Commit abd31b57 authored by sasha@mysql.sashanet.com's avatar sasha@mysql.sashanet.com
Browse files

fixes for backtracing, still will not push, just a local commit

parent eccd463b

sql/mysqld.cc

+24 −7
Original line number Diff line number Diff line
@@ -159,6 +159,7 @@ static bool opt_log,opt_update_log,opt_bin_log,opt_slow_log,opt_noacl, 
	    opt_ansi_mode=0,opt_myisam_log=0, opt_large_files=sizeof(my_off_t) > 4;

bool opt_sql_bin_update = 0, opt_log_slave_updates = 0;

FILE *bootstrap_file=0;

int segfaulted = 0; // ensure we do not enter SIGSEGV handler twice

extern MASTER_INFO glob_mi;

extern int init_master_info(MASTER_INFO* mi);
@@ -1039,6 +1040,7 @@ static void init_signals(void) 


#ifdef HAVE_LINUXTHREADS

static sig_handler write_core(int sig);

#ifdef __i386__

#define SIGRETURN_FRAME_COUNT  1

inline static void  trace_stack()

{
@@ -1046,23 +1048,30 @@ inline static void trace_stack() 
  uchar** ebp;

  LINT_INIT(ebp);

  fprintf(stderr, "Attemping backtrace, please send the info below to\

bugs@lists.mysql.com. If you see no messages after this, something is \

 bugs@lists.mysql.com. If you see no messages after this, something  \

 went terribly wrong - report this anyway\n");

  THD* thd = current_thd;

  uint frame_count = 0;

  __asm __volatile__ ("movl %%ebp,%0"

		      :"=r"(ebp)

		      :"r"(ebp));

  if(!ebp)

    {

      fprintf(stderr, "Stack is a mess, frame pointer (ebp) is NULL,\

 aborting backtrace\n");

      return;

    }

  if(!thd)

    {

      fprintf(stderr, "Cannot determing thread while backtraing, ebp=%p",

      fprintf(stderr, "Cannot determine thread, ebp=%p, aborting backtrace\n",

	      ebp);

      return;

    }

  stack_bottom = (uchar**)thd->thread_stack;

  if(ebp > stack_bottom)

  if(ebp > stack_bottom || ebp < stack_bottom - thread_stack)

  {

    fprintf(stderr, "Bogus stack limit, will not backtrace");

    fprintf(stderr,

	    "Bogus stack limit or frame pointer, aborting backtrace\n");

    return;

  }
@@ -1076,7 +1085,7 @@ went terribly wrong - report this anyway\n"); 
      if(new_ebp <= ebp )

	{

	  fprintf(stderr, "New value of ebp failed sanity check\

terminating backtrace");

terminating backtrace\n");

	  return;

	}

      ebp = new_ebp;
@@ -1086,9 +1095,17 @@ terminating backtrace"); 
  fprintf(stderr, "stack trace successful\n"); 

}

#endif

#endif



static sig_handler handle_segfault(int sig)

{

  // strictly speaking, one needs a mutex here

  // but since we have got SIGSEGV already, things are a mess

  // so not having the mutex is not as bad as possibly using a buggy

  // mutex - so we keep things simple

  if(segfaulted)

    return;

  segfaulted = 1;

  fprintf(stderr,"\

mysqld got signal %s in thread %d;  \n\

The manual section 'Debugging a MySQL server' tells you how to use a \n\