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authorLinus Torvalds <torvalds@linux-foundation.org>2009-06-10 19:58:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-10 19:58:10 -0700
commit991ec02cdca33b03a132a0cacfe6f0aa0be9aa8d (patch)
tree50b5f4e2b9f138da57f76eca44fdcc80a2fcd428 /kernel
parent862366118026a358882eefc70238dbcc3db37aac (diff)
parent84047e360af0394ac5861d433f26bbcf30f77dd1 (diff)
downloadlinux-2.6.34-ux500-991ec02cdca33b03a132a0cacfe6f0aa0be9aa8d.tar.gz
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
Diffstat (limited to 'kernel')
-rw-r--r--kernel/fork.c10
-rw-r--r--kernel/trace/ftrace.c29
-rw-r--r--kernel/trace/trace_functions_graph.c6
3 files changed, 29 insertions, 16 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 5449efbc642..bb762b4dd21 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -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);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d6973dfadb3..bb60732ade0 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -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)
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 10f6ad7d85f..8b592418d8b 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -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);