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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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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
This commit is contained in:
commit
991ec02cdc
3 changed files with 29 additions and 16 deletions
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@ -981,6 +981,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
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if (!p)
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goto fork_out;
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ftrace_graph_init_task(p);
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rt_mutex_init_task(p);
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#ifdef CONFIG_PROVE_LOCKING
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@ -1130,8 +1132,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
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}
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}
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ftrace_graph_init_task(p);
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p->pid = pid_nr(pid);
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p->tgid = p->pid;
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if (clone_flags & CLONE_THREAD)
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@ -1140,7 +1140,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
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if (current->nsproxy != p->nsproxy) {
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retval = ns_cgroup_clone(p, pid);
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if (retval)
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goto bad_fork_free_graph;
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goto bad_fork_free_pid;
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}
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p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
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@ -1232,7 +1232,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
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spin_unlock(¤t->sighand->siglock);
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write_unlock_irq(&tasklist_lock);
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retval = -ERESTARTNOINTR;
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goto bad_fork_free_graph;
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goto bad_fork_free_pid;
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}
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if (clone_flags & CLONE_THREAD) {
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@ -1267,8 +1267,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
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cgroup_post_fork(p);
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return p;
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bad_fork_free_graph:
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ftrace_graph_exit_task(p);
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bad_fork_free_pid:
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if (pid != &init_struct_pid)
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free_pid(pid);
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@ -3218,12 +3218,12 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list)
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}
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if (t->ret_stack == NULL) {
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t->curr_ret_stack = -1;
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/* Make sure IRQs see the -1 first: */
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barrier();
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t->ret_stack = ret_stack_list[start++];
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atomic_set(&t->tracing_graph_pause, 0);
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atomic_set(&t->trace_overrun, 0);
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t->curr_ret_stack = -1;
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/* Make sure the tasks see the -1 first: */
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smp_wmb();
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t->ret_stack = ret_stack_list[start++];
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}
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} while_each_thread(g, t);
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@ -3281,8 +3281,10 @@ static int start_graph_tracing(void)
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return -ENOMEM;
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/* The cpu_boot init_task->ret_stack will never be freed */
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for_each_online_cpu(cpu)
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ftrace_graph_init_task(idle_task(cpu));
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for_each_online_cpu(cpu) {
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if (!idle_task(cpu)->ret_stack)
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ftrace_graph_init_task(idle_task(cpu));
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}
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do {
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ret = alloc_retstack_tasklist(ret_stack_list);
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@ -3374,18 +3376,25 @@ void unregister_ftrace_graph(void)
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/* Allocate a return stack for newly created task */
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void ftrace_graph_init_task(struct task_struct *t)
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{
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/* Make sure we do not use the parent ret_stack */
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t->ret_stack = NULL;
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if (ftrace_graph_active) {
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t->ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
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struct ftrace_ret_stack *ret_stack;
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ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
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* sizeof(struct ftrace_ret_stack),
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GFP_KERNEL);
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if (!t->ret_stack)
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if (!ret_stack)
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return;
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t->curr_ret_stack = -1;
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atomic_set(&t->tracing_graph_pause, 0);
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atomic_set(&t->trace_overrun, 0);
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t->ftrace_timestamp = 0;
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} else
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t->ret_stack = NULL;
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/* make curr_ret_stack visable before we add the ret_stack */
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smp_wmb();
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t->ret_stack = ret_stack;
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}
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}
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void ftrace_graph_exit_task(struct task_struct *t)
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@ -65,6 +65,12 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth)
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if (!current->ret_stack)
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return -EBUSY;
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/*
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* We must make sure the ret_stack is tested before we read
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* anything else.
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*/
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smp_rmb();
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/* The return trace stack is full */
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if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
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atomic_inc(¤t->trace_overrun);
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