[PATCH RFC 2/5] trace: Use regular rcu_dereference_raw API

From: Joel Fernandes (Google)
Date: Fri May 24 2019 - 19:53:05 EST


rcu_dereference_raw already does not do any tracing. There is no need to
use the _notrace variant of it and this series removes that API, so let us
use the regular variant here.

While at it, also replace the only user of
hlist_for_each_entry_rcu_notrace (which indirectly uses the
rcu_dereference_raw_notrace API) with hlist_for_each_entry_rcu which
also does not do any tracing.

Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
kernel/trace/ftrace.c | 4 ++--
kernel/trace/ftrace_internal.h | 8 ++++----
kernel/trace/trace.c | 4 ++--
3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index b920358dd8f7..f7d5f0ee69de 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -706,7 +706,7 @@ ftrace_find_profiled_func(struct ftrace_profile_stat *stat, unsigned long ip)
if (hlist_empty(hhd))
return NULL;

- hlist_for_each_entry_rcu_notrace(rec, hhd, node) {
+ hlist_for_each_entry_rcu(rec, hhd, node) {
if (rec->ip == ip)
return rec;
}
@@ -1135,7 +1135,7 @@ __ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip)
key = ftrace_hash_key(hash, ip);
hhd = &hash->buckets[key];

- hlist_for_each_entry_rcu_notrace(entry, hhd, hlist) {
+ hlist_for_each_entry_rcu(entry, hhd, hlist) {
if (entry->ip == ip)
return entry;
}
diff --git a/kernel/trace/ftrace_internal.h b/kernel/trace/ftrace_internal.h
index 0515a2096f90..e3530a284f46 100644
--- a/kernel/trace/ftrace_internal.h
+++ b/kernel/trace/ftrace_internal.h
@@ -6,22 +6,22 @@

/*
* Traverse the ftrace_global_list, invoking all entries. The reason that we
- * can use rcu_dereference_raw_notrace() is that elements removed from this list
+ * can use rcu_dereference_raw() is that elements removed from this list
* are simply leaked, so there is no need to interact with a grace-period
- * mechanism. The rcu_dereference_raw_notrace() calls are needed to handle
+ * mechanism. The rcu_dereference_raw() calls are needed to handle
* concurrent insertions into the ftrace_global_list.
*
* Silly Alpha and silly pointer-speculation compiler optimizations!
*/
#define do_for_each_ftrace_op(op, list) \
- op = rcu_dereference_raw_notrace(list); \
+ op = rcu_dereference_raw(list); \
do

/*
* Optimized for just a single item in the list (as that is the normal case).
*/
#define while_for_each_ftrace_op(op) \
- while (likely(op = rcu_dereference_raw_notrace((op)->next)) && \
+ while (likely(op = rcu_dereference_raw((op)->next)) && \
unlikely((op) != &ftrace_list_end))

extern struct ftrace_ops __rcu *ftrace_ops_list;
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ec439999f387..cb8d696d9cde 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2638,10 +2638,10 @@ static void ftrace_exports(struct ring_buffer_event *event)

preempt_disable_notrace();

- export = rcu_dereference_raw_notrace(ftrace_exports_list);
+ export = rcu_dereference_raw(ftrace_exports_list);
while (export) {
trace_process_export(export, event);
- export = rcu_dereference_raw_notrace(export->next);
+ export = rcu_dereference_raw(export->next);
}

preempt_enable_notrace();
--
2.22.0.rc1.257.g3120a18244-goog