[Bug 1687004] Re: multipath crash generating core dump

[Rafael David Tinoco]

The function attributes don't play a role here because this code was
called by a callback and they would warn only at compile time.

(gdb) list log_thread_start 
62	void log_thread_start (pthread_attr_t *attr)
63	{
64		logdbg(stderr,"enter log_thread_start\n");
65	
66		logq_lock = (pthread_mutex_t *) malloc(sizeof(pthread_mutex_t));
67		logev_lock = (pthread_mutex_t *) malloc(sizeof(pthread_mutex_t));
68		logev_cond = (pthread_cond_t *) malloc(sizeof(pthread_cond_t));
69	
70		pthread_mutex_init(logq_lock, NULL);
71		pthread_mutex_init(logev_lock, NULL);
72		pthread_cond_init(logev_cond, NULL);
73	
74		if (log_init("multipathd", 0)) {
75			fprintf(stderr,"can't initialize log buffer\n"); 
76			exit(1);
77		}
78		pthread_create(&log_thr, attr, log_thread, NULL);
79	
80		return;
81	}

Meaning that the code:

71      pthread_mutex_init(logev_lock, NULL);

likely failed to initialize the "logev_lock" pthread_mutex and THAT caused the error and segfault later. 
(From this analysis, this is the real problem to solve)

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https://bugs.launchpad.net/bugs/1687004

Title:
  multipath crash generating core dump

Status in multipath-tools package in Ubuntu:
  In Progress

Bug description:
  It was brought to my attention that:

  multipath-tools: 0.4.9-3ubuntu7.15

  Faced a crash and generated a dump.

  ## multipath (trusty) crashed and its dump shows:

  (gdb) bt full
  #0  __GI___pthread_mutex_lock (mutex=0x0) at ../nptl/pthread_mutex_lock.c:66
          __PRETTY_FUNCTION__ = "__pthread_mutex_lock"
          type = 0
  #1  0x00007f48700b606e in flush_logqueue () at log_pthread.c:39
          empty = 0
  #2  0x00007f48700b611b in log_thread (et=0x0) at log_pthread.c:57
  No locals.
  #3  0x00007f4870964184 in start_thread (arg=0x7f4870d8b700) at pthread_create.c:312
          __res = <optimized out>
          pd = 0x7f4870d8b700
          now = <optimized out>
          unwind_buf = {cancel_jmp_buf = {{jmp_buf = {139949107623680, -3200163692152804016, 0, 0, 139949107624384, 139949107623680, 3244383534590274896, 
                  3244383107817352528}, mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x0, 0x0}, data = {prev = 0x0, cleanup = 0x0, canceltype = 0}}}
          not_first_call = <optimized out>
          pagesize_m1 = <optimized out>
          sp = <optimized out>
          freesize = <optimized out>
          __PRETTY_FUNCTION__ = "start_thread"
  #4  0x00007f486fdb537d in __ecvt_r (value=9.532824124368238e-130, ndigit=0, decpt=0x0, sign=0x0, buf=0x7f4870d8b9c0 "\220R\267pH\177", len=139949107623680)
      at efgcvt_r.c:218
          d = 0
          f = 3.2378592100206092e-319
          exponent = 1893250816
  #5  0x0000000000000000 in ?? ()
  No symbol table info available.

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