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

From: Frederic Weisbecker
Date: Thu Jan 21 2010 - 20:18:44 EST

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

Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
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)

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)

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:


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