Re: rwl manipulation fails when

Is your thread a realtime thread? You can't use the lock unless your thread
is realtime (not necessarily hard realtime). You would rt_task_init*
functions are your friends.

On Thu, Dec 1, 2016 at 3:29 AM, Yamato Kira <[email protected]> wrote:

> Hi, everyone
>
>
> I am trying to use the RWL to achieve a synchronization of data processing
> on LinuxCNC which has an RTAI core of 3.9.
>
>
> The RWL I used can be initialized correctly in a thread, but it caused a
> kernel error when I try to lock it or unlock it. Have you ever meet this
> problem before? Or can you help me to fix it? 3Q~
>
>
> The RWL codes I used read as:
>
>
> **************************************************
>
> RWL * rt_RWL_01;
>
> ......
>
> rt_RWL_01 = rt_rwl_init(nam2num("RWL1"));
>     if(0==rt_RWL_01){
>         printf("RWL Init Fails %d\n",rt_RWL_01);
>     }else{
>         printf("RWL Init Succeeds %d\n",rt_RWL_01);
>     }
> ......
> while(1){
> ......
>         printf("Before RWL\n");
>         rt_rwl_wrlock(rt_RWL_01);
>         //rt_rwl_unlock(rt_RWL_01);
>         printf("After RWL\n");
> }
> **************************************************
>
> and the dmesg command gives:
>
> kern  :alert : [ 2855.372788] BUG: unable to handle kernel NULL pointer
> dereference at 0000007c
> kern  :alert : [ 2855.372793] IP: [<f86f2760>] rt_rwl_wrlock+0x30/0x200
> [rtai_sched]
> kern  :warn  : [ 2855.372798] *pde = 00000000
> kern  :warn  : [ 2855.372801] Oops: 0000 [#2] PREEMPT SMP
> kern  :warn  : [ 2855.372804] Modules linked in: rtai_sched(O) rtai_hal(O)
> parport_pc ppdev lp parport rfcomm bnep uinput nfsd nfs nfs_acl auth_rpcgss
> fscache lockd sunrpc loop snd_hda_codec_realtek btusb bluetooth uvcvideo
> snd_hda_intel snd_hda_codec videobuf2_vmalloc videobuf2_memops
> videobuf2_core videodev media ideapad_laptop i2c_core sparse_keymap
> snd_hwdep snd_pcm coretemp rfkill snd_page_alloc evdev serio_raw snd_seq
> snd_seq_device snd_timer snd crc32c_intel aesni_intel aes_i586 aes_generic
> battery ac cryptd power_supply wmi soundcore video button ext4 crc16 jbd2
> mbcache usbhid hid sg sd_mod crc_t10dif microcode xhci_hcd ahci libahci
> r8169 mii libata scsi_mod ehci_hcd fan thermal_sys usbcore usb_common [last
> unloaded: psmouse]
> kern  :warn  : [ 2855.372859]
> kern  :warn  : [ 2855.372862] Pid: 4345, comm: RTAI1 Tainted: G      D
> O 3.4-9-rtai-686-pae #1 LENOVO 80HR/ZHAOYANG E40-80
> kern  :warn  : [ 2855.372866] EIP: 0060:[<f86f2760>] EFLAGS: 00213002 CPU:
> 1
> kern  :warn  : [ 2855.372870] EIP is at rt_rwl_wrlock+0x30/0x200
> [rtai_sched]
> kern  :warn  : [ 2855.372872] EAX: 00000200 EBX: 00000000 ECX: f8702c00
> EDX: 00000000
> kern  :warn  : [ 2855.372874] ESI: 00000030 EDI: 00000201 EBP: f2b19f70
> ESP: f2b19ee4
> kern  :warn  : [ 2855.372876]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
> kern  :warn  : [ 2855.372877] CR0: 80050033 CR2: 0000007c CR3: 36a9f000
> CR4: 001407d0
> kern  :warn  : [ 2855.372879] DR0: 00000000 DR1: 00000000 DR2: 00000000
> DR3: 00000000
> kern  :warn  : [ 2855.372881] DR6: fffe0ff0 DR7: 00000400
> kern  :emerg : [ 2855.372883] Process RTAI1 (pid: 4345, ti=f2b18000
> task=f2b4ad80 task.ti=f2b18000)
> kern  :emerg : [ 2855.372885] I-pipe domain Linux
> kern  :emerg : [ 2855.372886] Stack:
> kern  :warn  : [ 2855.372887]  f77c8e00 d17a140a 00000298 1dcd6500
> f8766220 f86f2730 b74ea324 f86e4375
