From b4118ea0f140cae49a94963b566dd17bdad8d9ee Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bart.vanassche@sandisk.com>
Date: Sun, 14 May 2017 03:06:54 +0000
Subject: [PATCH] scst/include/backport.h: Add a kref_read() backport

This patch does not change any functionality.


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@7178 d57e44dd-8a1f-0410-8b47-8ef2f437770f
---
 fcst/ft_sess.c                             | 4 ----
 iscsi-scst/kernel/isert-scst/iser_rdma.c   | 4 ----
 iscsi-scst/kernel/isert-scst/isert_login.c | 4 ----
 scst/include/backport.h                    | 5 +++++
 scst/src/scst_sysfs.c                      | 8 +-------
 5 files changed, 6 insertions(+), 19 deletions(-)

diff --git a/fcst/ft_sess.c b/fcst/ft_sess.c
index c482c74c0..a11507c66 100644
--- a/fcst/ft_sess.c
+++ b/fcst/ft_sess.c
@@ -482,11 +482,7 @@ static void ft_sess_free(struct kref *kref)
 static void ft_sess_put(struct ft_sess *sess)
 {
 	BUG_ON(!sess);
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
 	BUG_ON(kref_read(&sess->kref) <= 0);
-#else
-	BUG_ON(atomic_read(&sess->kref.refcount) <= 0);
-#endif
 	kref_put(&sess->kref, ft_sess_free);
 }
 
diff --git a/iscsi-scst/kernel/isert-scst/iser_rdma.c b/iscsi-scst/kernel/isert-scst/iser_rdma.c
index bfc03f0d9..192494545 100644
--- a/iscsi-scst/kernel/isert-scst/iser_rdma.c
+++ b/iscsi-scst/kernel/isert-scst/iser_rdma.c
@@ -1402,11 +1402,7 @@ static void isert_kref_free(struct kref *kref)
 
 void isert_conn_free(struct isert_connection *isert_conn)
 {
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
 	sBUG_ON(kref_read(&isert_conn->kref) == 0);
-#else
-	sBUG_ON(atomic_read(&isert_conn->kref.refcount) == 0);
-#endif
 	kref_put(&isert_conn->kref, isert_kref_free);
 }
 
diff --git a/iscsi-scst/kernel/isert-scst/isert_login.c b/iscsi-scst/kernel/isert-scst/isert_login.c
index a6ffea6af..6c9e2eac4 100644
--- a/iscsi-scst/kernel/isert-scst/isert_login.c
+++ b/iscsi-scst/kernel/isert-scst/isert_login.c
@@ -113,11 +113,7 @@ static void isert_kref_release_dev(struct kref *kref)
 
 static void isert_dev_release(struct isert_conn_dev *dev)
 {
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
 	sBUG_ON(kref_read(&dev->kref) == 0);
-#else
-	sBUG_ON(atomic_read(&dev->kref.refcount) == 0);
-#endif
 	mutex_lock(&isert_listen_dev.conn_lock);
 	kref_put(&dev->kref, isert_kref_release_dev);
 	mutex_unlock(&isert_listen_dev.conn_lock);
diff --git a/scst/include/backport.h b/scst/include/backport.h
index 29c441981..de3baa95f 100644
--- a/scst/include/backport.h
+++ b/scst/include/backport.h
@@ -361,6 +361,11 @@ static inline int __must_check kref_get_unless_zero(struct kref *kref)
 }
 #endif
 
+/* See also commit 2c935bc57221 */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 11, 0)
+#define kref_read(kref) (atomic_read(&(kref)->refcount))
+#endif
+
 /* <linux/kthread.h> */
 
 /* See also commit 207205a2ba26 */
diff --git a/scst/src/scst_sysfs.c b/scst/src/scst_sysfs.c
index a2a478709..9f3665ac1 100644
--- a/scst/src/scst_sysfs.c
+++ b/scst/src/scst_sysfs.c
@@ -1203,13 +1203,7 @@ void scst_kobject_put_and_wait(struct kobject *kobj, const char *category,
 		goto out_free;
 
 	PRINT_INFO("Waiting for release of sysfs entry for %s %s (%d refs)",
-		   category, name ? : "(?)",
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
-		   kref_read(&kobj->kref)
-#else
-		   atomic_read(&kobj->kref.refcount)
-#endif
-		   );
+		   category, name ? : "(?)", kref_read(&kobj->kref));
 	wait_for_completion(c);
 	PRINT_INFO("Finished waiting for release of %s %s sysfs entry",
 		   category, name ? : "(?)");