module: Make the mod_tree stuff conditional on PERF_EVENTS || TRACING

Andrew worried about the overhead on small systems; only use the fancy
code when either perf or tracing is enabled.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Requested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 3 insertions, 1 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index ddf35a3368fb..4c1b02e1361d 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -282,7 +282,7 @@ struct module {
          *
          * Cacheline align here, such that:
          *   module_init, module_core, init_size, core_size,
-         *   init_text_size, core_text_size and ltn_core.node[0]
+         *   init_text_size, core_text_size and mtn_core::{mod,node[0]}
          * are on the same cacheline.
          */
         void *module_init       ____cacheline_aligned;
@@ -296,6 +296,7 @@ struct module {
         /* The size of the executable code in each section.  */
         unsigned int init_text_size, core_text_size;
 
+#ifdef CONFIG_MODULES_TREE_LOOKUP
         /*
          * We want mtn_core::{mod,node[0]} to be in the same cacheline as the
          * above entries such that a regular lookup will only touch one
@@ -303,6 +304,7 @@ struct module {
          */
         struct mod_tree_node    mtn_core;
         struct mod_tree_node    mtn_init;
+#endif
 
         /* Size of RO sections of the module (text+rodata) */
         unsigned int init_ro_size, core_ro_size;