3 files changed, 23 insertions, 18 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 019f380fd764..06be85a7ef8c 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -41,7 +41,7 @@ config HAVE_FTRACE_MCOUNT_RECORD
 config HAVE_HW_BRANCH_TRACER
         bool
 
-config HAVE_FTRACE_SYSCALLS
+config HAVE_SYSCALL_TRACEPOINTS
         bool
 
 config TRACER_MAX_TRACE
@@ -211,7 +211,7 @@ config ENABLE_DEFAULT_TRACERS
 
 config FTRACE_SYSCALLS
         bool "Trace syscalls"
-        depends on HAVE_FTRACE_SYSCALLS
+        depends on HAVE_SYSCALL_TRACEPOINTS
         select GENERIC_TRACER
         select KALLSYMS
         help
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 97a2454760b0..85291c4de406 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -1,4 +1,5 @@
 #include <trace/syscall.h>
+#include <trace/events/syscalls.h>
 #include <linux/kernel.h>
 #include <linux/ftrace.h>
 #include <linux/perf_counter.h>
@@ -288,7 +289,7 @@ int reg_event_syscall_enter(void *ptr)
                 return -ENOSYS;
         mutex_lock(&syscall_trace_lock);
         if (!sys_refcount_enter)
-                ret = register_trace_syscall_enter(ftrace_syscall_enter);
+                ret = register_trace_sys_enter(ftrace_syscall_enter);
         if (ret) {
                 pr_info("event trace: Could not activate"
                                 "syscall entry trace point");
@@ -313,7 +314,7 @@ void unreg_event_syscall_enter(void *ptr)
         sys_refcount_enter--;
         clear_bit(num, enabled_enter_syscalls);
         if (!sys_refcount_enter)
-                unregister_trace_syscall_enter(ftrace_syscall_enter);
+                unregister_trace_sys_enter(ftrace_syscall_enter);
         mutex_unlock(&syscall_trace_lock);
 }
 
@@ -329,7 +330,7 @@ int reg_event_syscall_exit(void *ptr)
                 return -ENOSYS;
         mutex_lock(&syscall_trace_lock);
         if (!sys_refcount_exit)
-                ret = register_trace_syscall_exit(ftrace_syscall_exit);
+                ret = register_trace_sys_exit(ftrace_syscall_exit);
         if (ret) {
                 pr_info("event trace: Could not activate"
                                 "syscall exit trace point");
@@ -354,7 +355,7 @@ void unreg_event_syscall_exit(void *ptr)
         sys_refcount_exit--;
         clear_bit(num, enabled_exit_syscalls);
         if (!sys_refcount_exit)
-                unregister_trace_syscall_exit(ftrace_syscall_exit);
+                unregister_trace_sys_exit(ftrace_syscall_exit);
         mutex_unlock(&syscall_trace_lock);
 }
 
@@ -420,7 +421,7 @@ int reg_prof_syscall_enter(char *name)
 
         mutex_lock(&syscall_trace_lock);
         if (!sys_prof_refcount_enter)
-                ret = register_trace_syscall_enter(prof_syscall_enter);
+                ret = register_trace_sys_enter(prof_syscall_enter);
         if (ret) {
                 pr_info("event trace: Could not activate"
                                 "syscall entry trace point");
@@ -444,7 +445,7 @@ void unreg_prof_syscall_enter(char *name)
         sys_prof_refcount_enter--;
         clear_bit(num, enabled_prof_enter_syscalls);
         if (!sys_prof_refcount_enter)
-                unregister_trace_syscall_enter(prof_syscall_enter);
+                unregister_trace_sys_enter(prof_syscall_enter);
         mutex_unlock(&syscall_trace_lock);
 }
 
@@ -481,7 +482,7 @@ int reg_prof_syscall_exit(char *name)
 
         mutex_lock(&syscall_trace_lock);
         if (!sys_prof_refcount_exit)
-                ret = register_trace_syscall_exit(prof_syscall_exit);
+                ret = register_trace_sys_exit(prof_syscall_exit);
         if (ret) {
                 pr_info("event trace: Could not activate"
                                 "syscall entry trace point");
@@ -505,7 +506,7 @@ void unreg_prof_syscall_exit(char *name)
         sys_prof_refcount_exit--;
         clear_bit(num, enabled_prof_exit_syscalls);
         if (!sys_prof_refcount_exit)
-                unregister_trace_syscall_exit(prof_syscall_exit);
+                unregister_trace_sys_exit(prof_syscall_exit);
         mutex_unlock(&syscall_trace_lock);
 }
 
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 06f165a44083..1a6a453b7efb 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -243,6 +243,11 @@ static void set_tracepoint(struct tracepoint_entry **entry,
 {
         WARN_ON(strcmp((*entry)->name, elem->name) != 0);
 
+        if (elem->regfunc && !elem->state && active)
+                elem->regfunc();
+        else if (elem->unregfunc && elem->state && !active)
+                elem->unregfunc();
+
         /*
          * rcu_assign_pointer has a smp_wmb() which makes sure that the new
          * probe callbacks array is consistent before setting a pointer to it.
@@ -262,6 +267,9 @@ static void set_tracepoint(struct tracepoint_entry **entry,
  */
 static void disable_tracepoint(struct tracepoint *elem)
 {
+        if (elem->unregfunc && elem->state)
+                elem->unregfunc();
+
         elem->state = 0;
         rcu_assign_pointer(elem->funcs, NULL);
 }
@@ -576,9 +584,9 @@ __initcall(init_tracepoints);
 
 #endif /* CONFIG_MODULES */
 
-#ifdef CONFIG_FTRACE_SYSCALLS
+#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
 
-static DEFINE_MUTEX(regfunc_mutex);
+/* NB: reg/unreg are called while guarded with the tracepoints_mutex */
 static int sys_tracepoint_refcount;
 
 void syscall_regfunc(void)
@@ -586,16 +594,14 @@ void syscall_regfunc(void)
         unsigned long flags;
         struct task_struct *g, *t;
 
-        mutex_lock(&regfunc_mutex);
         if (!sys_tracepoint_refcount) {
                 read_lock_irqsave(&tasklist_lock, flags);
                 do_each_thread(g, t) {
-                        set_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);
+                        set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
                 } while_each_thread(g, t);
                 read_unlock_irqrestore(&tasklist_lock, flags);
         }
         sys_tracepoint_refcount++;
-        mutex_unlock(&regfunc_mutex);
 }
 
 void syscall_unregfunc(void)
@@ -603,15 +609,13 @@ void syscall_unregfunc(void)
         unsigned long flags;
         struct task_struct *g, *t;
 
-        mutex_lock(&regfunc_mutex);
         sys_tracepoint_refcount--;
         if (!sys_tracepoint_refcount) {
                 read_lock_irqsave(&tasklist_lock, flags);
                 do_each_thread(g, t) {
-                        clear_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);
+                        clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
                 } while_each_thread(g, t);
                 read_unlock_irqrestore(&tasklist_lock, flags);
         }
-        mutex_unlock(&regfunc_mutex);
 }
 #endif