qdio: Keep device-specific dbf entries

Keep the per-device dbf entries until module is removed, with
proper error checking for debug feature setup.

Signed-off-by: Stefan Raspl <[e-mail]>
Reviewed-by: Steffen Maier <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

drivers/s390/cio/qdio_debug.c

···
 #include <linux/debugfs.h>
 #include <linux/uaccess.h>
 #include <linux/export.h>
+#include <linux/slab.h>
 #include <asm/debug.h>
 #include "qdio_debug.h"
 #include "qdio.h"
···
 
 static struct dentry *debugfs_root;
 #define QDIO_DEBUGFS_NAME_LEN	10
+#define QDIO_DBF_NAME_LEN	20
 
-void qdio_allocate_dbf(struct qdio_initialize *init_data,
+struct qdio_dbf_entry {
+	char dbf_name[QDIO_DBF_NAME_LEN];
+	debug_info_t *dbf_info;
+	struct list_head dbf_list;
+};
+
+static LIST_HEAD(qdio_dbf_list);
+static DEFINE_MUTEX(qdio_dbf_list_mutex);
+
+static debug_info_t *qdio_get_dbf_entry(char *name)
+{
+	struct qdio_dbf_entry *entry;
+	debug_info_t *rc = NULL;
+
+	mutex_lock(&qdio_dbf_list_mutex);
+	list_for_each_entry(entry, &qdio_dbf_list, dbf_list) {
+		if (strcmp(entry->dbf_name, name) == 0) {
+			rc = entry->dbf_info;
+			break;
+		}
+	}
+	mutex_unlock(&qdio_dbf_list_mutex);
+	return rc;
+}
+
+static void qdio_clear_dbf_list(void)
+{
+	struct qdio_dbf_entry *entry, *tmp;
+
+	mutex_lock(&qdio_dbf_list_mutex);
+	list_for_each_entry_safe(entry, tmp, &qdio_dbf_list, dbf_list) {
+		list_del(&entry->dbf_list);
+		debug_unregister(entry->dbf_info);
+		kfree(entry);
+	}
+	mutex_unlock(&qdio_dbf_list_mutex);
+}
+
+int qdio_allocate_dbf(struct qdio_initialize *init_data,
 		       struct qdio_irq *irq_ptr)
 {
-	char text[20];
+	char text[QDIO_DBF_NAME_LEN];
+	struct qdio_dbf_entry *new_entry;
 
 	DBF_EVENT("qfmt:%1d", init_data->q_format);
 	DBF_HEX(init_data->adapter_name, 8);
···
 	DBF_EVENT("irq:%8lx", (unsigned long)irq_ptr);
 
 	/* allocate trace view for the interface */
-	snprintf(text, 20, "qdio_%s", dev_name(&init_data->cdev->dev));
-	irq_ptr->debug_area = debug_register(text, 2, 1, 16);
-	debug_register_view(irq_ptr->debug_area, &debug_hex_ascii_view);
-	debug_set_level(irq_ptr->debug_area, DBF_WARN);
-	DBF_DEV_EVENT(DBF_ERR, irq_ptr, "dbf created");
+	snprintf(text, QDIO_DBF_NAME_LEN, "qdio_%s",
+					dev_name(&init_data->cdev->dev));
+	irq_ptr->debug_area = qdio_get_dbf_entry(text);
+	if (irq_ptr->debug_area)
+		DBF_DEV_EVENT(DBF_ERR, irq_ptr, "dbf reused");
+	else {
+		irq_ptr->debug_area = debug_register(text, 2, 1, 16);
+		if (!irq_ptr->debug_area)
+			return -ENOMEM;
+		if (debug_register_view(irq_ptr->debug_area,
+						&debug_hex_ascii_view)) {
+			debug_unregister(irq_ptr->debug_area);
+			return -ENOMEM;
+		}
+		debug_set_level(irq_ptr->debug_area, DBF_WARN);
+		DBF_DEV_EVENT(DBF_ERR, irq_ptr, "dbf created");
+		new_entry = kzalloc(sizeof(struct qdio_dbf_entry), GFP_KERNEL);
+		if (!new_entry) {
+			debug_unregister(irq_ptr->debug_area);
+			return -ENOMEM;
+		}
+		strlcpy(new_entry->dbf_name, text, QDIO_DBF_NAME_LEN);
+		new_entry->dbf_info = irq_ptr->debug_area;
+		mutex_lock(&qdio_dbf_list_mutex);
+		list_add(&new_entry->dbf_list, &qdio_dbf_list);
+		mutex_unlock(&qdio_dbf_list_mutex);
+	}
+	return 0;
 }
 
 static int qstat_show(struct seq_file *m, void *v)
···
 
 void qdio_debug_exit(void)
 {
+	qdio_clear_dbf_list();
 	debugfs_remove(debugfs_root);
 	if (qdio_dbf_setup)
 		debug_unregister(qdio_dbf_setup);

drivers/s390/cio/qdio_debug.h

···
 	}
 }
 
-void qdio_allocate_dbf(struct qdio_initialize *init_data,
+int qdio_allocate_dbf(struct qdio_initialize *init_data,
 		       struct qdio_irq *irq_ptr);
 void qdio_setup_debug_entries(struct qdio_irq *irq_ptr,
 			      struct ccw_device *cdev);

drivers/s390/cio/qdio_main.c

···
 		return -ENODEV;
 
 	DBF_EVENT("qfree:%4x", cdev->private->schid.sch_no);
+	DBF_DEV_EVENT(DBF_ERR, irq_ptr, "dbf abandoned");
 	mutex_lock(&irq_ptr->setup_mutex);
 
-	if (irq_ptr->debug_area != NULL) {
-		debug_unregister(irq_ptr->debug_area);
-		irq_ptr->debug_area = NULL;
-	}
+	irq_ptr->debug_area = NULL;
 	cdev->private->qdio_data = NULL;
 	mutex_unlock(&irq_ptr->setup_mutex);
 
···
 		goto out_err;
 
 	mutex_init(&irq_ptr->setup_mutex);
-	qdio_allocate_dbf(init_data, irq_ptr);
+	if (qdio_allocate_dbf(init_data, irq_ptr))
+		goto out_rel;
 
 	/*
 	 * Allocate a page for the chsc calls in qdio_establish.