scsi: core: Fail host creation if creating the proc directory fails

Users expect that the contents of /proc/scsi is in sync with the contents
of /sys/class/scsi_host. Hence fail host creation if creating the proc
directory fails.
Suggested-by: John Garry <john.garry@huawei.com>
Reviewed-by: John Garry <john.garry@huawei.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/20221015002418.30955-4-bvanassche@acm.orgSigned-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/hosts.c

@@ -519,7 +519,8 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 			     "failed to create tmf workq\n");
 		goto fail;
 	}
-	scsi_proc_hostdir_add(shost->hostt);
+	if (scsi_proc_hostdir_add(shost->hostt) < 0)
+		goto fail;
 	return shost;
  fail:
 	/*

drivers/scsi/scsi_priv.h

@@ -111,14 +111,14 @@ extern void scsi_evt_thread(struct work_struct *work);
 
 /* scsi_proc.c */
 #ifdef CONFIG_SCSI_PROC_FS
-extern void scsi_proc_hostdir_add(struct scsi_host_template *);
+extern int scsi_proc_hostdir_add(struct scsi_host_template *);
 extern void scsi_proc_hostdir_rm(struct scsi_host_template *);
 extern void scsi_proc_host_add(struct Scsi_Host *);
 extern void scsi_proc_host_rm(struct Scsi_Host *);
 extern int scsi_init_procfs(void);
 extern void scsi_exit_procfs(void);
 #else
-# define scsi_proc_hostdir_add(sht)	do { } while (0)
+# define scsi_proc_hostdir_add(sht)	0
 # define scsi_proc_hostdir_rm(sht)	do { } while (0)
 # define scsi_proc_host_add(shost)	do { } while (0)
 # define scsi_proc_host_rm(shost)	do { } while (0)

drivers/scsi/scsi_proc.c

@@ -108,20 +108,25 @@ static const struct proc_ops proc_scsi_ops = {
  *
  * Sets sht->proc_dir to the new directory.
  */
-
-void scsi_proc_hostdir_add(struct scsi_host_template *sht)
+int scsi_proc_hostdir_add(struct scsi_host_template *sht)
 {
+	int ret = 0;
+
 	if (!sht->show_info)
-		return;
+		return 0;
 
 	mutex_lock(&global_host_template_mutex);
 	if (!sht->present++) {
 		sht->proc_dir = proc_mkdir(sht->proc_name, proc_scsi);
-        	if (!sht->proc_dir)
+		if (!sht->proc_dir) {
 			printk(KERN_ERR "%s: proc_mkdir failed for %s\n",
 			       __func__, sht->proc_name);
+			ret = -ENOMEM;
+		}
 	}
 	mutex_unlock(&global_host_template_mutex);
+
+	return ret;
 }
 
 /**