Hi Ji, Thank you for the patch! Yet something to improve:
[auto build test ERROR on arm64/for-next/core] [also build test ERROR on v4.16-rc6 next-20180323] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Ji-Zhang/arm64-avoid-race-condition-issue-in-dump_backtrace/20180324-165040 base: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core config: arm64-defconfig (attached as .config) compiler: aarch64-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree make.cross ARCH=arm64 All errors (new ones prefixed by >>): arch/arm64/kernel/traps.c: In function 'dump_backtrace': >> arch/arm64/kernel/traps.c:116:2: error: expected '}' before 'else' else if (tsk->state == TASK_RUNNING) { ^~~~ vim +116 arch/arm64/kernel/traps.c 99 100 void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) 101 { 102 struct stackframe frame; 103 int skip; 104 105 pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk); 106 107 if (!tsk) 108 tsk = current; 109 110 if (!try_get_task_stack(tsk)) 111 return; 112 113 if (tsk == current) { 114 frame.fp = (unsigned long)__builtin_frame_address(0); 115 frame.pc = (unsigned long)dump_backtrace; > 116 else if (tsk->state == TASK_RUNNING) { 117 pr_notice("Do not dump other running tasks\n"); 118 return; 119 } else { 120 /* 121 * task blocked in __switch_to 122 */ 123 frame.fp = thread_saved_fp(tsk); 124 frame.pc = thread_saved_pc(tsk); 125 } 126 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 127 frame.graph = tsk->curr_ret_stack; 128 #endif 129 130 skip = !!regs; 131 printk("Call trace:\n"); 132 do { 133 /* skip until specified stack frame */ 134 if (!skip) { 135 dump_backtrace_entry(frame.pc); 136 } else if (frame.fp == regs->regs[29]) { 137 skip = 0; 138 /* 139 * Mostly, this is the case where this function is 140 * called in panic/abort. As exception handler's 141 * stack frame does not contain the corresponding pc 142 * at which an exception has taken place, use regs->pc 143 * instead. 144 */ 145 dump_backtrace_entry(regs->pc); 146 } 147 } while (!unwind_frame(tsk, &frame)); 148 149 put_task_stack(tsk); 150 } 151 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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