linux-kernel - [tip:tracing/ftrace] ftrace: remove struct list_head from struct dyn

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Date:	Fri, 13 Mar 2009 10:39:36 GMT
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	srostedt@...hat.com, tglx@...utronix.de, laijs@...fujitsu.com,
	mingo@...e.hu
Subject: [tip:tracing/ftrace] ftrace: remove struct list_head from struct dyn_ftrace

Commit-ID:  e94142a67f8bad494c593f0a07c9fc2fbec98c0e
Gitweb:     http://git.kernel.org/tip/e94142a67f8bad494c593f0a07c9fc2fbec98c0e
Author:     Lai Jiangshan <laijs@...fujitsu.com>
AuthorDate: Fri, 13 Mar 2009 17:51:27 +0800
Commit:     Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 13 Mar 2009 11:36:20 +0100

ftrace: remove struct list_head from struct dyn_ftrace

Impact: save memory

The struct dyn_ftrace table is very large, this patch will save
about 50%.

Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
Cc: Steven Rostedt <srostedt@...hat.com>
LKML-Reference: <49BA2C9F.8020009@...fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 include/linux/ftrace.h |    1 -
 kernel/trace/ftrace.c  |   14 ++++++++------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index c146c10..9d598bb 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -145,7 +145,6 @@ enum {
 };
 
 struct dyn_ftrace {
-	struct list_head	list;
 	unsigned long		ip; /* address of mcount call-site */
 	unsigned long		flags;
 	struct dyn_arch_ftrace	arch;
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index bf78a4c..90d5729 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -272,7 +272,7 @@ enum {
 
 static int ftrace_filtered;
 
-static LIST_HEAD(ftrace_new_addrs);
+static struct dyn_ftrace *ftrace_new_addrs;
 
 static DEFINE_MUTEX(ftrace_regex_lock);
 
@@ -409,8 +409,8 @@ ftrace_record_ip(unsigned long ip)
 		return NULL;
 
 	rec->ip = ip;
-
-	list_add(&rec->list, &ftrace_new_addrs);
+	rec->flags = (unsigned long)ftrace_new_addrs;
+	ftrace_new_addrs = rec;
 
 	return rec;
 }
@@ -716,19 +716,21 @@ unsigned long		ftrace_update_tot_cnt;
 
 static int ftrace_update_code(struct module *mod)
 {
-	struct dyn_ftrace *p, *t;
+	struct dyn_ftrace *p;
 	cycle_t start, stop;
 
 	start = ftrace_now(raw_smp_processor_id());
 	ftrace_update_cnt = 0;
 
-	list_for_each_entry_safe(p, t, &ftrace_new_addrs, list) {
+	while (ftrace_new_addrs) {
 
 		/* If something went wrong, bail without enabling anything */
 		if (unlikely(ftrace_disabled))
 			return -1;
 
-		list_del_init(&p->list);
+		p = ftrace_new_addrs;
+		ftrace_new_addrs = (struct dyn_ftrace *)p->flags;
+		p->flags = 0L;
 
 		/* convert record (i.e, patch mcount-call with NOP) */
 		if (ftrace_code_disable(mod, p)) {
--
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