[RFC PATCH 01/13] linux err: Synchronize with Linux 5.10

[Sean Anderson <seanga2@gmail.com>]

This synchronizes linux/err.h with Linux 5.10. Notably, this adds
PTR_ERR_OR_ZERO.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
---

 include/linux/err.h | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/include/linux/err.h b/include/linux/err.h
index 5ede82432d..06a80f9f29 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _LINUX_ERR_H
 #define _LINUX_ERR_H
 
@@ -9,7 +10,7 @@
 
 /*
  * Kernel pointers have redundant information, so we can use a
- * scheme where we can return either an error code or a dentry
+ * scheme where we can return either an error code or a normal
  * pointer with the same return value.
  *
  * This should be a per-architecture thing, to allow different
@@ -21,24 +22,24 @@
 
 #define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
 
-static inline void *ERR_PTR(long error)
+static inline void * __must_check ERR_PTR(long error)
 {
 	return (void *)(CONFIG_ERR_PTR_OFFSET + error);
 }
 
-static inline long PTR_ERR(const void *ptr)
+static inline long __must_check PTR_ERR(__force const void *ptr)
 {
 	return ((long)ptr - CONFIG_ERR_PTR_OFFSET);
 }
 
-static inline long IS_ERR(const void *ptr)
+static inline bool __must_check IS_ERR(__force const void *ptr)
 {
 	return IS_ERR_VALUE((unsigned long)PTR_ERR(ptr));
 }
 
-static inline bool IS_ERR_OR_NULL(const void *ptr)
+static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
 {
-	return !ptr || IS_ERR_VALUE((unsigned long)PTR_ERR(ptr));
+	return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
 }
 
 /**
@@ -54,6 +55,14 @@ static inline void * __must_check ERR_CAST(__force const void *ptr)
 	return (void *) ptr;
 }
 
+static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
+{
+	if (IS_ERR(ptr))
+		return PTR_ERR(ptr);
+	else
+		return 0;
+}
+
 #endif
 
 #endif /* _LINUX_ERR_H */
-- 
2.29.2