tracing: use union for multi-usages field

Impact: cleanup

struct dyn_ftrace::ip has different usages in his lifecycle,
we use union for it. And also for struct dyn_ftrace::flags.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49C871BE.3080405@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 13 insertions, 7 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 1141248c84ee..015a3d22cf74 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -145,9 +145,15 @@ enum {
 };
 
 struct dyn_ftrace {
-        unsigned long           ip; /* address of mcount call-site */
-        unsigned long           flags;
-        struct dyn_arch_ftrace  arch;
+        union {
+                unsigned long           ip; /* address of mcount call-site */
+                struct dyn_ftrace       *freelist;
+        };
+        union {
+                unsigned long           flags;
+                struct dyn_ftrace       *newlist;
+        };
+        struct dyn_arch_ftrace          arch;
 };
 
 int ftrace_force_update(void);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index bb377112b1bb..7b8722baf153 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -341,7 +341,7 @@ static inline int record_frozen(struct dyn_ftrace *rec)
 
 static void ftrace_free_rec(struct dyn_ftrace *rec)
 {
-        rec->ip = (unsigned long)ftrace_free_records;
+        rec->freelist = ftrace_free_records;
         ftrace_free_records = rec;
         rec->flags |= FTRACE_FL_FREE;
 }
@@ -379,7 +379,7 @@ static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
                         return NULL;
                 }
 
-                ftrace_free_records = (void *)rec->ip;
+                ftrace_free_records = rec->freelist;
                 memset(rec, 0, sizeof(*rec));
                 return rec;
         }
@@ -411,7 +411,7 @@ ftrace_record_ip(unsigned long ip)
                 return NULL;
 
         rec->ip = ip;
-        rec->flags = (unsigned long)ftrace_new_addrs;
+        rec->newlist = ftrace_new_addrs;
         ftrace_new_addrs = rec;
 
         return rec;
@@ -731,7 +731,7 @@ static int ftrace_update_code(struct module *mod)
                         return -1;
 
                 p = ftrace_new_addrs;
-                ftrace_new_addrs = (struct dyn_ftrace *)p->flags;
+                ftrace_new_addrs = p->newlist;
                 p->flags = 0L;
 
                 /* convert record (i.e, patch mcount-call with NOP) */