tracing/events: Add module tracepoints

Add trace points to trace module_load, module_free, module_get,
module_put and module_request, and use trace_event facility to
get the trace output.

Here's the sample output:

     TASK-PID    CPU#    TIMESTAMP  FUNCTION
        | |       |          |         |
    <...>-42    [000]     1.758380: module_request: fb0 wait=1 call_site=fb_open
    ...
    <...>-60    [000]     3.269403: module_load: scsi_wait_scan
    <...>-60    [000]     3.269432: module_put: scsi_wait_scan call_site=sys_init_module refcnt=0
    <...>-61    [001]     3.273168: module_free: scsi_wait_scan
    ...
    <...>-1021  [000]    13.836081: module_load: sunrpc
    <...>-1021  [000]    13.840589: module_put: sunrpc call_site=sys_init_module refcnt=-1
    <...>-1027  [000]    13.848098: module_get: sunrpc call_site=try_module_get refcnt=0
    <...>-1027  [000]    13.848308: module_get: sunrpc call_site=get_filesystem refcnt=1
    <...>-1027  [000]    13.848692: module_put: sunrpc call_site=put_filesystem refcnt=0
    ...
 modprobe-2587  [001]  1088.437213: module_load: trace_events_sample F
 modprobe-2587  [001]  1088.437786: module_put: trace_events_sample call_site=sys_init_module refcnt=0

Note:

- the taints flag can be 'F', 'C' and/or 'P' if mod->taints != 0

- the module refcnt is percpu, so it can be negative in a
  specific cpu

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <4A891B3C.5030608@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 11 insertions, 3 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index 098bdb7bfacf..f8f92d015efe 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -17,10 +17,12 @@
 #include <linux/moduleparam.h>
 #include <linux/marker.h>
 #include <linux/tracepoint.h>
-#include <asm/local.h>
 
+#include <asm/local.h>
 #include <asm/module.h>
 
+#include <trace/events/module.h>
+
 /* Not Yet Implemented */
 #define MODULE_SUPPORTED_DEVICE(name)
 
@@ -462,7 +464,10 @@ static inline local_t *__module_ref_addr(struct module *mod, int cpu)
 static inline void __module_get(struct module *module)
 {
         if (module) {
-                local_inc(__module_ref_addr(module, get_cpu()));
+                unsigned int cpu = get_cpu();
+                local_inc(__module_ref_addr(module, cpu));
+                trace_module_get(module, _THIS_IP_,
+                                 local_read(__module_ref_addr(module, cpu)));
                 put_cpu();
         }
 }
@@ -473,8 +478,11 @@ static inline int try_module_get(struct module *module)
 
         if (module) {
                 unsigned int cpu = get_cpu();
-                if (likely(module_is_live(module)))
+                if (likely(module_is_live(module))) {
                         local_inc(__module_ref_addr(module, cpu));
+                        trace_module_get(module, _THIS_IP_,
+                                local_read(__module_ref_addr(module, cpu)));
+                }
                 else
                         ret = 0;
                 put_cpu();