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Segmentation fault when setting save_restoreSet_Debug to a non 0 value #17

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ebernalru opened this issue Feb 16, 2018 · 4 comments
Closed

Segmentation fault when setting save_restoreSet_Debug to a non 0 value #17

ebernalru opened this issue Feb 16, 2018 · 4 comments

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@ebernalru
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Dear all,
I have a Segmentation fault when setting save_restoreSet_Debug to a non 0 value. The SegFault is at IOC exit.
My test IOC is under: Debian GNU/Linux 8.10 (jessie), EPICS Base 3.15.3 and autosave: master branch (same error under R5.9 and R5.8)
Here is the GDB output when exiting IOC,

BEGIN save_restoreShow
  Current date-time (yymmdd-hhmmss): [180216-122021] 
  Status: 'No Status' - 'Enabling list...'
  Debug level: 15
  File permissions: 0664
  Save/restore incomplete save sets? YES
  Write dated backup files? YES
  Number of sequence files to maintain: 3
  Time interval between sequence files: 60 seconds
  Time interval between .sav-file write failure and retry: 60 seconds
  NFS host: ''; address:''
  NFS mount point:
    '/home/vagrant/development/iocdata/autosave/ioctest'
  NFS mount status: not managed by save_restore
  I/O errors: 0
  request file path list:
    '/home/vagrant/development/iocdata/autosave/ioctest/'
  save file path:
    '/home/vagrant/development/iocdata/autosave/ioctest'
lockList: listLock=1
  info_settings.req: 
    macro string: ''
    Status PV: 
    Status: 'No Status' - 'Enabling list...'
    Last save time  :Fri Feb 16 12:20:17 2018
    Last backup time:Fri Feb 16 12:20:17 2018
    methods: [ TIMER+CHANGE ]
    path PV: None
    name PV: None
    backups: YES
    save_state = 0x8
    period: 4; trigger chan: ''; monitor period: 5
    last saved file - 
    0 channels not connected (or ca_get failed)

Thread 26 "save_restore" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffdedf5700 (LWP 15561)]
0x0000000000000000 in ?? ()
(gdb) info threads
  Id   Target Id         Frame 
  1    Thread 0x7ffff7fd6740 (LWP 15534) "test" pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
  3    Thread 0x7ffff7fd4700 (LWP 15536) "errlog" pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
  4    Thread 0x7ffff7f53700 (LWP 15538) "timerQueue" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  5    Thread 0x7ffff4d2c700 (LWP 15539) "timerQueue" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  6    Thread 0x7ffff4c2b700 (LWP 15540) "udpTestPortName" __lll_lock_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
  7    Thread 0x7ffff4b2a700 (LWP 15541) "taskwd" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  9    Thread 0x7ffff552d700 (LWP 15543) "test" 0x00007ffff6b33aed in poll () at ../sysdeps/unix/syscall-template.S:81
  10   Thread 0x7ffff49a8700 (LWP 15544) "timerQueue" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  11   Thread 0x7ffff48a7700 (LWP 15545) "cbLow" pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
  12   Thread 0x7ffff46a6700 (LWP 15546) "cbMedium" pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
  13   Thread 0x7ffff44a5700 (LWP 15547) "cbHigh" pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
  14   Thread 0x7ffff42a4700 (LWP 15548) "dbCaLink" pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
  15   Thread 0x7fffdffff700 (LWP 15549) "scanOnce" pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
  16   Thread 0x7fffdfdfe700 (LWP 15550) "scan-10" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  17   Thread 0x7fffdfbfd700 (LWP 15551) "scan-5" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  18   Thread 0x7fffdf9fc700 (LWP 15552) "scan-2" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  19   Thread 0x7fffdf7fb700 (LWP 15553) "scan-1" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  20   Thread 0x7fffdf5fa700 (LWP 15554) "scan-0.5" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  21   Thread 0x7fffdf3f9700 (LWP 15555) "scan-0.2" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  22   Thread 0x7fffdf1f8700 (LWP 15556) "scan-0.1" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  23   Thread 0x7fffdeff7700 (LWP 15557) "CAS-TCP" 0x00007ffff6b3d2dd in accept () at ../sysdeps/unix/syscall-template.S:81
  24   Thread 0x7ffff40a3700 (LWP 15558) "CAS-beacon" 0x00007ffff6b0df2d in nanosleep () at ../sysdeps/unix/syscall-template.S:81
  25   Thread 0x7fffdeef6700 (LWP 15559) "CAS-UDP" 0x00007ffff6b3d543 in recvfrom () at ../sysdeps/unix/syscall-template.S:81
* 26   Thread 0x7fffdedf5700 (LWP 15561) "save_restore" 0x0000000000000000 in ?? ()
  27   Thread 0x7ffff4aa9700 (LWP 15562) "CAC-event" pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
(gdb) thread 26
[Switching to thread 26 (Thread 0x7fffdedf5700 (LWP 15561))]
#0  0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x00007ffff683606e in ca_state (pChan=0x7fffc0000cf0) at ../oldChannelNotify.cpp:644
#2  0x00007ffff7bc56f9 in save_restoreShow (verbose=-1073663648, verbose@entry=1) at ../save_restore.c:2525
#3  0x00007ffff7bcaeb7 in save_restore () at ../save_restore.c:1305
#4  0x00007ffff6e435cc in start_routine (arg=0x6f98e0) at ../../../src/libCom/osi/os/posix/osdThread.c:403
#5  0x00007ffff65d8064 in start_thread (arg=0x7fffdedf5700) at pthread_create.c:309
#6  0x00007ffff6b3c62d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
(gdb) frame 3
#3  0x00007ffff7bcaeb7 in save_restore () at ../save_restore.c:1305
1305			save_restoreShow(1);
(gdb) frame 2
#2  0x00007ffff7bc56f9 in save_restoreShow (verbose=-1073663648, verbose@entry=1) at ../save_restore.c:2525
2525							pchannel->chid, pchannel->chid?ca_state_string[ca_state(pchannel->chid)]:"noChid",
(gdb) frame 1
#1  0x00007ffff683606e in ca_state (pChan=0x7fffc0000cf0) at ../oldChannelNotify.cpp:644
644	    if ( pChan->io.connected ( guard ) ) {
(gdb) frame 0
#0  0x0000000000000000 in ?? ()
(gdb)
@anjohnson
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The autosave module does register and use an epicsAtExit() routine — that's what triggered the output of the long BEGIN save_restoreShow message you posted. However I suspect it's being registered too early so the callback occurs after the CA client library has already cleaned up, which probably explains the NULL pointers in the stack trace.

If a client application wants to be able to use CA resources inside its exit routine, I believe it has to create its CA context before registering the exit routine (so it gets called first at exit time; exit calls are made in the reverse order of their registration).

@timmmooney
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timmmooney commented Feb 19, 2018 via email

@ebernalru
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Thanks for the quick reply,
I tried your modification and It works on my test unit.
Best regards.

@keenanlang
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Fixed in 12aaa9f

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4 participants
@anjohnson @ebernalru @keenanlang @timmmooney