[RFC PATCH 05/10] ftrace: Drop buffer check in function profiler callbacks

[Frederic Weisbecker <fweisbec@gmail.com>]

Drop the null check on hlist->hash. It is wasteful because
we don't register the tracer if the buffer allocation failed,
and the memory barrier in register_ftrace_graph() ensure it
is visible to the callbacks right away.

Also we know the tracing callbacks won't be called after
register_ftrace_graph(), so subsequent buffer resets are safe
too.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
---
 kernel/trace/ftrace.c |    5 -----
 1 files changed, 0 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3cdb35e..dfd8f7c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -384,8 +384,6 @@ function_profile_call(unsigned long ip, unsigned long parent_ip)
 	local_irq_save(flags);
 
 	hlist = &__get_cpu_var(func_hlist_cpu);
-	if (!hlist->hash)
-		goto out;
 
 	rec = function_find_hlist_node(hlist, ip);
 	if (!rec) {
@@ -415,8 +413,6 @@ static void profile_graph_return(struct ftrace_graph_ret *trace)
 
 	local_irq_save(flags);
 	hlist = &__get_cpu_var(func_hlist_cpu);
-	if (!hlist->hash)
-		goto out;
 
 	calltime = trace->rettime - trace->calltime;
 
@@ -439,7 +435,6 @@ static void profile_graph_return(struct ftrace_graph_ret *trace)
 	if (rec)
 		rec->time += calltime;
 
- out:
 	local_irq_restore(flags);
 }
 
-- 
1.6.2.3