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SubjectRe: [RFC][PATCH] tracing/module: Move tracepoint out of module.h
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On Thu, 2012-01-26 at 11:28 +0100, Ingo Molnar wrote:

> How much more do we save if we move all of try_module_get() out
> of line? It still seems a rather thick inline function with
> preempt section and all. I'd *really* suggest that it should all
> be uninlined.
>

Here's the #'s

text data bss dec hex filename
7489488 2249584 9719808 19458880 128eb40 vmlinux-prepatch
text data bss dec hex filename
7482458 2248048 9719808 19450314 128c9ca vmlinux-postpatch
text data bss dec hex filename
7477393 2248080 9719808 19445281 128b621 vmlinux-updatedpatch

Thus we get an additional 5k it seems, for a total of 13k savings.

The below patch is what I used. Note, since the tracepoint requires the
instruction pointer, I created stub versions that call a "do_" version
of the function to pass in the local instruction counter.

Rusty, can you give your acked-by on that patch?

Thanks!

-- Steve

diff --git a/include/linux/module.h b/include/linux/module.h
index 3cb7839..2337f97 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -21,8 +21,6 @@
#include <linux/percpu.h>
#include <asm/module.h>

-#include <trace/events/module.h>
-
/* Not Yet Implemented */
#define MODULE_SUPPORTED_DEVICE(name)

@@ -439,34 +437,17 @@ void __symbol_put(const char *symbol);
#define symbol_put(x) __symbol_put(MODULE_SYMBOL_PREFIX #x)
void symbol_put_addr(void *addr);

-/* Sometimes we know we already have a refcount, and it's easier not
- to handle the error case (which only happens with rmmod --wait). */
+extern void do_module_get(struct module *module, int ip);
+extern int do_try_module_get(struct module *module, int ip);
+
static inline void __module_get(struct module *module)
{
- if (module) {
- preempt_disable();
- __this_cpu_inc(module->refptr->incs);
- trace_module_get(module, _THIS_IP_);
- preempt_enable();
- }
+ do_module_get(module, _THIS_IP_);
}

static inline int try_module_get(struct module *module)
{
- int ret = 1;
-
- if (module) {
- preempt_disable();
-
- if (likely(module_is_live(module))) {
- __this_cpu_inc(module->refptr->incs);
- trace_module_get(module, _THIS_IP_);
- } else
- ret = 0;
-
- preempt_enable();
- }
- return ret;
+ return do_try_module_get(module, _THIS_IP_);
}

extern void module_put(struct module *module);
diff --git a/kernel/module.c b/kernel/module.c
index 178333c..8955199 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -928,6 +928,42 @@ void module_put(struct module *module)
}
EXPORT_SYMBOL(module_put);

+static void inc_module(struct module *module, unsigned long ip)
+{
+ __this_cpu_inc(module->refptr->incs);
+ trace_module_get(module, ip);
+}
+
+/* Sometimes we know we already have a refcount, and it's easier not
+ to handle the error case (which only happens with rmmod --wait). */
+void do_module_get(struct module *module, int ip)
+{
+ if (module) {
+ preempt_disable();
+ inc_module(module, ip);
+ preempt_enable();
+ }
+}
+EXPORT_SYMBOL(do_module_get);
+
+int do_try_module_get(struct module *module, int ip)
+{
+ int ret = 1;
+
+ if (module) {
+ preempt_disable();
+
+ if (likely(module_is_live(module)))
+ inc_module(module, ip);
+ else
+ ret = 0;
+
+ preempt_enable();
+ }
+ return ret;
+}
+EXPORT_SYMBOL(do_try_module_get);
+
#else /* !CONFIG_MODULE_UNLOAD */
static inline void print_unload_info(struct seq_file *m, struct module *mod)
{




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