1 files changed, 105 insertions, 125 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index df4905df5cd4..0ba7a65e7c8d 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -202,24 +202,17 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, bool unbusy)
 	blk_mq_requeue_request(cmd->request, true);
 }
 
-/*
- * Function:    scsi_queue_insert()
- *
- * Purpose:     Insert a command in the midlevel queue.
- *
- * Arguments:   cmd    - command that we are adding to queue.
- *              reason - why we are inserting command to queue.
- *
- * Lock status: Assumed that lock is not held upon entry.
+/**
+ * scsi_queue_insert - Reinsert a command in the queue.
+ * @cmd:    command that we are adding to queue.
+ * @reason: why we are inserting command to queue.
  *
- * Returns:     Nothing.
+ * We do this for one of two cases. Either the host is busy and it cannot accept
+ * any more commands for the time being, or the device returned QUEUE_FULL and
+ * can accept no more commands.
  *
- * Notes:       We do this for one of two cases.  Either the host is busy
- *              and it cannot accept any more commands for the time being,
- *              or the device returned QUEUE_FULL and can accept no more
- *              commands.
- * Notes:       This could be called either from an interrupt context or a
- *              normal process context.
+ * Context: This could be called either from an interrupt context or a normal
+ * process context.
  */
 void scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
 {
@@ -301,16 +294,12 @@ int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 }
 EXPORT_SYMBOL(__scsi_execute);
 
-/*
- * Function:    scsi_init_cmd_errh()
- *
- * Purpose:     Initialize cmd fields related to error handling.
- *
- * Arguments:   cmd	- command that is ready to be queued.
+/**
+ * scsi_init_cmd_errh - Initialize cmd fields related to error handling.
+ * @cmd:  command that is ready to be queued.
  *
- * Notes:       This function has the job of initializing a number of
- *              fields related to error handling.   Typically this will
- *              be called once for each command, as required.
+ * This function has the job of initializing a number of fields related to error
+ * handling. Typically this will be called once for each command, as required.
  */
 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
 {
@@ -496,17 +485,11 @@ static void scsi_starved_list_run(struct Scsi_Host *shost)
 	spin_unlock_irqrestore(shost->host_lock, flags);
 }
 
-/*
- * Function:   scsi_run_queue()
- *
- * Purpose:    Select a proper request queue to serve next
- *
- * Arguments:  q       - last request's queue
- *
- * Returns:     Nothing
+/**
+ * scsi_run_queue - Select a proper request queue to serve next.
+ * @q:  last request's queue
  *
- * Notes:      The previous command was completely finished, start
- *             a new one if possible.
+ * The previous command was completely finished, start a new one if possible.
  */
 static void scsi_run_queue(struct request_queue *q)
 {
@@ -548,7 +531,7 @@ static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
 	}
 }
 
-static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd)
+static void scsi_free_sgtables(struct scsi_cmnd *cmd)
 {
 	if (cmd->sdb.table.nents)
 		sg_free_table_chained(&cmd->sdb.table,
@@ -560,7 +543,7 @@ static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd)
 
 static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
 {
-	scsi_mq_free_sgtables(cmd);
+	scsi_free_sgtables(cmd);
 	scsi_uninit_cmd(cmd);
 }
 
@@ -896,34 +879,27 @@ static int scsi_io_completion_nz_result(struct scsi_cmnd *cmd, int result,
 	return result;
 }
 
-/*
- * Function:    scsi_io_completion()
- *
- * Purpose:     Completion processing for block device I/O requests.
- *
- * Arguments:   cmd   - command that is finished.
- *
- * Lock status: Assumed that no lock is held upon entry.
- *
- * Returns:     Nothing
- *
- * Notes:       We will finish off the specified number of sectors.  If we
- *		are done, the command block will be released and the queue
- *		function will be goosed.  If we are not done then we have to
- *		figure out what to do next:
- *
- *		a) We can call scsi_requeue_command().  The request
- *		   will be unprepared and put back on the queue.  Then
- *		   a new command will be created for it.  This should
- *		   be used if we made forward progress, or if we want
- *		   to switch from READ(10) to READ(6) for example.
- *
- *		b) We can call __scsi_queue_insert().  The request will
- *		   be put back on the queue and retried using the same
- *		   command as before, possibly after a delay.
- *
- *		c) We can call scsi_end_request() with blk_stat other than
- *		   BLK_STS_OK, to fail the remainder of the request.
+/**
+ * scsi_io_completion - Completion processing for SCSI commands.
+ * @cmd:	command that is finished.
+ * @good_bytes:	number of processed bytes.
+ *
+ * We will finish off the specified number of sectors. If we are done, the
+ * command block will be released and the queue function will be goosed. If we
+ * are not done then we have to figure out what to do next:
+ *
+ *   a) We can call scsi_io_completion_reprep().  The request will be
+ *	unprepared and put back on the queue.  Then a new command will
+ *	be created for it.  This should be used if we made forward
+ *	progress, or if we want to switch from READ(10) to READ(6) for
+ *	example.
+ *
+ *   b) We can call scsi_io_completion_action().  The request will be
+ *	put back on the queue and retried using the same command as
+ *	before, possibly after a delay.
+ *
+ *   c) We can call scsi_end_request() with blk_stat other than
+ *	BLK_STS_OK, to fail the remainder of the request.
  */
 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 {
@@ -951,8 +927,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 		blk_rq_sectors(req), good_bytes));
 
