X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Ftracepoint.c;h=cc89be5bc0f8ef3d8776ed0da0cf021cf6a35003;hb=f6325e30ebd6fc870315b017a5d4a6ab15bf790b;hp=070a42bb8920f3922b35822124c09f6b8909e970;hpb=a871bd33a6c0bc86fb47cd02ea2650dd43d3d95f;p=safe%2Fjmp%2Flinux-2.6

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 070a42b..cc89be5 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -48,7 +48,7 @@ static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
 
 /*
  * Note about RCU :
- * It is used to to delay the free of multiple probes array until a quiescent
+ * It is used to delay the free of multiple probes array until a quiescent
  * state is reached.
  * Tracepoint entries modifications are protected by the tracepoints_mutex.
  */
@@ -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);
 }
@@ -555,9 +563,6 @@ int tracepoint_module_notify(struct notifier_block *self,
 
 	switch (val) {
 	case MODULE_STATE_COMING:
-		tracepoint_update_probe_range(mod->tracepoints,
-			mod->tracepoints + mod->num_tracepoints);
-		break;
 	case MODULE_STATE_GOING:
 		tracepoint_update_probe_range(mod->tracepoints,
 			mod->tracepoints + mod->num_tracepoints);
@@ -579,7 +584,9 @@ __initcall(init_tracepoints);
 
 #endif /* CONFIG_MODULES */
 
-static DEFINE_MUTEX(regfunc_mutex);
+#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
+
+/* NB: reg/unreg are called while guarded with the tracepoints_mutex */
 static int sys_tracepoint_refcount;
 
 void syscall_regfunc(void)
@@ -587,16 +594,16 @@ 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);
+			/* Skip kernel threads. */
+			if (t->mm)
+				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)
@@ -604,14 +611,13 @@ 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