scsi: bsg: Simplify device registration

Use the per-device cdev_device_interface to store the bsg data in the char
device inode, and thus remove the need to embedd the bsg_class_device
structure in the request_queue.

Link: https://lore.kernel.org/r/20210729064845.1044147-2-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

block/bsg-lib.c

@@ -6,6 +6,7 @@
  *  Copyright (C) 2011   Red Hat, Inc.  All rights reserved.
  *  Copyright (C) 2011   Mike Christie
  */
+#include <linux/bsg.h>
 #include <linux/slab.h>
 #include <linux/blk-mq.h>
 #include <linux/delay.h>
@@ -19,6 +20,7 @@
 
 struct bsg_set {
 	struct blk_mq_tag_set	tag_set;
+	struct bsg_device	*bd;
 	bsg_job_fn		*job_fn;
 	bsg_timeout_fn		*timeout_fn;
 };
@@ -327,7 +329,7 @@ void bsg_remove_queue(struct request_queue *q)
 		struct bsg_set *bset =
 			container_of(q->tag_set, struct bsg_set, tag_set);
 
-		bsg_unregister_queue(q);
+		bsg_unregister_queue(bset->bd);
 		blk_cleanup_queue(q);
 		blk_mq_free_tag_set(&bset->tag_set);
 		kfree(bset);
@@ -396,10 +398,9 @@ struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
 	q->queuedata = dev;
 	blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 
-	ret = bsg_register_queue(q, dev, name, &bsg_transport_ops);
-	if (ret) {
-		printk(KERN_ERR "%s: bsg interface failed to "
-		       "initialize - register queue\n", dev->kobj.name);
+	bset->bd = bsg_register_queue(q, dev, name, &bsg_transport_ops);
+	if (IS_ERR(bset->bd)) {
+		ret = PTR_ERR(bset->bd);
 		goto out_cleanup_queue;
 	}
 

drivers/scsi/scsi_bsg.c

@@ -89,7 +89,8 @@ static const struct bsg_ops scsi_bsg_ops = {
 	.free_rq		= scsi_bsg_free_rq,
 };
 
-int scsi_bsg_register_queue(struct request_queue *q, struct device *parent)
+struct bsg_device *scsi_bsg_register_queue(struct scsi_device *sdev)
 {
-	return bsg_register_queue(q, parent, dev_name(parent), &scsi_bsg_ops);
+	return bsg_register_queue(sdev->request_queue, &sdev->sdev_gendev,
+				  dev_name(&sdev->sdev_gendev), &scsi_bsg_ops);
 }

drivers/scsi/scsi_priv.h

@@ -7,6 +7,7 @@
 #include <scsi/scsi_device.h>
 #include <linux/sbitmap.h>
 
+struct bsg_device;
 struct request_queue;
 struct request;
 struct scsi_cmnd;
@@ -180,15 +181,7 @@ static inline void scsi_dh_add_device(struct scsi_device *sdev) { }
 static inline void scsi_dh_release_device(struct scsi_device *sdev) { }
 #endif
 
-#ifdef CONFIG_BLK_DEV_BSG
-int scsi_bsg_register_queue(struct request_queue *q, struct device *parent);
-#else
-static inline int scsi_bsg_register_queue(struct request_queue *q,
-		struct device *parent)
-{
-	return 0;
-}
-#endif
+struct bsg_device *scsi_bsg_register_queue(struct scsi_device *sdev);
 
 extern int scsi_device_max_queue_depth(struct scsi_device *sdev);
 

drivers/scsi/scsi_sysfs.c

@@ -13,6 +13,7 @@
 #include <linux/blkdev.h>
 #include <linux/device.h>
 #include <linux/pm_runtime.h>
+#include <linux/bsg.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_device.h>
@@ -1327,7 +1328,6 @@ static int scsi_target_add(struct scsi_target *starget)
 int scsi_sysfs_add_sdev(struct scsi_device *sdev)
 {
 	int error, i;
-	struct request_queue *rq = sdev->request_queue;
 	struct scsi_target *starget = sdev->sdev_target;
 
 	error = scsi_target_add(starget);
@@ -1366,12 +1366,19 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
 	transport_add_device(&sdev->sdev_gendev);
 	sdev->is_visible = 1;
 
