1 // SPDX-License-Identifier: GPL-2.0-or-later 1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* 2 /*
3 * Copyright (C) 2008-2014 Mathieu Desnoyers 3 * Copyright (C) 2008-2014 Mathieu Desnoyers
4 */ 4 */
5 #include <linux/module.h> 5 #include <linux/module.h>
6 #include <linux/mutex.h> 6 #include <linux/mutex.h>
7 #include <linux/types.h> 7 #include <linux/types.h>
8 #include <linux/jhash.h> 8 #include <linux/jhash.h>
9 #include <linux/list.h> 9 #include <linux/list.h>
10 #include <linux/rcupdate.h> 10 #include <linux/rcupdate.h>
11 #include <linux/tracepoint.h> 11 #include <linux/tracepoint.h>
12 #include <linux/err.h> 12 #include <linux/err.h>
13 #include <linux/slab.h> 13 #include <linux/slab.h>
14 #include <linux/sched/signal.h> 14 #include <linux/sched/signal.h>
15 #include <linux/sched/task.h> 15 #include <linux/sched/task.h>
16 #include <linux/static_key.h> 16 #include <linux/static_key.h>
17 17
18 enum tp_func_state { 18 enum tp_func_state {
19 TP_FUNC_0, 19 TP_FUNC_0,
20 TP_FUNC_1, 20 TP_FUNC_1,
21 TP_FUNC_2, 21 TP_FUNC_2,
22 TP_FUNC_N, 22 TP_FUNC_N,
23 }; 23 };
24 24
25 extern tracepoint_ptr_t __start___tracepoints_ 25 extern tracepoint_ptr_t __start___tracepoints_ptrs[];
26 extern tracepoint_ptr_t __stop___tracepoints_p 26 extern tracepoint_ptr_t __stop___tracepoints_ptrs[];
27 27
28 DEFINE_SRCU(tracepoint_srcu); 28 DEFINE_SRCU(tracepoint_srcu);
29 EXPORT_SYMBOL_GPL(tracepoint_srcu); 29 EXPORT_SYMBOL_GPL(tracepoint_srcu);
30 30
31 enum tp_transition_sync { 31 enum tp_transition_sync {
32 TP_TRANSITION_SYNC_1_0_1, 32 TP_TRANSITION_SYNC_1_0_1,
33 TP_TRANSITION_SYNC_N_2_1, 33 TP_TRANSITION_SYNC_N_2_1,
34 34
35 _NR_TP_TRANSITION_SYNC, 35 _NR_TP_TRANSITION_SYNC,
36 }; 36 };
37 37
38 struct tp_transition_snapshot { 38 struct tp_transition_snapshot {
39 unsigned long rcu; 39 unsigned long rcu;
40 unsigned long srcu; 40 unsigned long srcu;
41 bool ongoing; 41 bool ongoing;
42 }; 42 };
43 43
44 /* Protected by tracepoints_mutex */ 44 /* Protected by tracepoints_mutex */
45 static struct tp_transition_snapshot tp_transi 45 static struct tp_transition_snapshot tp_transition_snapshot[_NR_TP_TRANSITION_SYNC];
46 46
47 static void tp_rcu_get_state(enum tp_transitio 47 static void tp_rcu_get_state(enum tp_transition_sync sync)
48 { 48 {
49 struct tp_transition_snapshot *snapsho 49 struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync];
50 50
51 /* Keep the latest get_state snapshot. 51 /* Keep the latest get_state snapshot. */
52 snapshot->rcu = get_state_synchronize_ 52 snapshot->rcu = get_state_synchronize_rcu();
53 snapshot->srcu = start_poll_synchroniz 53 snapshot->srcu = start_poll_synchronize_srcu(&tracepoint_srcu);
54 snapshot->ongoing = true; 54 snapshot->ongoing = true;
55 } 55 }
56 56
57 static void tp_rcu_cond_sync(enum tp_transitio 57 static void tp_rcu_cond_sync(enum tp_transition_sync sync)
58 { 58 {
59 struct tp_transition_snapshot *snapsho 59 struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync];
60 60
61 if (!snapshot->ongoing) 61 if (!snapshot->ongoing)
62 return; 62 return;
63 cond_synchronize_rcu(snapshot->rcu); 63 cond_synchronize_rcu(snapshot->rcu);
64 if (!poll_state_synchronize_srcu(&trac 64 if (!poll_state_synchronize_srcu(&tracepoint_srcu, snapshot->srcu))
65 synchronize_srcu(&tracepoint_s 65 synchronize_srcu(&tracepoint_srcu);
66 snapshot->ongoing = false; 66 snapshot->ongoing = false;
67 } 67 }
68 68
69 /* Set to 1 to enable tracepoint debug output 69 /* Set to 1 to enable tracepoint debug output */
70 static const int tracepoint_debug; 70 static const int tracepoint_debug;
71 71
72 #ifdef CONFIG_MODULES 72 #ifdef CONFIG_MODULES
73 /* 73 /*
74 * Tracepoint module list mutex protects the l 74 * Tracepoint module list mutex protects the local module list.
