scst: Use READ_ONCE() instead of ACCESS_ONCE()

scst/include/backport.h

@@ -69,12 +69,12 @@ static inline unsigned int queue_max_hw_sectors(struct request_queue *q)
 #endif
 #endif
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 26)
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 19, 0) && !defined(READ_ONCE)
 /*
- * See also patch "Move ACCESS_ONCE() to <linux/compiler.h>" (commit ID
- * 9c3cdc1f83a6e07092392ff4aba6466517dbd1d0).
+ * See also patch "kernel: Provide READ_ONCE and ASSIGN_ONCE" (commit ID
+ * 230fa253df6352af12ad0a16128760b5cb3f92df).
  */
-#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
+#define READ_ONCE(x) (*(volatile typeof(x) *)&(x))
 #endif
 
 /* <linux/cpumask.h> */

scst/include/scst.h

@@ -2793,7 +2793,7 @@ struct scst_device {
 	 ** Dev's control mode page related values. Updates serialized
 	 ** by device blocking. Since device blocking protects only
 	 ** commands on the execution stage, in all other read cases
-	 ** use ACCESS_ONCE(), if necessary. Modified independently
+	 ** use READ_ONCE(), if necessary. Modified independently
 	 ** to the above fields, hence the alignment.
 	 *************************************************************/
 

scst/src/dev_handlers/scst_user.c

@@ -3495,7 +3495,7 @@ static int dev_user_register_dev(struct file *file,
 	}
 	/*
 	 * Assumption here is that the private_data reading is atomic,
-	 * hence could be lockless and without ACCESS_ONCE().
+	 * hence could be lockless and without READ_ONCE().
 	 */
 	file->private_data = dev;
 	spin_unlock(&dev_list_lock);

scst/src/dev_handlers/scst_vdisk.c

@@ -148,7 +148,7 @@ struct scst_vdisk_dev {
 
 	/*
 	 * Not protected, because assignments to aligned 64-bit integers are
-	 * atomic. At worst, accesses to it should be covered by ACCESS_ONCE(),
+	 * atomic. At worst, accesses to it should be covered by READ_ONCE(),
 	 * but not sure if that is really needed, so would prefer to keep it
 	 * away from the fast path.
 	 */
@@ -8789,7 +8789,7 @@ static ssize_t vdev_size_show(struct kobject *kobj, struct kobj_attribute *attr,
 
 	dev = container_of(kobj, struct scst_device, dev_kobj);
 	virt_dev = dev->dh_priv;
-	size = ACCESS_ONCE(virt_dev->file_size);
+	size = READ_ONCE(virt_dev->file_size);
 
 	if (virt_dev->nullio && size == VDISK_NULLIO_SIZE)
 		key = false;

scst/src/scst_lib.c

@@ -13525,7 +13525,7 @@ static void scst_process_qerr(struct scst_cmd *cmd)
 
 	/* dev->qerr can be changed behind our back */
 	q = dev->qerr;
-	qerr = ACCESS_ONCE(q); /* ACCESS_ONCE doesn't work for bit fields */
+	qerr = READ_ONCE(q); /* READ_ONCE() doesn't work for bit fields */
 
 	TRACE_DBG("Processing QErr %d for cmd %p", qerr, cmd);
 

scst/src/scst_sysfs.c

@@ -3483,8 +3483,8 @@ static ssize_t scst_dev_block_show(struct kobject *kobj,
 
 	dev = container_of(kobj, struct scst_device, dev_kobj);
 
-	pos = sprintf(buf, "%d %d\n", ACCESS_ONCE(dev->ext_blocks_cnt),
-		dev->ext_blocking_pending);
+	pos = sprintf(buf, "%d %d\n", READ_ONCE(dev->ext_blocks_cnt),
+		      dev->ext_blocking_pending);
 
 	TRACE_EXIT_RES(pos);
 	return pos;

scst/src/scst_targ.c

@@ -3669,7 +3669,7 @@ static inline bool scst_check_alua(struct scst_cmd *cmd, int *out_res)
 	int (*alua_filter)(struct scst_cmd *cmd);
 	bool res = false;
 
-	alua_filter = ACCESS_ONCE(cmd->tgt_dev->alua_filter);
+	alua_filter = READ_ONCE(cmd->tgt_dev->alua_filter);
 	if (unlikely(alua_filter)) {
 		int ac = alua_filter(cmd);
 
@@ -3806,7 +3806,7 @@ static int scst_exec_check_sn(struct scst_cmd **active_cmd)
 
 	EXTRACHECKS_BUG_ON(!cmd->sn_set);
 
-	expected_sn = ACCESS_ONCE(order_data->expected_sn);
+	expected_sn = READ_ONCE(order_data->expected_sn);
 	/* Optimized for lockless fast path */
 	if ((cmd->sn != expected_sn) || (order_data->hq_cmd_count > 0)) {
 		spin_lock_irq(&order_data->sn_lock);