> kern  :warn  : [ 2855.372894]  00000000 b76514e0 00000000 f8766220
> 003d0f00 b74ea388 08049ab9 00000000
> kern  :warn  : [ 2855.372901]  00000001 c1053a4d f77c8e00 f77c8e00
> f77c8e00 f2b4ad80 f2b4af40 00000001
> kern  :emerg : [ 2855.372908] Call Trace:
> kern  :warn  : [ 2855.372913]  [<f86f2730>] ? rt_rwl_rdlock+0x210/0x210
> [rtai_sched]
> kern  :warn  : [ 2855.372917]  [<f86e4375>] ?
> handle_lxrt_request+0xa5/0xaf0 [rtai_sched]
> kern  :warn  : [ 2855.372922]  [<c1053a4d>] ?
> pick_next_task_fair+0x4d/0x110
> kern  :warn  : [ 2855.372925]  [<c1362a62>] ? __schedule+0x132/0x400
> kern  :warn  : [ 2855.372930]  [<f86e4e18>] ? rtai_lxrt_invoke+0x58/0x180
> [rtai_sched]
> kern  :warn  : [ 2855.372934]  [<f86e3945>] ? lxrt_intercept_syscall+0x75/0x100
> [rtai_sched]
> kern  :warn  : [ 2855.372938]  [<c10e851b>] ? sys_write+0x5b/0x70
> kern  :warn  : [ 2855.372941]  [<c10979ec>] ?
> __ipipe_notify_kevent+0xc/0x10
> kern  :warn  : [ 2855.372944]  [<c101af46>] ?
> __ipipe_syscall_root+0x36/0xd0
> kern  :warn  : [ 2855.372947]  [<c1368bff>] ? sysenter_past_esp+0x5c/0x73
> kern  :emerg : [ 2855.372948] Code: 10 8b 5c 24 20 9c 58 fa 25 00 02 00
> 00 64 8b 15 10 e7 4f c1 f0 0f ab 15 90 d1 72 f8 19 d2 85 d2 0f 84 ed 00 00
> 00 89 c7 8d 73 30 <8b> 43 7c 85 c0 0f 84 85 00 00 00 89 34 24 e8 4d e9 ff
> ff 3d 00
> kern  :emerg : [ 2855.372991] EIP: [<f86f2760>] rt_rwl_wrlock+0x30/0x200
> [rtai_sched] SS:ESP 0068:f2b19ee4
> kern  :warn  : [ 2855.372996] CR2: 000000000000007c
> kern  :warn  : [ 2855.372999] ---[ end trace 61a57933bf2bc264 ]---
> kern  :err   : [ 2855.373002] BUG: Unhandled exception over domain RTAI
> at 0xf86f2760 - switching to ROOT
> kern  :warn  : [ 2855.373004] Pid: 4345, comm: RTAI1 Tainted: G      D
> O 3.4-9-rtai-686-pae #1
> kern  :warn  : [ 2855.373005] Call Trace:
> kern  :warn  : [ 2855.373007]  [<c101adb0>] ? __ipipe_handle_exception+
> 0x220/0x230
> kern  :warn  : [ 2855.373009]  [<f86f2760>] ? rt_rwl_wrlock+0x30/0x200
> [rtai_sched]
> kern  :warn  : [ 2855.373011]  [<c13647f0>] ? error_code+0x6c/0x7c
> kern  :warn  : [ 2855.373013]  [<c104007b>] ? __alloc_workqueue_key+0x36b/
> 0x3e0
> kern  :warn  : [ 2855.373014]  [<f86f2760>] ? rt_rwl_wrlock+0x30/0x200
> [rtai_sched]
> kern  :warn  : [ 2855.373016]  [<f86f2730>] ? rt_rwl_rdlock+0x210/0x210
> [rtai_sched]
> kern  :warn  : [ 2855.373018]  [<f86e4375>] ?
> handle_lxrt_request+0xa5/0xaf0 [rtai_sched]
> kern  :warn  : [ 2855.373020]  [<c1053a4d>] ?
> pick_next_task_fair+0x4d/0x110
> kern  :warn  : [ 2855.373022]  [<c1362a62>] ? __schedule+0x132/0x400
> kern  :warn  : [ 2855.373024]  [<f86e4e18>] ? rtai_lxrt_invoke+0x58/0x180
> [rtai_sched]
> kern  :warn  : [ 2855.373026]  [<f86e3945>] ? lxrt_intercept_syscall+0x75/0x100
> [rtai_sched]
> kern  :warn  : [ 2855.373028]  [<c10e851b>] ? sys_write+0x5b/0x70
> kern  :warn  : [ 2855.373030]  [<c10979ec>] ?
> __ipipe_notify_kevent+0xc/0x10
> kern  :warn  : [ 2855.373032]  [<c101af46>] ?
> __ipipe_syscall_root+0x36/0xd0
> kern  :warn  : [ 2855.373033]  [<c1368bff>] ? sysenter_past_esp+0x5c/0x73
> kern  :info  : [ 2855.373036] note: RTAI1[4345] exited with preempt_count 2
> kern  :warn  : [ 2855.373097] LXRT releases PID 4345 (ID: RTAI1).
> kern  :warn  : [ 3065.563237] LXRT releases PID 4346 (ID: RTAI1).
> kern  :warn  : [ 3065.572713] LXRT releases PID 4344 (ID: RTAI1).
>
> **************************************************
>
>
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