75 */ 75 */
76 static DEFINE_MUTEX(tracepoint_module_list_mut 76 static DEFINE_MUTEX(tracepoint_module_list_mutex);
77 77
78 /* Local list of struct tp_module */ 78 /* Local list of struct tp_module */
79 static LIST_HEAD(tracepoint_module_list); 79 static LIST_HEAD(tracepoint_module_list);
80 #endif /* CONFIG_MODULES */ 80 #endif /* CONFIG_MODULES */
81 81
82 /* 82 /*
83 * tracepoints_mutex protects the builtin and 83 * tracepoints_mutex protects the builtin and module tracepoints.
84 * tracepoints_mutex nests inside tracepoint_m 84 * tracepoints_mutex nests inside tracepoint_module_list_mutex.
85 */ 85 */
86 static DEFINE_MUTEX(tracepoints_mutex); 86 static DEFINE_MUTEX(tracepoints_mutex);
87 87
88 static struct rcu_head *early_probes; 88 static struct rcu_head *early_probes;
89 static bool ok_to_free_tracepoints; 89 static bool ok_to_free_tracepoints;
90 90
91 /* 91 /*
92 * Note about RCU : 92 * Note about RCU :
93 * It is used to delay the free of multiple pr 93 * It is used to delay the free of multiple probes array until a quiescent
94 * state is reached. 94 * state is reached.
95 */ 95 */
96 struct tp_probes { 96 struct tp_probes {
97 struct rcu_head rcu; 97 struct rcu_head rcu;
98 struct tracepoint_func probes[]; 98 struct tracepoint_func probes[];
99 }; 99 };
100 100
101 /* Called in removal of a func but failed to a 101 /* Called in removal of a func but failed to allocate a new tp_funcs */
102 static void tp_stub_func(void) 102 static void tp_stub_func(void)
103 { 103 {
104 return; 104 return;
105 } 105 }
106 106
107 static inline void *allocate_probes(int count) 107 static inline void *allocate_probes(int count)
108 { 108 {
109 struct tp_probes *p = kmalloc(struct_ 109 struct tp_probes *p = kmalloc(struct_size(p, probes, count),
110 GFP_KER 110 GFP_KERNEL);
111 return p == NULL ? NULL : p->probes; 111 return p == NULL ? NULL : p->probes;
112 } 112 }
113 113
114 static void srcu_free_old_probes(struct rcu_he 114 static void srcu_free_old_probes(struct rcu_head *head)
115 { 115 {
116 kfree(container_of(head, struct tp_pro 116 kfree(container_of(head, struct tp_probes, rcu));
117 } 117 }
118 118
119 static void rcu_free_old_probes(struct rcu_hea 119 static void rcu_free_old_probes(struct rcu_head *head)
120 { 120 {
121 call_srcu(&tracepoint_srcu, head, srcu 121 call_srcu(&tracepoint_srcu, head, srcu_free_old_probes);
122 } 122 }
123 123
124 static __init int release_early_probes(void) 124 static __init int release_early_probes(void)
125 { 125 {
126 struct rcu_head *tmp; 126 struct rcu_head *tmp;
127 127
128 ok_to_free_tracepoints = true; 128 ok_to_free_tracepoints = true;
129 129
130 while (early_probes) { 130 while (early_probes) {
131 tmp = early_probes; 131 tmp = early_probes;
132 early_probes = tmp->next; 132 early_probes = tmp->next;
133 call_rcu(tmp, rcu_free_old_pro 133 call_rcu(tmp, rcu_free_old_probes);
134 } 134 }
135 135
136 return 0; 136 return 0;
137 } 137 }
138 138
139 /* SRCU is initialized at core_initcall */ 139 /* SRCU is initialized at core_initcall */
140 postcore_initcall(release_early_probes); 140 postcore_initcall(release_early_probes);
141 141
142 static inline void release_probes(struct trace 142 static inline void release_probes(struct tracepoint_func *old)
143 { 143 {
144 if (old) { 144 if (old) {
145 struct tp_probes *tp_probes = 145 struct tp_probes *tp_probes = container_of(old,
146 struct tp_probes, prob 146 struct tp_probes, probes[0]);
147 147
148 /* 148 /*
149 * We can't free probes if SRC 149 * We can't free probes if SRCU is not initialized yet.
150 * Postpone the freeing till a 150 * Postpone the freeing till after SRCU is initialized.
151 */ 151 */
152 if (unlikely(!ok_to_free_trace 152 if (unlikely(!ok_to_free_tracepoints)) {
153 tp_probes->rcu.next = 153 tp_probes->rcu.next = early_probes;
154 early_probes = &tp_pro 154 early_probes = &tp_probes->rcu;
155 return; 155 return;
156 } 156 }
157 157
158 /* 158 /*
159 * Tracepoint probes are prote 159 * Tracepoint probes are protected by both sched RCU and SRCU,
160 * by calling the SRCU callbac 160 * by calling the SRCU callback in the sched RCU callback we
161 * cover both cases. So let us 161 * cover both cases. So let us chain the SRCU and sched RCU
162 * callbacks to wait for both 162 * callbacks to wait for both grace periods.
