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@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49BA2C9F.8020009@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index c146c10..9d598bb 100644 (file)
--- 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 (file)
--- 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)) {