From: Johannes Berg <johannes.berg@xxxxxxxxx>
On old kernels, linux/export.h didn't exist and we need
to include linux/module.h instead. That includes a lot
though and thus defines pr_fmt already. Avoid redefine
warnings by checking if it's defined before and if not
undefining it afterwards.
However, to then avoid issues with kernel.h/printk.h
not defining it again, we need to override there.
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
backport/backport-include/linux/export.h | 7 +++++++
backport/backport-include/linux/kernel.h | 11 +++++++++++
backport/backport-include/linux/printk.h | 9 ++++++---
3 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/backport/backport-include/linux/export.h b/backport/backport-include/linux/export.h
index f7842b7..3686197 100644
--- a/backport/backport-include/linux/export.h
+++ b/backport/backport-include/linux/export.h
@@ -6,7 +6,14 @@
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,2,0))
#include_next <linux/export.h>
#else
+#ifndef pr_fmt
+#define backport_undef_pr_fmt
+#endif
#include <linux/module.h>
+#ifdef backport_undef_pr_fmt
+#undef pr_fmt
+#undef backport_undef_pr_fmt
+#endif
#endif /* (LINUX_VERSION_CODE >= KERNEL_VERSION(3,2,0)) */
#endif /* _COMPAT_LINUX_EXPORT_H */
diff --git a/backport/backport-include/linux/kernel.h b/backport/backport-include/linux/kernel.h
index 24755b0..df344eb 100644
--- a/backport/backport-include/linux/kernel.h
+++ b/backport/backport-include/linux/kernel.h
@@ -242,3 +242,14 @@ int hex_to_bin(char ch);
#endif
#endif /* __BACKPORT_KERNEL_H */
+
+/*
+ * We have to do this outside the include guard, because
+ * out own header (linux/export.h) has to include kernel.h
+ * indirectly (through module.h) and then undef's pr_fmt.
+ * Then, when the real kernel.h gets included again, it's
+ * not defined and we get problems ...
+ */
+#ifndef pr_fmt
+#define pr_fmt(msg) msg
+#endif
diff --git a/backport/backport-include/linux/printk.h b/backport/backport-include/linux/printk.h
index 00d86f3..6bc9931 100644
--- a/backport/backport-include/linux/printk.h
+++ b/backport/backport-include/linux/printk.h
@@ -9,9 +9,7 @@
#include <linux/kernel.h>
#endif /* (LINUX_VERSION_CODE > KERNEL_VERSION(2,6,35)) */
-#ifndef pr_fmt
-#define pr_fmt(fmt) fmt
-#endif
+/* see pr_fmt at end of file */
#if LINUX_VERSION_CODE < KERNEL_VERSION(3,9,0)
/* backports 7a555613 */
@@ -100,3 +98,8 @@ int no_printk(const char *s, ...) { return 0; }
#endif
#endif /* _COMPAT_LINUX_PRINTK_H */
+
+/* This must be outside -- see also kernel.h */
+#ifndef pr_fmt
+#define pr_fmt(fmt) fmt
+#endif
--
1.8.0
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