163 */ 163 */
164 call_rcu(&tp_probes->rcu, rcu_ 164 call_rcu(&tp_probes->rcu, rcu_free_old_probes);
165 } 165 }
166 } 166 }
167 167
168 static void debug_print_probes(struct tracepoi 168 static void debug_print_probes(struct tracepoint_func *funcs)
169 { 169 {
170 int i; 170 int i;
171 171
172 if (!tracepoint_debug || !funcs) 172 if (!tracepoint_debug || !funcs)
173 return; 173 return;
174 174
175 for (i = 0; funcs[i].func; i++) 175 for (i = 0; funcs[i].func; i++)
176 printk(KERN_DEBUG "Probe %d : 176 printk(KERN_DEBUG "Probe %d : %p\n", i, funcs[i].func);
177 } 177 }
178 178
179 static struct tracepoint_func * 179 static struct tracepoint_func *
180 func_add(struct tracepoint_func **funcs, struc 180 func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func,
181 int prio) 181 int prio)
182 { 182 {
183 struct tracepoint_func *old, *new; 183 struct tracepoint_func *old, *new;
184 int iter_probes; /* Iterate ove 184 int iter_probes; /* Iterate over old probe array. */
185 int nr_probes = 0; /* Counter for 185 int nr_probes = 0; /* Counter for probes */
186 int pos = -1; /* Insertion p 186 int pos = -1; /* Insertion position into new array */
187 187
188 if (WARN_ON(!tp_func->func)) 188 if (WARN_ON(!tp_func->func))
189 return ERR_PTR(-EINVAL); 189 return ERR_PTR(-EINVAL);
190 190
191 debug_print_probes(*funcs); 191 debug_print_probes(*funcs);
192 old = *funcs; 192 old = *funcs;
193 if (old) { 193 if (old) {
194 /* (N -> N+1), (N != 0, 1) pro 194 /* (N -> N+1), (N != 0, 1) probes */
195 for (iter_probes = 0; old[iter 195 for (iter_probes = 0; old[iter_probes].func; iter_probes++) {
196 if (old[iter_probes].f 196 if (old[iter_probes].func == tp_stub_func)
197 continue; 197 continue; /* Skip stub functions. */
198 if (old[iter_probes].f 198 if (old[iter_probes].func == tp_func->func &&
199 old[iter_probes].d 199 old[iter_probes].data == tp_func->data)
200 return ERR_PTR 200 return ERR_PTR(-EEXIST);
201 nr_probes++; 201 nr_probes++;
202 } 202 }
203 } 203 }
204 /* + 2 : one for new probe, one for NU 204 /* + 2 : one for new probe, one for NULL func */
205 new = allocate_probes(nr_probes + 2); 205 new = allocate_probes(nr_probes + 2);
206 if (new == NULL) 206 if (new == NULL)
207 return ERR_PTR(-ENOMEM); 207 return ERR_PTR(-ENOMEM);
208 if (old) { 208 if (old) {
209 nr_probes = 0; 209 nr_probes = 0;
210 for (iter_probes = 0; old[iter 210 for (iter_probes = 0; old[iter_probes].func; iter_probes++) {
211 if (old[iter_probes].f 211 if (old[iter_probes].func == tp_stub_func)
212 continue; 212 continue;
213 /* Insert before probe 213 /* Insert before probes of lower priority */
214 if (pos < 0 && old[ite 214 if (pos < 0 && old[iter_probes].prio < prio)
215 pos = nr_probe 215 pos = nr_probes++;
216 new[nr_probes++] = old 216 new[nr_probes++] = old[iter_probes];
217 } 217 }
218 if (pos < 0) 218 if (pos < 0)
219 pos = nr_probes++; 219 pos = nr_probes++;
220 /* nr_probes now points to the 220 /* nr_probes now points to the end of the new array */
221 } else { 221 } else {
222 pos = 0; 222 pos = 0;
223 nr_probes = 1; /* must point a 223 nr_probes = 1; /* must point at end of array */
224 } 224 }
225 new[pos] = *tp_func; 225 new[pos] = *tp_func;
226 new[nr_probes].func = NULL; 226 new[nr_probes].func = NULL;
227 *funcs = new; 227 *funcs = new;
228 debug_print_probes(*funcs); 228 debug_print_probes(*funcs);
229 return old; 229 return old;
230 } 230 }
231 231
232 static void *func_remove(struct tracepoint_fun 232 static void *func_remove(struct tracepoint_func **funcs,
233 struct tracepoint_func *tp_fun 233 struct tracepoint_func *tp_func)
234 { 234 {
235 int nr_probes = 0, nr_del = 0, i; 235 int nr_probes = 0, nr_del = 0, i;
236 struct tracepoint_func *old, *new; 236 struct tracepoint_func *old, *new;
237 237
238 old = *funcs; 238 old = *funcs;
239 239
240 if (!old) 240 if (!old)
241 return ERR_PTR(-ENOENT); 241 return ERR_PTR(-ENOENT);
242 242
243 debug_print_probes(*funcs); 243 debug_print_probes(*funcs);
244 /* (N -> M), (N > 1, M >= 0) probes */ 244 /* (N -> M), (N > 1, M >= 0) probes */
245 if (tp_func->func) { 245 if (tp_func->func) {
246 for (nr_probes = 0; old[nr_pro 246 for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
247 if ((old[nr_probes].fu 247 if ((old[nr_probes].func == tp_func->func &&
248 old[nr_probes].da 248 old[nr_probes].data == tp_func->data) ||
249 old[nr_probes].fun 249 old[nr_probes].func == tp_stub_func)
250 nr_del++; 250 nr_del++;
251 } 251 }
252 } 252 }
253 253
254 /* 254 /*
255 * If probe is NULL, then nr_probes = 255 * If probe is NULL, then nr_probes = nr_del = 0, and then the
256 * entire entry will be removed. 256 * entire entry will be removed.
