nptl_db/td_ta_thr_iter.c

   1 /* Iterate over a process's threads.
   2    Copyright (C) 1999-2020 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    <https://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)
  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       err = DB_GET_FIELD_LOCAL (schedpolicy, ta, copy, pthread,
  80                                 schedpolicy, 0);
  81       if (err != TD_OK)
  82         break;
  83       err = DB_GET_FIELD_LOCAL (schedprio, ta, copy, pthread,
  84                                 schedparam_sched_priority, 0);
  85       if (err != TD_OK)
  86         break;
  87
  88       /* Now test whether this thread matches the specified conditions.  */
  89
  90       /* Only if the priority level is as high or higher.  */
  91       int descr_pri = ((uintptr_t) schedpolicy == SCHED_OTHER
  92                        ? 0 : (uintptr_t) schedprio);
  93       if (descr_pri >= ti_pri)
  94         {
  95           /* Yep, it matches.  Call the callback function.  */
  96           td_thrhandle_t th;
  97           th.th_ta_p = (td_thragent_t *) ta;
  98           th.th_unique = addr;
  99           if (callback (&th, cbdata_p) != 0)
 100             return TD_DBERR;
 101         }
 102
 103       /* Get the pointer to the next element.  */
 104       err = DB_GET_FIELD_LOCAL (next, ta, copy + (ofs - (psaddr_t) 0), list_t,
 105                                 next, 0);
 106       if (err != TD_OK)
 107         break;
 108     }
 109
 110   return err;
 111 }
 112
 113
 114 td_err_e
 115 td_ta_thr_iter (const td_thragent_t *ta_arg, td_thr_iter_f *callback,
 116                 void *cbdata_p, td_thr_state_e state, int ti_pri,
 117                 sigset_t *ti_sigmask_p, unsigned int ti_user_flags)
 118 {
 119   td_thragent_t *const ta = (td_thragent_t *) ta_arg;
 120   td_err_e err;
 121   psaddr_t list = 0;
 122
 123   LOG ("td_ta_thr_iter");
 124
 125   /* Test whether the TA parameter is ok.  */
 126   if (! ta_ok (ta))
 127     return TD_BADTA;
 128
 129   /* The thread library keeps two lists for the running threads.  One
 130      list contains the thread which are using user-provided stacks
 131      (this includes the main thread) and the other includes the
 132      threads for which the thread library allocated the stacks.  We
 133      have to iterate over both lists separately.  We start with the
 134      list of threads with user-defined stacks.  */
 135
 136   err = __td_ta_stack_user (ta, &list);
 137   if (err == TD_OK)
 138     err = iterate_thread_list (ta, callback, cbdata_p, state, ti_pri,
 139                                list, true);
 140
 141   /* And the threads with stacks allocated by the implementation.  */
 142   if (err == TD_OK)
 143     err = __td_ta_stack_used (ta, &list);
 144   if (err == TD_OK)
 145     err = iterate_thread_list (ta, callback, cbdata_p, state, ti_pri,
 146                                list, false);
 147
 148   return err;
 149 }