nptl_db/td_ta_thr_iter.c

   1 /* Iterate over a process's threads.
   2    Copyright (C) 1999,2000,2001,2002,2003,2004,2007,2008
   3         Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Ulrich Drepper <drepper@redhat.com>, 1999.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 #include "thread_dbP.h"
  22
  23
  24 static td_err_e
  25 iterate_thread_list (td_thragent_t *ta, td_thr_iter_f *callback,
  26                      void *cbdata_p, td_thr_state_e state, int ti_pri,
  27                      psaddr_t head, bool fake_empty, pid_t match_pid)
  28 {
  29   td_err_e err;
  30   psaddr_t next, ofs;
  31   void *copy;
  32
  33   /* Test the state.
  34      XXX This is incomplete.  Normally this test should be in the loop.  */
  35   if (state != TD_THR_ANY_STATE)
  36     return TD_OK;
  37
  38   err = DB_GET_FIELD (next, ta, head, list_t, next, 0);
  39   if (err != TD_OK)
  40     return err;
  41
  42   if (next == 0 && fake_empty)
  43     {
  44       /* __pthread_initialize_minimal has not run.  There is just the main
  45          thread to return.  We cannot rely on its thread register.  They
  46          sometimes contain garbage that would confuse us, left by the
  47          kernel at exec.  So if it looks like initialization is incomplete,
  48          we only fake a special descriptor for the initial thread.  */
  49       td_thrhandle_t th = { ta, 0 };
  50       return callback (&th, cbdata_p) != 0 ? TD_DBERR : TD_OK;
  51     }
  52
  53   /* Cache the offset from struct pthread to its list_t member.  */
  54   err = DB_GET_FIELD_ADDRESS (ofs, ta, 0, pthread, list, 0);
  55   if (err != TD_OK)
  56     return err;
  57
  58   if (ta->ta_sizeof_pthread == 0)
  59     {
  60       err = _td_check_sizeof (ta, &ta->ta_sizeof_pthread, SYM_SIZEOF_pthread);
  61       if (err != TD_OK)
  62         return err;
  63     }
  64   copy = __alloca (ta->ta_sizeof_pthread);
  65
  66   while (next != head)
  67     {
  68       psaddr_t addr, schedpolicy, schedprio;
  69
  70       addr = next - (ofs - (psaddr_t) 0);
  71       if (next == 0 || addr == 0) /* Sanity check.  */
  72         return TD_DBERR;
  73
  74       /* Copy the whole descriptor in once so we can access the several
  75          fields locally.  Excess copying in one go is much better than
  76          multiple ps_pdread calls.  */
  77       if (ps_pdread (ta->ph, addr, copy, ta->ta_sizeof_pthread) != PS_OK)
  78         return TD_ERR;
  79
  80       /* Verify that this thread's pid field matches the child PID.
  81          If its pid field is negative, it's about to do a fork or it
  82          is the sole thread in a fork child.  */
  83       psaddr_t pid;
  84       err = DB_GET_FIELD_LOCAL (pid, ta, copy, pthread, pid, 0);
  85       if (err == TD_OK && (pid_t) (uintptr_t) pid < 0)
  86         {
  87           if (-(pid_t) (uintptr_t) pid == match_pid)
  88             /* It is about to do a fork, but is really still the parent PID.  */
  89             pid = (psaddr_t) (uintptr_t) match_pid;
  90           else
  91             /* It must be a fork child, whose new PID is in the tid field.  */
  92             err = DB_GET_FIELD_LOCAL (pid, ta, copy, pthread, tid, 0);
  93         }
  94       if (err != TD_OK)
  95         break;
  96
  97       if ((pid_t) (uintptr_t) pid == match_pid)
  98         {
  99           err = DB_GET_FIELD_LOCAL (schedpolicy, ta, copy, pthread,
 100                                     schedpolicy, 0);
 101           if (err != TD_OK)
 102             break;
 103           err = DB_GET_FIELD_LOCAL (schedprio, ta, copy, pthread,
 104                                     schedparam_sched_priority, 0);
 105           if (err != TD_OK)
 106             break;
 107
 108           /* Now test whether this thread matches the specified conditions.  */
 109
 110           /* Only if the priority level is as high or higher.  */
 111           int descr_pri = ((uintptr_t) schedpolicy == SCHED_OTHER
 112                            ? 0 : (uintptr_t) schedprio);
 113           if (descr_pri >= ti_pri)
 114             {
 115               /* Yep, it matches.  Call the callback function.  */
 116               td_thrhandle_t th;
 117               th.th_ta_p = (td_thragent_t *) ta;
 118               th.th_unique = addr;
 119               if (callback (&th, cbdata_p) != 0)
 120                 return TD_DBERR;
 121             }
 122         }
 123
 124       /* Get the pointer to the next element.  */
 125       err = DB_GET_FIELD_LOCAL (next, ta, copy + (ofs - (psaddr_t) 0), list_t,
 126                                 next, 0);
 127       if (err != TD_OK)
 128         break;
 129     }
 130
 131   return err;
 132 }
 133
 134
 135 td_err_e
 136 td_ta_thr_iter (const td_thragent_t *ta_arg, td_thr_iter_f *callback,
 137                 void *cbdata_p, td_thr_state_e state, int ti_pri,
 138                 sigset_t *ti_sigmask_p, unsigned int ti_user_flags)
 139 {
 140   td_thragent_t *const ta = (td_thragent_t *) ta_arg;
 141   td_err_e err;
 142   psaddr_t list = 0;
 143
 144   LOG ("td_ta_thr_iter");
 145
 146   /* Test whether the TA parameter is ok.  */
 147   if (! ta_ok (ta))
 148     return TD_BADTA;
 149
 150   /* The thread library keeps two lists for the running threads.  One
 151      list contains the thread which are using user-provided stacks
 152      (this includes the main thread) and the other includes the
 153      threads for which the thread library allocated the stacks.  We
 154      have to iterate over both lists separately.  We start with the
 155      list of threads with user-defined stacks.  */
 156
 157   pid_t pid = ps_getpid (ta->ph);
 158   err = DB_GET_SYMBOL (list, ta, __stack_user);
 159   if (err == TD_OK)
 160     err = iterate_thread_list (ta, callback, cbdata_p, state, ti_pri,
 161                                list, true, pid);
 162
 163   /* And the threads with stacks allocated by the implementation.  */
 164   if (err == TD_OK)
 165     err = DB_GET_SYMBOL (list, ta, stack_used);
 166   if (err == TD_OK)
 167     err = iterate_thread_list (ta, callback, cbdata_p, state, ti_pri,
 168                                list, false, pid);
 169
 170   return err;
 171 }