257 */ 257 */
258 if (nr_probes - nr_del == 0) { 258 if (nr_probes - nr_del == 0) {
259 /* N -> 0, (N > 1) */ 259 /* N -> 0, (N > 1) */
260 *funcs = NULL; 260 *funcs = NULL;
261 debug_print_probes(*funcs); 261 debug_print_probes(*funcs);
262 return old; 262 return old;
263 } else { 263 } else {
264 int j = 0; 264 int j = 0;
265 /* N -> M, (N > 1, M > 0) */ 265 /* N -> M, (N > 1, M > 0) */
266 /* + 1 for NULL */ 266 /* + 1 for NULL */
267 new = allocate_probes(nr_probe 267 new = allocate_probes(nr_probes - nr_del + 1);
268 if (new) { 268 if (new) {
269 for (i = 0; old[i].fun 269 for (i = 0; old[i].func; i++) {
270 if ((old[i].fu 270 if ((old[i].func != tp_func->func ||
271 old[i].da 271 old[i].data != tp_func->data) &&
272 old[i].fun 272 old[i].func != tp_stub_func)
273 new[j+ 273 new[j++] = old[i];
274 } 274 }
275 new[nr_probes - nr_del 275 new[nr_probes - nr_del].func = NULL;
276 *funcs = new; 276 *funcs = new;
277 } else { 277 } else {
278 /* 278 /*
279 * Failed to allocate, 279 * Failed to allocate, replace the old function
280 * with calls to tp_st 280 * with calls to tp_stub_func.
281 */ 281 */
282 for (i = 0; old[i].fun 282 for (i = 0; old[i].func; i++) {
283 if (old[i].fun 283 if (old[i].func == tp_func->func &&
284 old[i].dat 284 old[i].data == tp_func->data)
285 WRITE_ 285 WRITE_ONCE(old[i].func, tp_stub_func);
286 } 286 }
287 *funcs = old; 287 *funcs = old;
288 } 288 }
289 } 289 }
290 debug_print_probes(*funcs); 290 debug_print_probes(*funcs);
291 return old; 291 return old;
292 } 292 }
293 293
294 /* 294 /*
295 * Count the number of functions (enum tp_func 295 * Count the number of functions (enum tp_func_state) in a tp_funcs array.
296 */ 296 */
297 static enum tp_func_state nr_func_state(const 297 static enum tp_func_state nr_func_state(const struct tracepoint_func *tp_funcs)
298 { 298 {
299 if (!tp_funcs) 299 if (!tp_funcs)
300 return TP_FUNC_0; 300 return TP_FUNC_0;
301 if (!tp_funcs[1].func) 301 if (!tp_funcs[1].func)
302 return TP_FUNC_1; 302 return TP_FUNC_1;
303 if (!tp_funcs[2].func) 303 if (!tp_funcs[2].func)
304 return TP_FUNC_2; 304 return TP_FUNC_2;
305 return TP_FUNC_N; /* 3 or more * 305 return TP_FUNC_N; /* 3 or more */
306 } 306 }
307 307
308 static void tracepoint_update_call(struct trac 308 static void tracepoint_update_call(struct tracepoint *tp, struct tracepoint_func *tp_funcs)
309 { 309 {
310 void *func = tp->iterator; 310 void *func = tp->iterator;
311 311
312 /* Synthetic events do not have static 312 /* Synthetic events do not have static call sites */
313 if (!tp->static_call_key) 313 if (!tp->static_call_key)
314 return; 314 return;
315 if (nr_func_state(tp_funcs) == TP_FUNC 315 if (nr_func_state(tp_funcs) == TP_FUNC_1)
316 func = tp_funcs[0].func; 316 func = tp_funcs[0].func;
317 __static_call_update(tp->static_call_k 317 __static_call_update(tp->static_call_key, tp->static_call_tramp, func);
318 } 318 }
319 319
320 /* 320 /*
321 * Add the probe function to a tracepoint. 321 * Add the probe function to a tracepoint.
