7 files changed, 49 insertions, 45 deletions

diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 9d3dcfa79ea2..c05b44b80c23 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -51,8 +51,8 @@
 #include "compat_ptrace.h"
 #endif
 
-DEFINE_TRACE(syscall_enter);
-DEFINE_TRACE(syscall_exit);
+DEFINE_TRACE_FN(syscall_enter, syscall_regfunc, syscall_unregfunc);
+DEFINE_TRACE_FN(syscall_exit, syscall_regfunc, syscall_unregfunc);
 
 enum s390_regset {
         REGSET_GENERAL,
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index a909afef44f4..31e9b97ec4d6 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -37,8 +37,8 @@
 
 #include <trace/syscall.h>
 
-DEFINE_TRACE(syscall_enter);
-DEFINE_TRACE(syscall_exit);
+DEFINE_TRACE_FN(syscall_enter, syscall_regfunc, syscall_unregfunc);
+DEFINE_TRACE_FN(syscall_exit, syscall_regfunc, syscall_unregfunc);
 
 #include "tls.h"
 
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 5984ed04c03b..846a4ae501eb 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -23,6 +23,8 @@ struct tracepoint;
 struct tracepoint {
         const char *name;               /* Tracepoint name */
         int state;                      /* State. */
+        void (*regfunc)(void);
+        void (*unregfunc)(void);
         void **funcs;
 } __attribute__((aligned(32)));         /*
                                          * Aligned on 32 bytes because it is
@@ -60,10 +62,8 @@ struct tracepoint {
  * Make sure the alignment of the structure in the __tracepoints section will
  * not add unwanted padding between the beginning of the section and the
  * structure. Force alignment to the same alignment as the section start.
- * An optional set of (un)registration functions can be passed to perform any
- * additional (un)registration work.
  */
-#define DECLARE_TRACE_WITH_CALLBACK(name, proto, args, reg, unreg)      \
+#define DECLARE_TRACE(name, proto, args)                                \
         extern struct tracepoint __tracepoint_##name;                   \
         static inline void trace_##name(proto)                          \
         {                                                               \
@@ -73,36 +73,23 @@ struct tracepoint {
         }                                                               \
         static inline int register_trace_##name(void (*probe)(proto))   \
         {                                                               \
-                int ret;                                                \
-                void (*func)(void) = reg;                               \
-                                                                        \
-                ret = tracepoint_probe_register(#name, (void *)probe);  \
-                if (func && !ret)                                       \
-                        func();                                         \
-                return ret;                                             \
+                return tracepoint_probe_register(#name, (void *)probe); \
         }                                                               \
         static inline int unregister_trace_##name(void (*probe)(proto)) \
         {                                                               \
-                int ret;                                                \
-                void (*func)(void) = unreg;                             \
-                                                                        \
-                ret = tracepoint_probe_unregister(#name, (void *)probe);\
-                if (func && !ret)                                       \
-                        func();                                         \
-                return ret;                                             \
+                return tracepoint_probe_unregister(#name, (void *)probe);\
         }
 
 
-#define DECLARE_TRACE(name, proto, args)                                 \
-        DECLARE_TRACE_WITH_CALLBACK(name, TP_PROTO(proto), TP_ARGS(args),\
-                                        NULL, NULL);
-
-#define DEFINE_TRACE(name)                                              \
+#define DEFINE_TRACE_FN(name, reg, unreg)                               \
         static const char __tpstrtab_##name[]                           \
         __attribute__((section("__tracepoints_strings"))) = #name;      \
         struct tracepoint __tracepoint_##name                           \
         __attribute__((section("__tracepoints"), aligned(32))) =        \
-                { __tpstrtab_##name, 0, NULL }
+                { __tpstrtab_##name, 0, reg, unreg, NULL }
+
+#define DEFINE_TRACE(name)                                              \
+        DEFINE_TRACE_FN(name, NULL, NULL);
 
 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)                              \
         EXPORT_SYMBOL_GPL(__tracepoint_##name)
@@ -113,7 +100,7 @@ extern void tracepoint_update_probe_range(struct tracepoint *begin,
         struct tracepoint *end);
 