-	error = scsi_bsg_register_queue(rq, &sdev->sdev_gendev);
-	if (error)
-		/* we're treating error on bsg register as non-fatal,
-		 * so pretend nothing went wrong */
+	if (IS_ENABLED(CONFIG_BLK_DEV_BSG)) {
+		sdev->bsg_dev = scsi_bsg_register_queue(sdev);
+		if (IS_ERR(sdev->bsg_dev)) {
+			/*
+			 * We're treating error on bsg register as non-fatal, so
+			 * pretend nothing went wrong.
+			 */
 			sdev_printk(KERN_INFO, sdev,
-			    "Failed to register bsg queue, errno=%d\n", error);
+				    "Failed to register bsg queue, errno=%d\n",
+				    error);
+			sdev->bsg_dev = NULL;
+		}
+	}
 
 	/* add additional host specific attributes */
 	if (sdev->host->hostt->sdev_attrs) {
@@ -1433,7 +1440,8 @@ void __scsi_remove_device(struct scsi_device *sdev)
 			sysfs_remove_groups(&sdev->sdev_gendev.kobj,
 					sdev->host->hostt->sdev_groups);
 
-		bsg_unregister_queue(sdev->request_queue);
+		if (IS_ENABLED(CONFIG_BLK_DEV_BSG) && sdev->bsg_dev)
+			bsg_unregister_queue(sdev->bsg_dev);
 		device_unregister(&sdev->sdev_dev);
 		transport_remove_device(dev);
 		device_del(dev);

include/linux/blkdev.h

@@ -18,7 +18,6 @@
 #include <linux/bio.h>
 #include <linux/stringify.h>
 #include <linux/gfp.h>
-#include <linux/bsg.h>
 #include <linux/smp.h>
 #include <linux/rcupdate.h>
 #include <linux/percpu-refcount.h>
@@ -33,7 +32,6 @@ struct elevator_queue;
 struct blk_trace;
 struct request;
 struct sg_io_hdr;
-struct bsg_job;
 struct blkcg_gq;
 struct blk_flush_queue;
 struct pr_ops;
@@ -535,10 +533,6 @@ struct request_queue {
 
 	int			mq_freeze_depth;
 
-#if IS_ENABLED(CONFIG_BLK_DEV_BSG_COMMON)
-	struct bsg_class_device bsg_dev;
-#endif
-
 #ifdef CONFIG_BLK_DEV_THROTTLING
 	/* Throttle data */
 	struct throtl_data *td;

include/linux/bsg-lib.h

@@ -12,6 +12,7 @@
 #include <linux/blkdev.h>
 #include <scsi/scsi_request.h>
 
+struct bsg_job;
 struct request;
 struct device;
 struct scatterlist;

include/linux/bsg.h

@@ -4,10 +4,11 @@
 
 #include <uapi/linux/bsg.h>
 
+struct bsg_device;
+struct device;
 struct request;
 struct request_queue;
 
-#ifdef CONFIG_BLK_DEV_BSG_COMMON
 struct bsg_ops {
 	int	(*check_proto)(struct sg_io_v4 *hdr);
 	int	(*fill_hdr)(struct request *rq, struct sg_io_v4 *hdr,
@@ -16,19 +17,9 @@ struct bsg_ops {
 	void	(*free_rq)(struct request *rq);
 };
 
-struct bsg_class_device {
-	struct device *class_dev;
-	int minor;
-	struct request_queue *queue;
-	const struct bsg_ops *ops;
-};
+struct bsg_device *bsg_register_queue(struct request_queue *q,
+		struct device *parent, const char *name,
+		const struct bsg_ops *ops);
+void bsg_unregister_queue(struct bsg_device *bcd);
 
-int bsg_register_queue(struct request_queue *q, struct device *parent,
-		const char *name, const struct bsg_ops *ops);
-void bsg_unregister_queue(struct request_queue *q);
-#else
-static inline void bsg_unregister_queue(struct request_queue *q)
-{
-}
-#endif /* CONFIG_BLK_DEV_BSG_COMMON */
 #endif /* _LINUX_BSG_H */

include/scsi/scsi_device.h

@@ -10,6 +10,7 @@
 #include <linux/atomic.h>
 #include <linux/sbitmap.h>
 
+struct bsg_device;
 struct device;
 struct request_queue;
 struct scsi_cmnd;
@@ -235,6 +236,7 @@ struct scsi_device {
 	size_t			dma_drain_len;
 	void			*dma_drain_buf;
 
+	struct bsg_device	*bsg_dev;
 	unsigned char		access_state;
 	struct mutex		state_mutex;
 	enum scsi_device_state sdev_state;