322 */ 322 */
323 static int tracepoint_add_func(struct tracepoi 323 static int tracepoint_add_func(struct tracepoint *tp,
324 struct tracepoi 324 struct tracepoint_func *func, int prio,
325 bool warn) 325 bool warn)
326 { 326 {
327 struct tracepoint_func *old, *tp_funcs 327 struct tracepoint_func *old, *tp_funcs;
328 int ret; 328 int ret;
329 329
330 if (tp->regfunc && !static_key_enabled 330 if (tp->regfunc && !static_key_enabled(&tp->key)) {
331 ret = tp->regfunc(); 331 ret = tp->regfunc();
332 if (ret < 0) 332 if (ret < 0)
333 return ret; 333 return ret;
334 } 334 }
335 335
336 tp_funcs = rcu_dereference_protected(t 336 tp_funcs = rcu_dereference_protected(tp->funcs,
337 lockdep_is_held(&trace 337 lockdep_is_held(&tracepoints_mutex));
338 old = func_add(&tp_funcs, func, prio); 338 old = func_add(&tp_funcs, func, prio);
339 if (IS_ERR(old)) { 339 if (IS_ERR(old)) {
340 WARN_ON_ONCE(warn && PTR_ERR(o 340 WARN_ON_ONCE(warn && PTR_ERR(old) != -ENOMEM);
341 return PTR_ERR(old); 341 return PTR_ERR(old);
342 } 342 }
343 343
344 /* 344 /*
345 * rcu_assign_pointer has as smp_store 345 * rcu_assign_pointer has as smp_store_release() which makes sure
346 * that the new probe callbacks array 346 * that the new probe callbacks array is consistent before setting
347 * a pointer to it. This array is ref 347 * a pointer to it. This array is referenced by __DO_TRACE from
348 * include/linux/tracepoint.h using rc 348 * include/linux/tracepoint.h using rcu_dereference_sched().
349 */ 349 */
350 switch (nr_func_state(tp_funcs)) { 350 switch (nr_func_state(tp_funcs)) {
351 case TP_FUNC_1: /* 0->1 */ 351 case TP_FUNC_1: /* 0->1 */
352 /* 352 /*
353 * Make sure new static func n 353 * Make sure new static func never uses old data after a
354 * 1->0->1 transition sequence 354 * 1->0->1 transition sequence.
355 */ 355 */
356 tp_rcu_cond_sync(TP_TRANSITION 356 tp_rcu_cond_sync(TP_TRANSITION_SYNC_1_0_1);
357 /* Set static call to first fu 357 /* Set static call to first function */
358 tracepoint_update_call(tp, tp_ 358 tracepoint_update_call(tp, tp_funcs);
359 /* Both iterator and static ca 359 /* Both iterator and static call handle NULL tp->funcs */
360 rcu_assign_pointer(tp->funcs, 360 rcu_assign_pointer(tp->funcs, tp_funcs);
361 static_key_enable(&tp->key); 361 static_key_enable(&tp->key);
362 break; 362 break;
363 case TP_FUNC_2: /* 1->2 */ 363 case TP_FUNC_2: /* 1->2 */
364 /* Set iterator static call */ 364 /* Set iterator static call */
365 tracepoint_update_call(tp, tp_ 365 tracepoint_update_call(tp, tp_funcs);
366 /* 366 /*
367 * Iterator callback installed 367 * Iterator callback installed before updating tp->funcs.
368 * Requires ordering between R 368 * Requires ordering between RCU assign/dereference and
369 * static call update/call. 369 * static call update/call.
370 */ 370 */
371 fallthrough; 371 fallthrough;
372 case TP_FUNC_N: /* N->N+1 (N>1 372 case TP_FUNC_N: /* N->N+1 (N>1) */
373 rcu_assign_pointer(tp->funcs, 373 rcu_assign_pointer(tp->funcs, tp_funcs);
374 /* 374 /*
375 * Make sure static func never 375 * Make sure static func never uses incorrect data after a
376 * N->...->2->1 (N>1) transiti 376 * N->...->2->1 (N>1) transition sequence.
377 */ 377 */
378 if (tp_funcs[0].data != old[0] 378 if (tp_funcs[0].data != old[0].data)
379 tp_rcu_get_state(TP_TR 379 tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
380 break; 380 break;
381 default: 381 default:
382 WARN_ON_ONCE(1); 382 WARN_ON_ONCE(1);
383 break; 383 break;
384 } 384 }
385 385
386 release_probes(old); 386 release_probes(old);
387 return 0; 387 return 0;
388 } 388 }
389 389
390 /* 390 /*
391 * Remove a probe function from a tracepoint. 391 * Remove a probe function from a tracepoint.
392 * Note: only waiting an RCU period after sett 392 * Note: only waiting an RCU period after setting elem->call to the empty
393 * function insures that the original callback 393 * function insures that the original callback is not used anymore. This insured
394 * by preempt_disable around the call site. 394 * by preempt_disable around the call site.
