Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit be5fc646 authored by Tengfei Fan's avatar Tengfei Fan
Browse files

arm64: break while loop if task had been rescheduled 



While printing a task's backtrace and this task isn't
current task, it is possible that task's fp and fp+8
have the same value, so cannot break the while loop.
This can break while loop if this task had been
rescheduled during print this task's backtrace.

Change-Id: Ibcab9e570946b22869297695216d88368173b62a
Signed-off-by: default avatarTengfei Fan <tengfeif@codeaurora.org>
parent 32aead38

arch/arm64/kernel/traps.c

+23 −0
Original line number Diff line number Diff line
@@ -102,6 +102,9 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) 
{

	struct stackframe frame;

	int skip;

	long cur_state = 0;

	unsigned long cur_sp = 0;

	unsigned long cur_fp = 0;



	pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
@@ -120,6 +123,9 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) 
		 */

		frame.fp = thread_saved_fp(tsk);

		frame.pc = thread_saved_pc(tsk);

		cur_state = tsk->state;

		cur_sp = thread_saved_sp(tsk);

		cur_fp = frame.fp;

	}

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	frame.graph = tsk->curr_ret_stack;
@@ -128,6 +134,23 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) 
	skip = !!regs;

	printk("Call trace:\n");

	do {

		if (tsk != current && (cur_state != tsk->state

			/*

			 * We would not be printing backtrace for the task

			 * that has changed state from uninterruptible to

			 * running before hitting the do-while loop but after

			 * saving the current state. If task is in running

			 * state before saving the state, then we may print

			 * wrong call trace or end up in infinite while loop

			 * if *(fp) and *(fp+8) are same. While the situation

			 * will stop print when that task schedule out.

			 */

			|| cur_sp != thread_saved_sp(tsk)

			|| cur_fp != thread_saved_fp(tsk))) {

			printk("The task:%s had been rescheduled!\n",

				tsk->comm);

			break;

		}

		/* skip until specified stack frame */

		if (!skip) {

			dump_backtrace_entry(frame.pc);