1 /* Iterate over a process's threads.
2 Copyright (C) 1999-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include "thread_dbP.h"
20
21
22 static td_err_e
23 iterate_thread_list (td_thragent_t *ta, td_thr_iter_f *callback,
24 void *cbdata_p, td_thr_state_e state, int ti_pri,
25 psaddr_t head, bool fake_empty)
26 {
27 td_err_e err;
28 psaddr_t next, ofs;
29 void *copy;
30
31 /* Test the state.
32 XXX This is incomplete. Normally this test should be in the loop. */
33 if (state != TD_THR_ANY_STATE)
34 return TD_OK;
35
36 err = DB_GET_FIELD (next, ta, head, list_t, next, 0);
37 if (err != TD_OK)
38 return err;
39
40 if (next == 0 && fake_empty)
41 {
42 /* __pthread_initialize_minimal has not run. There is just the main
43 thread to return. We cannot rely on its thread register. They
44 sometimes contain garbage that would confuse us, left by the
45 kernel at exec. So if it looks like initialization is incomplete,
46 we only fake a special descriptor for the initial thread. */
47 td_thrhandle_t th = { ta, 0 };
48 return callback (&th, cbdata_p) != 0 ? TD_DBERR : TD_OK;
49 }
50
51 /* Cache the offset from struct pthread to its list_t member. */
52 err = DB_GET_FIELD_ADDRESS (ofs, ta, 0, pthread, list, 0);
53 if (err != TD_OK)
54 return err;
55
56 if (ta->ta_sizeof_pthread == 0)
57 {
58 err = _td_check_sizeof (ta, &ta->ta_sizeof_pthread, SYM_SIZEOF_pthread);
59 if (err != TD_OK)
60 return err;
61 }
62 copy = __alloca (ta->ta_sizeof_pthread);
63
64 while (next != head)
65 {
66 psaddr_t addr, schedpolicy, schedprio;
67
68 addr = next - (ofs - (psaddr_t) 0);
69 if (next == 0 || addr == 0) /* Sanity check. */
70 return TD_DBERR;
71
72 /* Copy the whole descriptor in once so we can access the several
73 fields locally. Excess copying in one go is much better than
74 multiple ps_pdread calls. */
75 if (ps_pdread (ta->ph, addr, copy, ta->ta_sizeof_pthread) != PS_OK)
76 return TD_ERR;
77
78 err = DB_GET_FIELD_LOCAL (schedpolicy, ta, copy, pthread,
79 schedpolicy, 0);
80 if (err != TD_OK)
81 break;
82 err = DB_GET_FIELD_LOCAL (schedprio, ta, copy, pthread,
83 schedparam_sched_priority, 0);
84 if (err != TD_OK)
85 break;
86
87 /* Now test whether this thread matches the specified conditions. */
88
89 /* Only if the priority level is as high or higher. */
90 int descr_pri = ((uintptr_t) schedpolicy == SCHED_OTHER
91 ? 0 : (uintptr_t) schedprio);
92 if (descr_pri >= ti_pri)
93 {
94 /* Yep, it matches. Call the callback function. */
95 td_thrhandle_t th;
96 th.th_ta_p = (td_thragent_t *) ta;
97 th.th_unique = addr;
98 if (callback (&th, cbdata_p) != 0)
99 return TD_DBERR;
100 }
101
102 /* Get the pointer to the next element. */
103 err = DB_GET_FIELD_LOCAL (next, ta, copy + (ofs - (psaddr_t) 0), list_t,
104 next, 0);
105 if (err != TD_OK)
106 break;
107 }
108
109 return err;
110 }
111
112
113 td_err_e
114 td_ta_thr_iter (const td_thragent_t *ta_arg, td_thr_iter_f *callback,
115 void *cbdata_p, td_thr_state_e state, int ti_pri,
116 sigset_t *ti_sigmask_p, unsigned int ti_user_flags)
117 {
118 td_thragent_t *const ta = (td_thragent_t *) ta_arg;
119 td_err_e err;
120 psaddr_t list = 0;
121
122 LOG ("td_ta_thr_iter");
123
124 /* Test whether the TA parameter is ok. */
125 if (! ta_ok (ta))
126 return TD_BADTA;
127
128 /* The thread library keeps two lists for the running threads. One
129 list contains the thread which are using user-provided stacks
130 (this includes the main thread) and the other includes the
131 threads for which the thread library allocated the stacks. We
132 have to iterate over both lists separately. We start with the
133 list of threads with user-defined stacks. */
134
135 err = __td_ta_stack_user (ta, &list);
136 if (err == TD_OK)
137 err = iterate_thread_list (ta, callback, cbdata_p, state, ti_pri,
138 list, true);
139
140 /* And the threads with stacks allocated by the implementation. */
141 if (err == TD_OK)
142 err = __td_ta_stack_used (ta, &list);
143 if (err == TD_OK)
144 err = iterate_thread_list (ta, callback, cbdata_p, state, ti_pri,
145 list, false);
146
147 return err;
148 }