X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=wrapper%2Fwriteback.h;h=6601e0f70963b501021b4dbdd9953ed511e0f7e9;hb=2d0428212cbfa3f8428feee160b095f48c2ac974;hp=22b2c1608a5e5df3495fbdcc863859364813cf76;hpb=6284ae7ced3a8c6a4bee55b071d4de74d7400cad;p=lttng-modules.git

diff --git a/wrapper/writeback.h b/wrapper/writeback.h
index 22b2c160..6601e0f7 100644
--- a/wrapper/writeback.h
+++ b/wrapper/writeback.h
@@ -1,7 +1,5 @@
-#ifndef _LTTNG_WRAPPER_WRITEBACK_H
-#define _LTTNG_WRAPPER_WRITEBACK_H
-
-/*
+/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
+ *
  * wrapper/writeback.h
  *
  * wrapper around global_dirty_limit read. Using KALLSYMS with KALLSYMS_ALL
@@ -9,22 +7,11 @@
  * exports this variable to GPL modules.
  *
  * Copyright (C) 2013 Mentor Graphics Corp.
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#ifndef _LTTNG_WRAPPER_WRITEBACK_H
+#define _LTTNG_WRAPPER_WRITEBACK_H
+
 #include <lttng-kernel-version.h>
 
 #ifdef CONFIG_KALLSYMS_ALL
@@ -33,7 +20,7 @@
 
 
 
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(4,2,0)
+#if LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,2,0)
 
 static struct wb_domain *global_wb_domain_sym;
 
@@ -50,7 +37,21 @@ unsigned long wrapper_global_dirty_limit(void)
 		return 0;
 	}
 }
-#else
+
+/*
+ * Canary function to check for 'global_wb_domain' at compile time.
+ *
+ * From 'include/linux/writeback.h':
+ *
+ *   extern struct wb_domain global_wb_domain;
+ */
+static inline
+unsigned long __canary__global_wb_domain(void)
+{
+	return global_wb_domain.dirty_limit;
+}
+
+#elif LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,1,0)
 
 static unsigned long *global_dirty_limit_sym;
 
@@ -67,17 +68,33 @@ unsigned long wrapper_global_dirty_limit(void)
 		return 0;
 	}
 }
+
+/*
+ * Canary function to check for 'global_dirty_limit' at compile time.
+ *
+ * From 'include/linux/writeback.h':
+ *
+ *   extern unsigned long global_dirty_limit;
+ */
+static inline
+unsigned long __canary__global_dirty_limit(void)
+{
+	return global_dirty_limit;
+}
+
 #endif
 
 #else /* CONFIG_KALLSYMS_ALL */
 
 #include <linux/writeback.h>
 
+#if LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,1,0)
 static inline
 unsigned long wrapper_global_dirty_limit(void)
 {
 	return global_dirty_limit;
 }
+#endif
 
 #endif