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
......@@ -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);
......
......@@ -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)
ftrace_graph_init_task(idle_task(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)
......
......@@ -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);
......
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