nptl_db/td_ta_thr_iter.c

   1 /* Iterate over a process's threads.
   2    Copyright (C) 1999-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@redhat.com>, 1999.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include "thread_dbP.h"
  21
  22
  23 static td_err_e
  24 iterate_thread_list (td_thragent_t *ta, td_thr_iter_f *callback,
  25                      void *cbdata_p, td_thr_state_e state, int ti_pri,
  26                      psaddr_t head, bool fake_empty, pid_t match_pid)
  27 {
  28   td_err_e err;
  29   psaddr_t next, ofs;
  30   void *copy;
  31
  32   /* Test the state.
  33      XXX This is incomplete.  Normally this test should be in the loop.  */
  34   if (state != TD_THR_ANY_STATE)
  35     return TD_OK;
  36
  37   err = DB_GET_FIELD (next, ta, head, list_t, next, 0);
  38   if (err != TD_OK)
  39     return err;
  40
  41   if (next == 0 && fake_empty)
  42     {
  43       /* __pthread_initialize_minimal has not run.  There is just the main
  44          thread to return.  We cannot rely on its thread register.  They
  45          sometimes contain garbage that would confuse us, left by the
  46          kernel at exec.  So if it looks like initialization is incomplete,
  47          we only fake a special descriptor for the initial thread.  */
  48       td_thrhandle_t th = { ta, 0 };
  49       return callback (&th, cbdata_p) != 0 ? TD_DBERR : TD_OK;
  50     }
  51
  52   /* Cache the offset from struct pthread to its list_t member.  */
  53   err = DB_GET_FIELD_ADDRESS (ofs, ta, 0, pthread, list, 0);
  54   if (err != TD_OK)
  55     return err;
  56
  57   if (ta->ta_sizeof_pthread == 0)
  58     {
  59       err = _td_check_sizeof (ta, &ta->ta_sizeof_pthread, SYM_SIZEOF_pthread);
  60       if (err != TD_OK)
  61         return err;
  62     }
  63   copy = __alloca (ta->ta_sizeof_pthread);
  64
  65   while (next != head)
  66     {
  67       psaddr_t addr, schedpolicy, schedprio;
  68
  69       addr = next - (ofs - (psaddr_t) 0);
  70       if (next == 0 || addr == 0) /* Sanity check.  */
  71         return TD_DBERR;
  72
  73       /* Copy the whole descriptor in once so we can access the several
  74          fields locally.  Excess copying in one go is much better than
  75          multiple ps_pdread calls.  */
  76       if (ps_pdread (ta->ph, addr, copy, ta->ta_sizeof_pthread) != PS_OK)
  77         return TD_ERR;
  78
  79       /* Verify that this thread's pid field matches the child PID.
  80          If its pid field is negative, it's about to do a fork or it
  81          is the sole thread in a fork child.  */
  82       psaddr_t pid;
  83       err = DB_GET_FIELD_LOCAL (pid, ta, copy, pthread, pid, 0);
  84       if (err == TD_OK && (pid_t) (uintptr_t) pid < 0)
  85         {
  86           if (-(pid_t) (uintptr_t) pid == match_pid)
  87             /* It is about to do a fork, but is really still the parent PID.  */
  88             pid = (psaddr_t) (uintptr_t) match_pid;
  89           else
  90             /* It must be a fork child, whose new PID is in the tid field.  */
  91             err = DB_GET_FIELD_LOCAL (pid, ta, copy, pthread, tid, 0);
  92         }
  93       if (err != TD_OK)
  94         break;
  95
  96       if ((pid_t) (uintptr_t) pid == match_pid)
  97         {
  98           err = DB_GET_FIELD_LOCAL (schedpolicy, ta, copy, pthread,
  99                                     schedpolicy, 0);
 100           if (err != TD_OK)
 101             break;
 102           err = DB_GET_FIELD_LOCAL (schedprio, ta, copy, pthread,
 103                                     schedparam_sched_priority, 0);
 104           if (err != TD_OK)
 105             break;
 106
 107           /* Now test whether this thread matches the specified conditions.  */
 108
 109           /* Only if the priority level is as high or higher.  */
 110           int descr_pri = ((uintptr_t) schedpolicy == SCHED_OTHER
 111                            ? 0 : (uintptr_t) schedprio);
 112           if (descr_pri >= ti_pri)
 113             {
 114               /* Yep, it matches.  Call the callback function.  */
 115               td_thrhandle_t th;
 116               th.th_ta_p = (td_thragent_t *) ta;
 117               th.th_unique = addr;
 118               if (callback (&th, cbdata_p) != 0)
 119                 return TD_DBERR;
 120             }
 121         }
 122
 123       /* Get the pointer to the next element.  */
 124       err = DB_GET_FIELD_LOCAL (next, ta, copy + (ofs - (psaddr_t) 0), list_t,
 125                                 next, 0);
 126       if (err != TD_OK)
 127         break;
 128     }
 129
 130   return err;
 131 }
 132
 133
 134 td_err_e
 135 td_ta_thr_iter (const td_thragent_t *ta_arg, td_thr_iter_f *callback,
 136                 void *cbdata_p, td_thr_state_e state, int ti_pri,
 137                 sigset_t *ti_sigmask_p, unsigned int ti_user_flags)
 138 {
 139   td_thragent_t *const ta = (td_thragent_t *) ta_arg;
 140   td_err_e err;
 141   psaddr_t list = 0;
 142
 143   LOG ("td_ta_thr_iter");
 144
 145   /* Test whether the TA parameter is ok.  */
 146   if (! ta_ok (ta))
 147     return TD_BADTA;
 148
 149   /* The thread library keeps two lists for the running threads.  One
 150      list contains the thread which are using user-provided stacks
 151      (this includes the main thread) and the other includes the
 152      threads for which the thread library allocated the stacks.  We
 153      have to iterate over both lists separately.  We start with the
 154      list of threads with user-defined stacks.  */
 155
 156   pid_t pid = ps_getpid (ta->ph);
 157   err = DB_GET_SYMBOL (list, ta, __stack_user);
 158   if (err == TD_OK)
 159     err = iterate_thread_list (ta, callback, cbdata_p, state, ti_pri,
 160                                list, true, pid);
 161
 162   /* And the threads with stacks allocated by the implementation.  */
 163   if (err == TD_OK)
 164     err = DB_GET_SYMBOL (list, ta, stack_used);
 165   if (err == TD_OK)
 166     err = iterate_thread_list (ta, callback, cbdata_p, state, ti_pri,
 167                                list, false, pid);
 168
 169   return err;
 170 }