 #else /* !CONFIG_TRACEPOINTS */
-#define DECLARE_TRACE_WITH_CALLBACK(name, proto, args, reg, unreg)      \
+#define DECLARE_TRACE(name, proto, args)                                \
         static inline void _do_trace_##name(struct tracepoint *tp, proto) \
         { }                                                             \
         static inline void trace_##name(proto)                          \
@@ -127,10 +114,7 @@ extern void tracepoint_update_probe_range(struct tracepoint *begin,
                 return -ENOSYS;                                         \
         }
 
-#define DECLARE_TRACE(name, proto, args)                                 \
-        DECLARE_TRACE_WITH_CALLBACK(name, TP_PROTO(proto), TP_ARGS(args),\
-                                        NULL, NULL);
-
+#define DEFINE_TRACE_FN(name, reg, unreg)
 #define DEFINE_TRACE(name)
 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
 #define EXPORT_TRACEPOINT_SYMBOL(name)
@@ -282,10 +266,16 @@ static inline void tracepoint_synchronize_unregister(void)
  * can also by used by generic instrumentation like SystemTap), and
  * it is also used to expose a structured trace record in
  * /sys/kernel/debug/tracing/events/.
+ *
+ * A set of (un)registration functions can be passed to the variant
+ * TRACE_EVENT_FN to perform any (un)registration work.
  */
 
 #define TRACE_EVENT(name, proto, args, struct, assign, print)   \
         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
+#define TRACE_EVENT_FN(name, proto, args, struct,               \
+                assign, print, reg, unreg)                      \
+        DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 #endif
 
 #endif
diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h
index f7a7ae1e8f90..2a969850736d 100644
--- a/include/trace/define_trace.h
+++ b/include/trace/define_trace.h
@@ -26,6 +26,11 @@
 #define TRACE_EVENT(name, proto, args, tstruct, assign, print)  \
         DEFINE_TRACE(name)
 
+#undef TRACE_EVENT_FN
+#define TRACE_EVENT_FN(name, proto, args, tstruct,              \
+                assign, print, reg, unreg)                      \
+        DEFINE_TRACE_FN(name, reg, unreg)
+
 #undef DECLARE_TRACE
 #define DECLARE_TRACE(name, proto, args)        \
         DEFINE_TRACE(name)
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 127400255e4c..3a0b44bdabf7 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -42,6 +42,15 @@
         };                                                      \
         static struct ftrace_event_call event_##name
 
+/* Callbacks are meaningless to ftrace. */
+#undef TRACE_EVENT_FN
+#define TRACE_EVENT_FN(name, proto, args, tstruct,              \
+                assign, print, reg, unreg)                      \
+        TRACE_EVENT(name, TP_PROTO(proto), TP_ARGS(args),       \
+                TP_STRUCT__entry(tstruct),                      \
+                TP_fast_assign(assign),                         \
+                TP_printk(print))
+
 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 
 
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 5dcb7e3a544c..4e1943001854 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -13,18 +13,14 @@
 extern void syscall_regfunc(void);
 extern void syscall_unregfunc(void);
 
-DECLARE_TRACE_WITH_CALLBACK(syscall_enter,
+DECLARE_TRACE(syscall_enter,
         TP_PROTO(struct pt_regs *regs, long id),
-        TP_ARGS(regs, id),
-        syscall_regfunc,
-        syscall_unregfunc
+        TP_ARGS(regs, id)
 );
 
-DECLARE_TRACE_WITH_CALLBACK(syscall_exit,
+DECLARE_TRACE(syscall_exit,
         TP_PROTO(struct pt_regs *regs, long ret),
-        TP_ARGS(regs, ret),
-        syscall_regfunc,
-        syscall_unregfunc
+        TP_ARGS(regs, ret)
 );
 
 #endif
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 9e0a36f0e2a9..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);
 }
@@ -578,7 +586,7 @@ __initcall(init_tracepoints);
 
 #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)
@@ -586,7 +594,6 @@ 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) {
@@ -595,7 +602,6 @@ void syscall_regfunc(void)
                 read_unlock_irqrestore(&tasklist_lock, flags);
         }
         sys_tracepoint_refcount++;
-        mutex_unlock(&regfunc_mutex);
 }
 
 void syscall_unregfunc(void)
@@ -603,7 +609,6 @@ 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);
@@ -612,6 +617,5 @@ void syscall_unregfunc(void)
                 } while_each_thread(g, t);
                 read_unlock_irqrestore(&tasklist_lock, flags);
         }
-        mutex_unlock(&regfunc_mutex);
 }
 #endif