Followup for r1361

git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@1364 d57e44dd-8a1f-0410-8b47-8ef2f437770f

scst/include/scst.h

@@ -1063,7 +1063,10 @@ struct scst_dev_type {
 	/* Optional sysfs attributes */
 	const struct attribute **devt_attrs;
 
-	/* Optional sysfs device attributes */
+	/*
+	 * Optional sysfs device attributes. They are serialized
+	 * by dev_sysfs_mutex.
+	 */
 	const struct attribute **dev_attrs;
 #endif
 
@@ -1145,6 +1148,9 @@ struct scst_tgt {
 	/* Set if tgt_kobj was initialized */
 	unsigned int tgt_kobj_initialized:1;
 
+	/* Set if scst_tgt_sysfs_prepare_put() was called for tgt_kobj */
+	unsigned int tgt_kobj_put_prepared:1;
+
 	/*
 	 * Used to protect sysfs attributes to be called after this
 	 * object was unregistered.
@@ -3218,6 +3224,12 @@ struct scst_trace_log {
 	const char *token;
 };
 
+/*
+ * Main SCST mutex. All targets, devices and dev_types management is done
+ * under this mutex.
+ */
+extern struct mutex scst_mutex;
+
 #ifdef CONFIG_SCST_PROC
 
 /*

scst/src/dev_handlers/scst_vdisk.c

@@ -212,7 +212,8 @@ struct scst_vdisk_dev {
 	int virt_id;
 	char name[16+1];	/* Name of the virtual device,
 				   must be <= SCSI Model + 1 */
-	char *file_name;	/* File name */
+	char *file_name;	/* File name, protected by
+				   scst_mutex and suspended activities */
 	char usn[MAX_USN_LEN];
 	struct scst_device *dev;
 	struct list_head vdisk_dev_list_entry;
@@ -815,7 +816,8 @@ out:
  *
  *  Returns :  None
  *
- *  Description:  Called to detach this device type driver
+ *  Description:  Called to detach this device type driver.
+ *		  Scst_mutex supposed to be held.
  ************************************************************/
 static void vdisk_detach(struct scst_device *dev)
 {
@@ -3457,6 +3459,9 @@ static int vcdrom_change(struct scst_vdisk_dev *virt_dev,
 	if (res != 0)
 		goto out;
 
+	/* To sync with detach*() functions */
+	mutex_lock(&scst_mutex);
+
 	if (*file_name == '\0') {
 		virt_dev->cdrom_empty = 1;
 		TRACE_DBG("%s", "No media");
@@ -3464,7 +3469,7 @@ static int vcdrom_change(struct scst_vdisk_dev *virt_dev,
 		PRINT_ERROR("File path \"%s\" is not "
 			"absolute", file_name);
 		res = -EINVAL;
-		goto out_resume;
+		goto out_unlock;
 	} else
 		virt_dev->cdrom_empty = 0;
 
@@ -3477,7 +3482,7 @@ static int vcdrom_change(struct scst_vdisk_dev *virt_dev,
 			TRACE(TRACE_OUT_OF_MEM, "%s",
 				"Allocation of file_name failed");
 			res = -ENOMEM;
-			goto out_resume;
+			goto out_unlock;
 		}
 
 		strncpy(fn, file_name, len);
@@ -3504,6 +3509,8 @@ static int vcdrom_change(struct scst_vdisk_dev *virt_dev,
 	if (!virt_dev->cdrom_empty)
 		virt_dev->media_changed = 1;
 
+	mutex_unlock(&scst_mutex);
+
 	scst_dev_del_all_thr_data(virt_dev->dev);
 
 	if (!virt_dev->cdrom_empty) {
@@ -3532,6 +3539,9 @@ out:
 out_free:
 	kfree(virt_dev->file_name);
 	virt_dev->file_name = old_fn;
+
+out_unlock:
+	mutex_unlock(&scst_mutex);
 	goto out_resume;
 }
 

scst/src/scst_main.c

@@ -79,6 +79,7 @@
  * flush_scheduled_work().
  */
 struct mutex scst_mutex;
+EXPORT_SYMBOL(scst_mutex);
 
  /* All 3 protected by scst_mutex */
 struct list_head scst_template_list;
@@ -494,6 +495,8 @@ void scst_unregister(struct scst_tgt *tgt)
 
 	TRACE_ENTRY();
 
+	scst_tgt_sysfs_prepare_put(tgt);
+
 	TRACE_DBG("%s", "Calling target driver's release()");
 	tgt->tgtt->release(tgt);
 	TRACE_DBG("%s", "Target driver's release() returned");

scst/src/scst_priv.h

@@ -144,7 +144,6 @@ extern spinlock_t scst_main_lock;
 extern struct scst_sgv_pools scst_sgv;
 
 extern unsigned long scst_flags;
-extern struct mutex scst_mutex;
 extern atomic_t scst_cmd_count;
 extern struct list_head scst_template_list;
 extern struct list_head scst_dev_list;
@@ -443,6 +442,7 @@ static inline int scst_create_tgt_sysfs(struct scst_tgt *tgt)
 {
 	return 0;
 }
+static inline void scst_tgt_sysfs_prepare_put(struct scst_tgt *tgt) { }
 static inline void scst_tgt_sysfs_put(struct scst_tgt *tgt)
 {
 	scst_free_tgt(tgt);
@@ -497,6 +497,7 @@ void scst_sysfs_cleanup(void);
 int scst_create_tgtt_sysfs(struct scst_tgt_template *tgtt);
 void scst_tgtt_sysfs_put(struct scst_tgt_template *tgtt);
 int scst_create_tgt_sysfs(struct scst_tgt *tgt);
+void scst_tgt_sysfs_prepare_put(struct scst_tgt *tgt);
 void scst_tgt_sysfs_put(struct scst_tgt *tgt);
 int scst_create_sess_sysfs(struct scst_session *sess);
 void scst_sess_sysfs_put(struct scst_session *sess);

scst/src/scst_sysfs.c

@@ -484,6 +484,20 @@ out_nomem:
 	goto out;
 }
 
+/*
+ * Must not be called under scst_mutex or there can be a deadlock with
+ * tgt_attr_rwsem
+ */
+void scst_tgt_sysfs_prepare_put(struct scst_tgt *tgt)
+{
+	if (tgt->tgt_kobj_initialized) {
+		down_write(&tgt->tgt_attr_rwsem);
+		tgt->tgt_kobj_put_prepared = 1;
+	}
+
+	return;
+}
+
 /*
  * Must not be called under scst_mutex or there can be a deadlock with
  * tgt_attr_rwsem
@@ -504,7 +518,8 @@ void scst_tgt_sysfs_put(struct scst_tgt *tgt)
 
 		kobject_del(&tgt->tgt_kobj);
 
-		down_write(&tgt->tgt_attr_rwsem);
+		if (!tgt->tgt_kobj_put_prepared)
+			down_write(&tgt->tgt_attr_rwsem);
 		kobject_put(&tgt->tgt_kobj);
 	} else
 		scst_free_tgt(tgt);