diff options
| author | Steven Rostedt <srostedt@redhat.com> | 2009-06-02 16:51:55 -0400 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2009-06-02 16:51:55 -0400 |
| commit | 84047e360af0394ac5861d433f26bbcf30f77dd1 (patch) | |
| tree | 55848e2ca4856a64b348a57ecca495c2f065aa0f /kernel/trace | |
| parent | f7e8b616ed1cc6f790b82324bce8a2a60295e5c2 (diff) | |
| download | lwn-84047e360af0394ac5861d433f26bbcf30f77dd1.tar.gz lwn-84047e360af0394ac5861d433f26bbcf30f77dd1.zip | |
function-graph: always initialize task ret_stack
On creating a new task while running the function graph tracer, if
we fail to allocate the ret_stack, and then fail the fork, the
code will free the parent ret_stack. This is because the child
duplicated the parent and currently points to the parent's ret_stack.
This patch always initializes the task's ret_stack to NULL.
[ Impact: prevent crash of parent on low memory during fork ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/ftrace.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 1664d3f33d38..bb081f37cac7 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2738,6 +2738,9 @@ 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 (atomic_read(&ftrace_graph_active)) { struct ftrace_ret_stack *ret_stack; @@ -2753,8 +2756,7 @@ void ftrace_graph_init_task(struct task_struct *t) /* make curr_ret_stack visable before we add the ret_stack */ smp_wmb(); t->ret_stack = ret_stack; - } else - t->ret_stack = NULL; + } } void ftrace_graph_exit_task(struct task_struct *t) |