395 */ 395 */
396 static int tracepoint_remove_func(struct trace 396 static int tracepoint_remove_func(struct tracepoint *tp,
397 struct tracepoint_func *func) 397 struct tracepoint_func *func)
398 { 398 {
399 struct tracepoint_func *old, *tp_funcs 399 struct tracepoint_func *old, *tp_funcs;
400 400
401 tp_funcs = rcu_dereference_protected(t 401 tp_funcs = rcu_dereference_protected(tp->funcs,
402 lockdep_is_held(&trace 402 lockdep_is_held(&tracepoints_mutex));
403 old = func_remove(&tp_funcs, func); 403 old = func_remove(&tp_funcs, func);
404 if (WARN_ON_ONCE(IS_ERR(old))) 404 if (WARN_ON_ONCE(IS_ERR(old)))
405 return PTR_ERR(old); 405 return PTR_ERR(old);
406 406
407 if (tp_funcs == old) 407 if (tp_funcs == old)
408 /* Failed allocating new tp_fu 408 /* Failed allocating new tp_funcs, replaced func with stub */
409 return 0; 409 return 0;
410 410
411 switch (nr_func_state(tp_funcs)) { 411 switch (nr_func_state(tp_funcs)) {
412 case TP_FUNC_0: /* 1->0 */ 412 case TP_FUNC_0: /* 1->0 */
413 /* Removed last function */ 413 /* Removed last function */
414 if (tp->unregfunc && static_ke 414 if (tp->unregfunc && static_key_enabled(&tp->key))
415 tp->unregfunc(); 415 tp->unregfunc();
416 416
417 static_key_disable(&tp->key); 417 static_key_disable(&tp->key);
418 /* Set iterator static call */ 418 /* Set iterator static call */
419 tracepoint_update_call(tp, tp_ 419 tracepoint_update_call(tp, tp_funcs);
420 /* Both iterator and static ca 420 /* Both iterator and static call handle NULL tp->funcs */
421 rcu_assign_pointer(tp->funcs, 421 rcu_assign_pointer(tp->funcs, NULL);
422 /* 422 /*
423 * Make sure new static func n 423 * Make sure new static func never uses old data after a
424 * 1->0->1 transition sequence 424 * 1->0->1 transition sequence.
425 */ 425 */
426 tp_rcu_get_state(TP_TRANSITION 426 tp_rcu_get_state(TP_TRANSITION_SYNC_1_0_1);
427 break; 427 break;
428 case TP_FUNC_1: /* 2->1 */ 428 case TP_FUNC_1: /* 2->1 */
429 rcu_assign_pointer(tp->funcs, 429 rcu_assign_pointer(tp->funcs, tp_funcs);
430 /* 430 /*
431 * Make sure static func never 431 * Make sure static func never uses incorrect data after a
432 * N->...->2->1 (N>2) transiti 432 * N->...->2->1 (N>2) transition sequence. If the first
433 * element's data has changed, 433 * element's data has changed, then force the synchronization
434 * to prevent current readers 434 * to prevent current readers that have loaded the old data
435 * from calling the new functi 435 * from calling the new function.
436 */ 436 */
437 if (tp_funcs[0].data != old[0] 437 if (tp_funcs[0].data != old[0].data)
438 tp_rcu_get_state(TP_TR 438 tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
439 tp_rcu_cond_sync(TP_TRANSITION 439 tp_rcu_cond_sync(TP_TRANSITION_SYNC_N_2_1);
440 /* Set static call to first fu 440 /* Set static call to first function */
441 tracepoint_update_call(tp, tp_ 441 tracepoint_update_call(tp, tp_funcs);
442 break; 442 break;
443 case TP_FUNC_2: /* N->N-1 (N>2 443 case TP_FUNC_2: /* N->N-1 (N>2) */
444 fallthrough; 444 fallthrough;
445 case TP_FUNC_N: 445 case TP_FUNC_N:
446 rcu_assign_pointer(tp->funcs, 446 rcu_assign_pointer(tp->funcs, tp_funcs);
447 /* 447 /*
448 * Make sure static func never 448 * Make sure static func never uses incorrect data after a
449 * N->...->2->1 (N>2) transiti 449 * N->...->2->1 (N>2) transition sequence.
450 */ 450 */
451 if (tp_funcs[0].data != old[0] 451 if (tp_funcs[0].data != old[0].data)
452 tp_rcu_get_state(TP_TR 452 tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
453 break; 453 break;
454 default: 454 default:
455 WARN_ON_ONCE(1); 455 WARN_ON_ONCE(1);
456 break; 456 break;
457 } 457 }
458 release_probes(old); 458 release_probes(old);
459 return 0; 459 return 0;
460 } 460 }
461 461
462 /** 462 /**
463 * tracepoint_probe_register_prio_may_exist - 463 * tracepoint_probe_register_prio_may_exist - Connect a probe to a tracepoint with priority
464 * @tp: tracepoint 464 * @tp: tracepoint
465 * @probe: probe handler 465 * @probe: probe handler
466 * @data: tracepoint data 466 * @data: tracepoint data
467 * @prio: priority of this function over other 467 * @prio: priority of this function over other registered functions
468 * 468 *
469 * Same as tracepoint_probe_register_prio() ex 469 * Same as tracepoint_probe_register_prio() except that it will not warn
470 * if the tracepoint is already registered. 470 * if the tracepoint is already registered.
