Kernel起不来出现panic

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wx638ef1cfb1448 2022-12-07 06:59:25 博主文章分类：linux driver ©著作权

文章标签 空指针 3c 2d 文章分类 运维

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转载自展讯FAQ

[QUESTION]
机器起来的时候，死在kernel中，系统起不来。出现panic，有出现如下红色log,其PC指针和LR指针指到了函数：

register_early_suspend，

[    4.641530] c2 PC is at register_early_suspend+0x20/0x88
[    4.646827] c2 LR is at register_early_suspend+0x14/0x88
[    4.652130] c2 pc : [<c00710f4>]    lr : [<c00710e8>]    psr: 00000113
[    4.652130] c2 sp : deca5f18 ip : c0252da4 fp : 00000000
[    4.664122] c2 r10: c0896a54 r9 : 00000000 r8 : c0879d24
[    4.669600] c2 r7 : c0980800 r6 : c089d9a8 r5 : c092094c r4 : c0a573d0
[    4.676380] c2 r3 : 00000000 r2 : 00000033 r1 : 00000000 r0 : c0920964
[    4.683161] c2 Flags: nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel
[    4.690722] c2 Control: 10c53c7d Table: 8000406a DAC: 00000015

[ANSWER]

从堆栈里面看

[ 5.555274] c2 [<c00710f4>] (register_early_suspend+0x20/0x88) from [<c0879d84>] (goodix_ts_init+0x60/0xb0)

[ 5.565002] c2 [<c0879d84>] (goodix_ts_init+0x60/0xb0) from [<c00094fc>] (do_one_initcall+0xcc/0x180)

[ 5.574218] c2 [<c00094fc>] (do_one_initcall+0xcc/0x180) from [<c0851b70>] (kernel_init_freeable+0xf4/0x1c0)

[ 5.584039] c2 [<c0851b70>] (kernel_init_freeable+0xf4/0x1c0) from [<c05c1c1c>] (kernel_init+0x8/0xe4)

[ 5.593338] c2 [<c05c1c1c>] (kernel_init+0x8/0xe4) from [<c000f518>] (ret_from_fork+0x14/0x3c)

从log看问题是register_early_suspend注册所导致，而代码中有goodix_ts_init函数，但去掉这个模块问题还是存在，其实这个问题的本质是register_early_suspend注册的时候出现了空指针所导致，可以在kernel中查找有调用了register_early_suspend的驱动，最终原因是：如下代码红色的部分被注释掉了，就是说register_early_suspend注册完成后就立即kfree释放了，从而导致出现了空指针被使用，导致panic

register_early_suspend(&led->early_suspend);
 #endif led->sprd_torch_close(led);//disabled by default
  
 //return 0;
  
 get_clk_fail:
 config_of_fail:
  kfree(led);
  return ret;