[RFC][PATCH v1 1/1] Add WARN_ONCE_RETURN macro

[Andy Shevchenko]

The rationale is to replace the
        if (condition) {
                WARN_ONCE(1, ...);
                return value;
        }
by
        WARN_ONCE_RETURN(condition, value, ...);

Signed-off-by: Andy Shevchenko <andriy.shevche...@linux.intel.com>
---
 include/asm-generic/bug.h  | 17 +++++++++++++++++
 security/smack/smack_lsm.c |  5 +----
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 630dd23..fbf20fd 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -126,6 +126,18 @@ extern void warn_slowpath_null(const char *file, const int 
line);
        unlikely(__ret_warn_once);                              \
 })
 
+#define WARN_ONCE_RETURN(condition, value, format...)          \
+do {                                                           \
+       static bool __section(.data.unlikely) __warned;         \
+       int __ret_warn_once = !!(condition);                    \
+                                                               \
+       if (unlikely(__ret_warn_once)) {                        \
+               if (WARN(!__warned, format))                    \
+                       __warned = true;                        \
+               return value;                                   \
+       }                                                       \
+} while (0)
+
 #define WARN_TAINT_ONCE(condition, taint, format...)   ({      \
        static bool __section(.data.unlikely) __warned;         \
        int __ret_warn_once = !!(condition);                    \
@@ -162,6 +174,11 @@ extern void warn_slowpath_null(const char *file, const int 
line);
 
 #define WARN_ON_ONCE(condition) WARN_ON(condition)
 #define WARN_ONCE(condition, format...) WARN(condition, format)
+#define WARN_ONCE_RETURN(condition, value, format...)                  \
+do {                                                                   \
+       if (WARN(condition, format))                                    \
+               return value;                                           \
+} while (0)
 #define WARN_TAINT(condition, taint, format...) WARN(condition, format)
 #define WARN_TAINT_ONCE(condition, taint, format...) WARN(condition, format)
 
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 54fb3a1..4160d0e 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4401,10 +4401,7 @@ static int smack_audit_rule_match(u32 secid, u32 field, 
u32 op, void *vrule,
        struct smack_known *skp;
        char *rule = vrule;
 
-       if (unlikely(!rule)) {
-               WARN_ONCE(1, "Smack: missing rule\n");
-               return -ENOENT;
-       }
+       WARN_ONCE_RETURN(unlikely(!rule), -ENOENT, "Smack: missing rule\n");
 
        if (field != AUDIT_SUBJ_USER && field != AUDIT_OBJ_USER)
                return 0;
-- 
2.5.0

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