block: unify request timeout handling

Right now SCSI and others do their own command timeout handling.
Move those bits to the block layer.

Instead of having a timer per command, we try to be a bit more clever
and simply have one per-queue. This avoids the overhead of having to
tear down and setup a timer for each command, so it will result in a lot
less timer fiddling.

Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 17 insertions, 75 deletions

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index ee6be596503d..dbeb86cafc0d 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -291,7 +291,6 @@ struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
                 unsigned long flags;
 
                 cmd->device = dev;
-                init_timer(&cmd->eh_timeout);
                 INIT_LIST_HEAD(&cmd->list);
                 spin_lock_irqsave(&dev->list_lock, flags);
                 list_add_tail(&cmd->list, &dev->cmd_list);
@@ -652,14 +651,19 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
         unsigned long timeout;
         int rtn = 0;
 
+        /*
+         * We will use a queued command if possible, otherwise we will
+         * emulate the queuing and calling of completion function ourselves.
+         */
+        atomic_inc(&cmd->device->iorequest_cnt);
+
         /* check if the device is still usable */
         if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
                 /* in SDEV_DEL we error all commands. DID_NO_CONNECT
                  * returns an immediate error upwards, and signals
                  * that the device is no longer present */
                 cmd->result = DID_NO_CONNECT << 16;
-                atomic_inc(&cmd->device->iorequest_cnt);
-                __scsi_done(cmd);
+                scsi_done(cmd);
                 /* return 0 (because the command has been processed) */
                 goto out;
         }
@@ -672,6 +676,7 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
                  * future requests should not occur until the device 
                  * transitions out of the suspend state.
                  */
+
                 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
 
                 SCSI_LOG_MLQUEUE(3, printk("queuecommand : device blocked \n"));
@@ -714,21 +719,9 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
                 host->resetting = 0;
         }
 
-        /* 
-         * AK: unlikely race here: for some reason the timer could
-         * expire before the serial number is set up below.
-         */
-        scsi_add_timer(cmd, cmd->timeout_per_command, scsi_times_out);
-
         scsi_log_send(cmd);
 
         /*
-         * We will use a queued command if possible, otherwise we will
-         * emulate the queuing and calling of completion function ourselves.
-         */
-        atomic_inc(&cmd->device->iorequest_cnt);
-
-        /*
          * Before we queue this command, check if the command
          * length exceeds what the host adapter can handle.
          */
@@ -744,6 +737,12 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
         }
 
         spin_lock_irqsave(host->host_lock, flags);
+        /*
+         * AK: unlikely race here: for some reason the timer could
+         * expire before the serial number is set up below.
+         *
+         * TODO: kill serial or move to blk layer
+         */
         scsi_cmd_get_serial(host, cmd); 
 
         if (unlikely(host->shost_state == SHOST_DEL)) {
@@ -754,12 +753,8 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
         }
         spin_unlock_irqrestore(host->host_lock, flags);
         if (rtn) {
-                if (scsi_delete_timer(cmd)) {
-                        atomic_inc(&cmd->device->iodone_cnt);
-                        scsi_queue_insert(cmd,
-                                          (rtn == SCSI_MLQUEUE_DEVICE_BUSY) ?
-                                          rtn : SCSI_MLQUEUE_HOST_BUSY);
-                }
+                scsi_queue_insert(cmd, (rtn == SCSI_MLQUEUE_DEVICE_BUSY) ?
+                                                rtn : SCSI_MLQUEUE_HOST_BUSY);
                 SCSI_LOG_MLQUEUE(3,
                     printk("queuecommand : request rejected\n"));
         }
@@ -770,24 +765,6 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
 }
 
 /**
- * scsi_req_abort_cmd -- Request command recovery for the specified command
- * @cmd: pointer to the SCSI command of interest
- *
- * This function requests that SCSI Core start recovery for the
- * command by deleting the timer and adding the command to the eh
- * queue.  It can be called by either LLDDs or SCSI Core.  LLDDs who
- * implement their own error recovery MAY ignore the timeout event if
- * they generated scsi_req_abort_cmd.
- */
-void scsi_req_abort_cmd(struct scsi_cmnd *cmd)
-{
-        if (!scsi_delete_timer(cmd))
-                return;
-        scsi_times_out(cmd);
-}
-EXPORT_SYMBOL(scsi_req_abort_cmd);
-
-/**
  * scsi_done - Enqueue the finished SCSI command into the done queue.
  * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
  * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
@@ -802,42 +779,7 @@ EXPORT_SYMBOL(scsi_req_abort_cmd);
  */
 static void scsi_done(struct scsi_cmnd *cmd)
 {
-        /*
-         * We don't have to worry about this one timing out anymore.
-         * If we are unable to remove the timer, then the command
-         * has already timed out.  In which case, we have no choice but to
-         * let the timeout function run, as we have no idea where in fact
-         * that function could really be.  It might be on another processor,
-         * etc, etc.
-         */
-        if (!scsi_delete_timer(cmd))
-                return;
-        __scsi_done(cmd);
-}
-
-/* Private entry to scsi_done() to complete a command when the timer
- * isn't running --- used by scsi_times_out */
-void __scsi_done(struct scsi_cmnd *cmd)
-{
-        struct request *rq = cmd->request;
-
-        /*
-         * Set the serial numbers back to zero
-         */
-        cmd->serial_number = 0;
-
-        atomic_inc(&cmd->device->iodone_cnt);
-        if (cmd->result)
-                atomic_inc(&cmd->device->ioerr_cnt);
-
-        BUG_ON(!rq);
-
-        /*
-         * The uptodate/nbytes values don't matter, as we allow partial
-         * completes and thus will check this in the softirq callback
-         */
-        rq->completion_data = cmd;
-        blk_complete_request(rq);
+        blk_complete_request(cmd->request);
 }
 
 /* Move this to a header if it becomes more generally useful */