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Commit 991ec02c authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'tracing-urgent-for-linus' of... 

Merge branch 'tracing-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'tracing-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  function-graph: always initialize task ret_stack
  function-graph: move initialization of new tasks up in fork
  function-graph: add memory barriers for accessing task's ret_stack
  function-graph: enable the stack after initialization of other variables
  function-graph: only allocate init tasks if it was not already done

Manually fix trivial conflict in kernel/trace/ftrace.c
parents 86236611 84047e36

kernel/fork.c

+4 −6
Original line number Diff line number Diff line
@@ -981,6 +981,8 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
	if (!p)

		goto fork_out;



	ftrace_graph_init_task(p);



	rt_mutex_init_task(p);



#ifdef CONFIG_PROVE_LOCKING
@@ -1130,8 +1132,6 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
		}

	}



	ftrace_graph_init_task(p);



	p->pid = pid_nr(pid);

	p->tgid = p->pid;

	if (clone_flags & CLONE_THREAD)
@@ -1140,7 +1140,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
	if (current->nsproxy != p->nsproxy) {

		retval = ns_cgroup_clone(p, pid);

		if (retval)

			goto bad_fork_free_graph;

			goto bad_fork_free_pid;

	}



	p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
@@ -1232,7 +1232,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
		spin_unlock(&current->sighand->siglock);

		write_unlock_irq(&tasklist_lock);

		retval = -ERESTARTNOINTR;

		goto bad_fork_free_graph;

		goto bad_fork_free_pid;

	}



	if (clone_flags & CLONE_THREAD) {
@@ -1267,8 +1267,6 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
	cgroup_post_fork(p);

	return p;



bad_fork_free_graph:

	ftrace_graph_exit_task(p);

bad_fork_free_pid:

	if (pid != &init_struct_pid)

		free_pid(pid);

kernel/trace/ftrace.c

+19 −10
Original line number Diff line number Diff line
@@ -3218,12 +3218,12 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) 
		}



		if (t->ret_stack == NULL) {

			t->curr_ret_stack = -1;

			/* Make sure IRQs see the -1 first: */

			barrier();

			t->ret_stack = ret_stack_list[start++];

			atomic_set(&t->tracing_graph_pause, 0);

			atomic_set(&t->trace_overrun, 0);

			t->curr_ret_stack = -1;

			/* Make sure the tasks see the -1 first: */

			smp_wmb();

			t->ret_stack = ret_stack_list[start++];

		}

	} while_each_thread(g, t);
@@ -3281,8 +3281,10 @@ static int start_graph_tracing(void) 
		return -ENOMEM;



	/* The cpu_boot init_task->ret_stack will never be freed */

	for_each_online_cpu(cpu)

	for_each_online_cpu(cpu) {

		if (!idle_task(cpu)->ret_stack)

			ftrace_graph_init_task(idle_task(cpu));

	}



	do {

		ret = alloc_retstack_tasklist(ret_stack_list);
@@ -3374,18 +3376,25 @@ void unregister_ftrace_graph(void) 
/* Allocate a return stack for newly created task */

void ftrace_graph_init_task(struct task_struct *t)

{

	/* Make sure we do not use the parent ret_stack */

	t->ret_stack = NULL;



	if (ftrace_graph_active) {

		t->ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH

		struct ftrace_ret_stack *ret_stack;



		ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH

				* sizeof(struct ftrace_ret_stack),

				GFP_KERNEL);

		if (!t->ret_stack)

		if (!ret_stack)

			return;

		t->curr_ret_stack = -1;

		atomic_set(&t->tracing_graph_pause, 0);

		atomic_set(&t->trace_overrun, 0);

		t->ftrace_timestamp = 0;

	} else

		t->ret_stack = NULL;

		/* make curr_ret_stack visable before we add the ret_stack */

		smp_wmb();

		t->ret_stack = ret_stack;

	}

}



void ftrace_graph_exit_task(struct task_struct *t)

kernel/trace/trace_functions_graph.c

+6 −0
Original line number Diff line number Diff line
@@ -65,6 +65,12 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth) 
	if (!current->ret_stack)

		return -EBUSY;



	/*

	 * We must make sure the ret_stack is tested before we read

	 * anything else.

	 */

	smp_rmb();



	/* The return trace stack is full */

	if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {

		atomic_inc(&current->trace_overrun);