 	/*
-	 * Next deal with any sectors which we were able to correctly
-	 * handle. Failed, zero length commands always need to drop down
+	 * Failed, zero length commands always need to drop down
 	 * to retry code. Fast path should return in this block.
 	 */
 	if (likely(blk_rq_bytes(req) > 0 || blk_stat == BLK_STS_OK)) {
@@ -986,16 +961,14 @@ static inline bool scsi_cmd_needs_dma_drain(struct scsi_device *sdev,
 	       sdev->host->hostt->dma_need_drain(rq);
 }
 
-/*
- * Function:    scsi_init_io()
- *
- * Purpose:     SCSI I/O initialize function.
- *
- * Arguments:   cmd   - Command descriptor we wish to initialize
+/**
+ * scsi_init_io - SCSI I/O initialization function.
+ * @cmd:  command descriptor we wish to initialize
  *
- * Returns:     BLK_STS_OK on success
- *		BLK_STS_RESOURCE if the failure is retryable
- *		BLK_STS_IOERR if the failure is fatal
+ * Returns:
+ * * BLK_STS_OK       - on success
+ * * BLK_STS_RESOURCE - if the failure is retryable
+ * * BLK_STS_IOERR    - if the failure is fatal
  */
 blk_status_t scsi_init_io(struct scsi_cmnd *cmd)
 {
@@ -1086,7 +1059,7 @@ blk_status_t scsi_init_io(struct scsi_cmnd *cmd)
 
 	return BLK_STS_OK;
 out_free_sgtables:
-	scsi_mq_free_sgtables(cmd);
+	scsi_free_sgtables(cmd);
 	return ret;
 }
 EXPORT_SYMBOL(scsi_init_io);
@@ -1217,6 +1190,7 @@ static blk_status_t scsi_setup_cmnd(struct scsi_device *sdev,
 		struct request *req)
 {
 	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
+	blk_status_t ret;
 
 	if (!blk_rq_bytes(req))
 		cmd->sc_data_direction = DMA_NONE;
@@ -1226,9 +1200,14 @@ static blk_status_t scsi_setup_cmnd(struct scsi_device *sdev,
 		cmd->sc_data_direction = DMA_FROM_DEVICE;
 
 	if (blk_rq_is_scsi(req))
-		return scsi_setup_scsi_cmnd(sdev, req);
+		ret = scsi_setup_scsi_cmnd(sdev, req);
 	else
-		return scsi_setup_fs_cmnd(sdev, req);
+		ret = scsi_setup_fs_cmnd(sdev, req);
+
+	if (ret != BLK_STS_OK)
+		scsi_free_sgtables(cmd);
+
+	return ret;
 }
 
 static blk_status_t
@@ -1893,6 +1872,7 @@ struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
 int scsi_mq_setup_tags(struct Scsi_Host *shost)
 {
 	unsigned int cmd_size, sgl_size;
+	struct blk_mq_tag_set *tag_set = &shost->tag_set;
 
 	sgl_size = max_t(unsigned int, sizeof(struct scatterlist),
 				scsi_mq_inline_sgl_size(shost));
@@ -1901,21 +1881,21 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
 		cmd_size += sizeof(struct scsi_data_buffer) +
 			sizeof(struct scatterlist) * SCSI_INLINE_PROT_SG_CNT;
 