471 */ 471 */
472 int tracepoint_probe_register_prio_may_exist(s 472 int tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe,
473 v 473 void *data, int prio)
474 { 474 {
475 struct tracepoint_func tp_func; 475 struct tracepoint_func tp_func;
476 int ret; 476 int ret;
477 477
478 mutex_lock(&tracepoints_mutex); 478 mutex_lock(&tracepoints_mutex);
479 tp_func.func = probe; 479 tp_func.func = probe;
480 tp_func.data = data; 480 tp_func.data = data;
481 tp_func.prio = prio; 481 tp_func.prio = prio;
482 ret = tracepoint_add_func(tp, &tp_func 482 ret = tracepoint_add_func(tp, &tp_func, prio, false);
483 mutex_unlock(&tracepoints_mutex); 483 mutex_unlock(&tracepoints_mutex);
484 return ret; 484 return ret;
485 } 485 }
486 EXPORT_SYMBOL_GPL(tracepoint_probe_register_pr 486 EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio_may_exist);
487 487
488 /** 488 /**
489 * tracepoint_probe_register_prio - Connect a 489 * tracepoint_probe_register_prio - Connect a probe to a tracepoint with priority
490 * @tp: tracepoint 490 * @tp: tracepoint
491 * @probe: probe handler 491 * @probe: probe handler
492 * @data: tracepoint data 492 * @data: tracepoint data
493 * @prio: priority of this function over other 493 * @prio: priority of this function over other registered functions
494 * 494 *
495 * Returns 0 if ok, error value on error. 495 * Returns 0 if ok, error value on error.
496 * Note: if @tp is within a module, the caller 496 * Note: if @tp is within a module, the caller is responsible for
497 * unregistering the probe before the module i 497 * unregistering the probe before the module is gone. This can be
498 * performed either with a tracepoint module g 498 * performed either with a tracepoint module going notifier, or from
499 * within module exit functions. 499 * within module exit functions.
500 */ 500 */
501 int tracepoint_probe_register_prio(struct trac 501 int tracepoint_probe_register_prio(struct tracepoint *tp, void *probe,
502 void *data, 502 void *data, int prio)
503 { 503 {
504 struct tracepoint_func tp_func; 504 struct tracepoint_func tp_func;
505 int ret; 505 int ret;
506 506
507 mutex_lock(&tracepoints_mutex); 507 mutex_lock(&tracepoints_mutex);
508 tp_func.func = probe; 508 tp_func.func = probe;
509 tp_func.data = data; 509 tp_func.data = data;
510 tp_func.prio = prio; 510 tp_func.prio = prio;
511 ret = tracepoint_add_func(tp, &tp_func 511 ret = tracepoint_add_func(tp, &tp_func, prio, true);
512 mutex_unlock(&tracepoints_mutex); 512 mutex_unlock(&tracepoints_mutex);
513 return ret; 513 return ret;
514 } 514 }
515 EXPORT_SYMBOL_GPL(tracepoint_probe_register_pr 515 EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio);
516 516
517 /** 517 /**
518 * tracepoint_probe_register - Connect a prob 518 * tracepoint_probe_register - Connect a probe to a tracepoint
519 * @tp: tracepoint 519 * @tp: tracepoint
520 * @probe: probe handler 520 * @probe: probe handler
521 * @data: tracepoint data 521 * @data: tracepoint data
522 * 522 *
523 * Returns 0 if ok, error value on error. 523 * Returns 0 if ok, error value on error.
524 * Note: if @tp is within a module, the caller 524 * Note: if @tp is within a module, the caller is responsible for
525 * unregistering the probe before the module i 525 * unregistering the probe before the module is gone. This can be
526 * performed either with a tracepoint module g 526 * performed either with a tracepoint module going notifier, or from
527 * within module exit functions. 527 * within module exit functions.
528 */ 528 */
529 int tracepoint_probe_register(struct tracepoin 529 int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data)
530 { 530 {
531 return tracepoint_probe_register_prio( 531 return tracepoint_probe_register_prio(tp, probe, data, TRACEPOINT_DEFAULT_PRIO);
532 } 532 }
533 EXPORT_SYMBOL_GPL(tracepoint_probe_register); 533 EXPORT_SYMBOL_GPL(tracepoint_probe_register);
534 534
535 /** 535 /**
536 * tracepoint_probe_unregister - Disconnect a 536 * tracepoint_probe_unregister - Disconnect a probe from a tracepoint
537 * @tp: tracepoint 537 * @tp: tracepoint
538 * @probe: probe function pointer 538 * @probe: probe function pointer
539 * @data: tracepoint data 539 * @data: tracepoint data
540 * 540 *
541 * Returns 0 if ok, error value on error. 541 * Returns 0 if ok, error value on error.
