsi_finish_command(cmd);
+        }
+}
+
 /*
  * Function:    scsi_request_fn()
  *
@@ -1667,6 +1702,7 @@ struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
         blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
         blk_queue_segment_boundary(q, shost->dma_boundary);
         blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
+        blk_queue_softirq_done(q, scsi_softirq_done);
 
         if (!shost->use_clustering)
                 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index f04e7e11f57a..14a6198cb8d2 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -44,6 +44,7 @@ extern void scsi_init_cmd_from_req(struct scsi_cmnd *cmd,
                 struct scsi_request *sreq);
 extern void __scsi_release_request(struct scsi_request *sreq);
 extern void __scsi_done(struct scsi_cmnd *cmd);
+extern int scsi_retry_command(struct scsi_cmnd *cmd);
 #ifdef CONFIG_SCSI_LOGGING
 void scsi_log_send(struct scsi_cmnd *cmd);
 void scsi_log_completion(struct scsi_cmnd *cmd, int disposition);