scsi: esas2r: Introduce scsi_template_proc_dir()

Prepare for removing the 'proc_dir' and 'present' members from the SCSI
host template. This commit does not change any functionality.
Reviewed-by: John Garry <john.garry@huawei.com>
Cc: Bradley Grove <linuxdrivers@attotech.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20221015002418.30955-3-bvanassche@acm.orgSigned-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/esas2r/esas2r_main.c

@@ -635,10 +635,13 @@ static void __exit esas2r_exit(void)
 	esas2r_log(ESAS2R_LOG_INFO, "%s called", __func__);
 
 	if (esas2r_proc_major > 0) {
+		struct proc_dir_entry *proc_dir;
+
 		esas2r_log(ESAS2R_LOG_INFO, "unregister proc");
 
-		remove_proc_entry(ATTONODE_NAME,
-				  esas2r_proc_host->hostt->proc_dir);
+		proc_dir = scsi_template_proc_dir(esas2r_proc_host->hostt);
+		if (proc_dir)
+			remove_proc_entry(ATTONODE_NAME, proc_dir);
 		unregister_chrdev(esas2r_proc_major, ESAS2R_DRVR_NAME);
 
 		esas2r_proc_major = 0;
@@ -728,10 +731,12 @@ const char *esas2r_info(struct Scsi_Host *sh)
 			       esas2r_proc_major);
 
 		if (esas2r_proc_major > 0) {
-			struct proc_dir_entry *pde;
+			struct proc_dir_entry *proc_dir;
+			struct proc_dir_entry *pde = NULL;
 
-			pde = proc_create(ATTONODE_NAME, 0,
-					  sh->hostt->proc_dir,
+			proc_dir = scsi_template_proc_dir(sh->hostt);
+			if (proc_dir)
+				pde = proc_create(ATTONODE_NAME, 0, proc_dir,
 						  &esas2r_proc_ops);
 
 			if (!pde) {

drivers/scsi/scsi_proc.c

@@ -83,6 +83,17 @@ static int proc_scsi_host_open(struct inode *inode, struct file *file)
 				4 * PAGE_SIZE);
 }
 
+/**
+ * scsi_template_proc_dir() - returns the procfs dir for a SCSI host template
+ * @sht: SCSI host template pointer.
+ */
+struct proc_dir_entry *
+scsi_template_proc_dir(const struct scsi_host_template *sht)
+{
+	return sht->proc_dir;
+}
+EXPORT_SYMBOL_GPL(scsi_template_proc_dir);
+
 static const struct proc_ops proc_scsi_ops = {
 	.proc_open	= proc_scsi_host_open,
 	.proc_release	= single_release,

include/scsi/scsi_host.h

@@ -751,6 +751,12 @@ extern struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *, int);
 extern int __must_check scsi_add_host_with_dma(struct Scsi_Host *,
 					       struct device *,
 					       struct device *);
+#if defined(CONFIG_SCSI_PROC_FS)
+struct proc_dir_entry *
+scsi_template_proc_dir(const struct scsi_host_template *sht);
+#else
+#define scsi_template_proc_dir(sht) NULL
+#endif
 extern void scsi_scan_host(struct Scsi_Host *);
 extern void scsi_rescan_device(struct device *);
 extern void scsi_remove_host(struct Scsi_Host *);