-	memset(&shost->tag_set, 0, sizeof(shost->tag_set));
+	memset(tag_set, 0, sizeof(*tag_set));
 	if (shost->hostt->commit_rqs)
-		shost->tag_set.ops = &scsi_mq_ops;
+		tag_set->ops = &scsi_mq_ops;
 	else
-		shost->tag_set.ops = &scsi_mq_ops_no_commit;
-	shost->tag_set.nr_hw_queues = shost->nr_hw_queues ? : 1;
-	shost->tag_set.queue_depth = shost->can_queue;
-	shost->tag_set.cmd_size = cmd_size;
-	shost->tag_set.numa_node = NUMA_NO_NODE;
-	shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
-	shost->tag_set.flags |=
+		tag_set->ops = &scsi_mq_ops_no_commit;
+	tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1;
+	tag_set->queue_depth = shost->can_queue;
+	tag_set->cmd_size = cmd_size;
+	tag_set->numa_node = NUMA_NO_NODE;
+	tag_set->flags = BLK_MQ_F_SHOULD_MERGE;
+	tag_set->flags |=
 		BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
-	shost->tag_set.driver_data = shost;
+	tag_set->driver_data = shost;
 
-	return blk_mq_alloc_tag_set(&shost->tag_set);
+	return blk_mq_alloc_tag_set(tag_set);
 }
 
 void scsi_mq_destroy_tags(struct Scsi_Host *shost)
@@ -1944,21 +1924,13 @@ struct scsi_device *scsi_device_from_queue(struct request_queue *q)
 }
 EXPORT_SYMBOL_GPL(scsi_device_from_queue);
 
-/*
- * Function:    scsi_block_requests()
- *
- * Purpose:     Utility function used by low-level drivers to prevent further
- *		commands from being queued to the device.
- *
- * Arguments:   shost       - Host in question
- *
- * Returns:     Nothing
- *
- * Lock status: No locks are assumed held.
+/**
+ * scsi_block_requests - Utility function used by low-level drivers to prevent
+ * further commands from being queued to the device.
+ * @shost:  host in question
  *
- * Notes:       There is no timer nor any other means by which the requests
- *		get unblocked other than the low-level driver calling
- *		scsi_unblock_requests().
+ * There is no timer nor any other means by which the requests get unblocked
+ * other than the low-level driver calling scsi_unblock_requests().
  */
 void scsi_block_requests(struct Scsi_Host *shost)
 {
@@ -1966,25 +1938,15 @@ void scsi_block_requests(struct Scsi_Host *shost)
 }
 EXPORT_SYMBOL(scsi_block_requests);
 
-/*
- * Function:    scsi_unblock_requests()
- *
- * Purpose:     Utility function used by low-level drivers to allow further
- *		commands from being queued to the device.
- *
- * Arguments:   shost       - Host in question
- *
- * Returns:     Nothing
- *
- * Lock status: No locks are assumed held.
- *
- * Notes:       There is no timer nor any other means by which the requests
- *		get unblocked other than the low-level driver calling
- *		scsi_unblock_requests().
- *
- *		This is done as an API function so that changes to the
- *		internals of the scsi mid-layer won't require wholesale
- *		changes to drivers that use this feature.
+/**
+ * scsi_unblock_requests - Utility function used by low-level drivers to allow
+ * further commands to be queued to the device.
+ * @shost:  host in question
+ *
+ * There is no timer nor any other means by which the requests get unblocked
+ * other than the low-level driver calling scsi_unblock_requests(). This is done
+ * as an API function so that changes to the internals of the scsi mid-layer
+ * won't require wholesale changes to drivers that use this feature.
  */
 void scsi_unblock_requests(struct Scsi_Host *shost)
 {
@@ -2865,11 +2827,27 @@ scsi_host_block(struct Scsi_Host *shost)
 	struct scsi_device *sdev;
 	int ret = 0;
 
+	/*
+	 * Call scsi_internal_device_block_nowait so we can avoid
+	 * calling synchronize_rcu() for each LUN.
+	 */
 	shost_for_each_device(sdev, shost) {
-		ret = scsi_internal_device_block(sdev);
+		mutex_lock(&sdev->state_mutex);
+		ret = scsi_internal_device_block_nowait(sdev);
+		mutex_unlock(&sdev->state_mutex);
 		if (ret)
 			break;
 	}
+
+	/*
+	 * SCSI never enables blk-mq's BLK_MQ_F_BLOCKING flag so
+	 * calling synchronize_rcu() once is enough.
+	 */
+	WARN_ON_ONCE(shost->tag_set.flags & BLK_MQ_F_BLOCKING);
+
+	if (!ret)
+		synchronize_rcu();
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(scsi_host_block);
@@ -2882,8 +2860,10 @@ scsi_host_unblock(struct Scsi_Host *shost, int new_state)
 
 	shost_for_each_device(sdev, shost) {
 		ret = scsi_internal_device_unblock(sdev, new_state);
-		if (ret)
+		if (ret) {
+			scsi_device_put(sdev);
 			break;
+		}
 	}
 	return ret;
 }