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Subject[tip:tracing/ftrace] tracing: use union for multi-usages field
Commit-ID:  ee000b7f9fe429d2470c674ccec8d344f6789e0d
Gitweb: http://git.kernel.org/tip/ee000b7f9fe429d2470c674ccec8d344f6789e0d
Author: Lai Jiangshan <laijs@cn.fujitsu.com>
AuthorDate: Tue, 24 Mar 2009 13:38:06 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 24 Mar 2009 16:43:12 +0100

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>


---
include/linux/ftrace.h | 12 +++++++++---
kernel/trace/ftrace.c | 8 ++++----
2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 1141248..015a3d2 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 bb37711..7b8722b 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) */

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