[Bug 884676] Re: [ARM] pthread_cond_wait hang

[Dr. David Alan Gilbert]

** Attachment added: "test routine"
   https://bugs.launchpad.net/bugs/884676/+attachment/2581478/+files/pthreadtest.c

** Changed in: eglibc (Ubuntu)
     Assignee: (unassigned) => Dr. David Alan Gilbert (davidgil-uk)

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Title:
  [ARM] pthread_cond_wait hang

Status in “eglibc” package in Ubuntu:
  New

Bug description:
  The attached test program hangs on ARM, but works fine on x86.
  It's based on the thread_init code in memcached that exhibits the same symptoms.

  Tested on Panda-A1 (Dual core cortex-A9) in an Oneiric chroot:
  ii  libc6                             2.13-20ubuntu5                          Embedded GNU C Library: Shared libraries

  main install is a Linaro 11.09 (Natty based filesystem), the kernel is

  Linux panda-01 3.0.0-1404-linaro-lt-omap #8~ppa~natty-Ubuntu SMP
  PREEMPT Wed Sep 28 17:16:15 UTC 2011 armv7l armv7l armv7l GNU/Linux

  It fails about 1/100ish times, so I run it with:
  for SEQ in `seq 1 200`; do  echo $SEQ; ./pthreadtest; done

  gdb shows it's hanging trying to get the lock for the cond data:
  gdb 
  GNU gdb (Ubuntu/Linaro 7.3-0ubuntu2) 7.3-2011.08
  Copyright (C) 2011 Free Software Foundation, Inc.
  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
  This is free software: you are free to change and redistribute it.
  There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
  and "show warranty" for details.
  This GDB was configured as "arm-linux-gnueabi".
  For bug reporting instructions, please see:
  <http://bugs.launchpad.net/gdb-linaro/>.
  (gdb) attach 2511
  Attaching to process 2511
  Reading symbols from /home/dg/pthreadtest...(no debugging symbols found)...done.
  Reading symbols from /lib/arm-linux-gnueabi/libpthread.so.0...Reading symbols from /usr/lib/debug/lib/arm-linux-gnueabi/libpthread-2.13.so...done.
  [Thread debugging using libthread_db enabled]
  [New Thread 0x42c1c470 (LWP 2516)]
  [New Thread 0x423bf470 (LWP 2515)]
  [New Thread 0x41b3a470 (LWP 2514)]
  [New Thread 0x412aa470 (LWP 2513)]
  [New Thread 0x409fe470 (LWP 2512)]
  done.
  Loaded symbols for /lib/arm-linux-gnueabi/libpthread.so.0
  Reading symbols from /lib/arm-linux-gnueabi/libc.so.6...Reading symbols from /usr/lib/debug/lib/arm-linux-gnueabi/libc-2.13.so...done.
  done.
  Loaded symbols for /lib/arm-linux-gnueabi/libc.so.6
  Reading symbols from /lib/ld-linux.so.3...(no debugging symbols found)...done.
  Loaded symbols for /lib/ld-linux.so.3
  __libc_do_syscall ()
      at ../ports/sysdeps/unix/sysv/linux/arm/eabi/libc-do-syscall.S:46
  46	../ports/sysdeps/unix/sysv/linux/arm/eabi/libc-do-syscall.S: No such file or directory.
  	in ../ports/sysdeps/unix/sysv/linux/arm/eabi/libc-do-syscall.S
  (gdb) bt full
  #0  __libc_do_syscall ()
      at ../ports/sysdeps/unix/sysv/linux/arm/eabi/libc-do-syscall.S:46
  No locals.
  #1  0x40081608 in __lll_lock_wait (futex=0x11088, private=0)
      at ../ports/sysdeps/unix/sysv/linux/arm/nptl/lowlevellock.c:47
          _a2tmp = 128
          _a2 = <optimized out>
          _nametmp = 240
          _a3tmp = 2
          _a3 = <optimized out>
          _a1 = <optimized out>
          _a4tmp = 0
          _a1tmp = 69768
          _a4 = <optimized out>
          _name = <optimized out>
          oldval = <optimized out>
  #2  0x4007f58e in __pthread_cond_wait (cond=0x11088, mutex=0x11068)
      at pthread_cond_wait.c:159
          __futex = 0x11088
          futex_val = 1
          buffer = {__routine = 0x4007f261 <__condvar_cleanup>, 
            __arg = 0xbe800bd8, __canceltype = 1119993776, __prev = 0x0}
          cbuffer = {oldtype = 0, cond = 0x11088, mutex = 0x11068, bc_seq = 0}
          err = <optimized out>
          pshared = 0
          val = <optimized out>
          seq = 0
  #3  0x000087e4 in thread_init ()
  No symbol table info available.
  #4  0x00008694 in main ()
  No symbol table info available.
  (gdb) q
  A debugging session is active.

          Inferior 1 [process 2511] will be detached.

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