542 */ 542 */
543 int tracepoint_probe_unregister(struct tracepo 543 int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data)
544 { 544 {
545 struct tracepoint_func tp_func; 545 struct tracepoint_func tp_func;
546 int ret; 546 int ret;
547 547
548 mutex_lock(&tracepoints_mutex); 548 mutex_lock(&tracepoints_mutex);
549 tp_func.func = probe; 549 tp_func.func = probe;
550 tp_func.data = data; 550 tp_func.data = data;
551 ret = tracepoint_remove_func(tp, &tp_f 551 ret = tracepoint_remove_func(tp, &tp_func);
552 mutex_unlock(&tracepoints_mutex); 552 mutex_unlock(&tracepoints_mutex);
553 return ret; 553 return ret;
554 } 554 }
555 EXPORT_SYMBOL_GPL(tracepoint_probe_unregister) 555 EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
556 556
557 static void for_each_tracepoint_range( 557 static void for_each_tracepoint_range(
558 tracepoint_ptr_t *begin, trace 558 tracepoint_ptr_t *begin, tracepoint_ptr_t *end,
559 void (*fct)(struct tracepoint 559 void (*fct)(struct tracepoint *tp, void *priv),
560 void *priv) 560 void *priv)
561 { 561 {
562 tracepoint_ptr_t *iter; 562 tracepoint_ptr_t *iter;
563 563
564 if (!begin) 564 if (!begin)
565 return; 565 return;
566 for (iter = begin; iter < end; iter++) 566 for (iter = begin; iter < end; iter++)
567 fct(tracepoint_ptr_deref(iter) 567 fct(tracepoint_ptr_deref(iter), priv);
568 } 568 }
569 569
570 #ifdef CONFIG_MODULES 570 #ifdef CONFIG_MODULES
571 bool trace_module_has_bad_taint(struct module 571 bool trace_module_has_bad_taint(struct module *mod)
572 { 572 {
573 return mod->taints & ~((1 << TAINT_OOT 573 return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP) |
574 (1 << TAINT_UN 574 (1 << TAINT_UNSIGNED_MODULE) | (1 << TAINT_TEST) |
575 (1 << TAINT_LI 575 (1 << TAINT_LIVEPATCH));
576 } 576 }
577 577
578 static BLOCKING_NOTIFIER_HEAD(tracepoint_notif 578 static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list);
579 579
580 /** 580 /**
581 * register_tracepoint_module_notifier - regis 581 * register_tracepoint_module_notifier - register tracepoint coming/going notifier
582 * @nb: notifier block 582 * @nb: notifier block
583 * 583 *
584 * Notifiers registered with this function are 584 * Notifiers registered with this function are called on module
585 * coming/going with the tracepoint_module_lis 585 * coming/going with the tracepoint_module_list_mutex held.
586 * The notifier block callback should expect a 586 * The notifier block callback should expect a "struct tp_module" data
587 * pointer. 587 * pointer.
588 */ 588 */
589 int register_tracepoint_module_notifier(struct 589 int register_tracepoint_module_notifier(struct notifier_block *nb)
590 { 590 {
591 struct tp_module *tp_mod; 591 struct tp_module *tp_mod;
592 int ret; 592 int ret;
593 593
594 mutex_lock(&tracepoint_module_list_mut 594 mutex_lock(&tracepoint_module_list_mutex);
595 ret = blocking_notifier_chain_register 595 ret = blocking_notifier_chain_register(&tracepoint_notify_list, nb);
596 if (ret) 596 if (ret)
597 goto end; 597 goto end;
598 list_for_each_entry(tp_mod, &tracepoin 598 list_for_each_entry(tp_mod, &tracepoint_module_list, list)
599 (void) nb->notifier_call(nb, M 599 (void) nb->notifier_call(nb, MODULE_STATE_COMING, tp_mod);
600 end: 600 end:
601 mutex_unlock(&tracepoint_module_list_m 601 mutex_unlock(&tracepoint_module_list_mutex);
602 return ret; 602 return ret;
603 } 603 }
604 EXPORT_SYMBOL_GPL(register_tracepoint_module_n 604 EXPORT_SYMBOL_GPL(register_tracepoint_module_notifier);
605 605
606 /** 606 /**
607 * unregister_tracepoint_module_notifier - unr 607 * unregister_tracepoint_module_notifier - unregister tracepoint coming/going notifier
608 * @nb: notifier block 608 * @nb: notifier block
609 * 609 *
610 * The notifier block callback should expect a 610 * The notifier block callback should expect a "struct tp_module" data
611 * pointer. 611 * pointer.
612 */ 612 */
613 int unregister_tracepoint_module_notifier(stru 613 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
614 { 614 {
615 struct tp_module *tp_mod; 615 struct tp_module *tp_mod;
616 int ret; 616 int ret;
617 617
618 mutex_lock(&tracepoint_module_list_mut 618 mutex_lock(&tracepoint_module_list_mutex);
619 ret = blocking_notifier_chain_unregist 619 ret = blocking_notifier_chain_unregister(&tracepoint_notify_list, nb);
620 if (ret) 620 if (ret)
621 goto end; 621 goto end;
622 list_for_each_entry(tp_mod, &tracepoin 622 list_for_each_entry(tp_mod, &tracepoint_module_list, list)
623 (void) nb->notifier_call(nb, M 623 (void) nb->notifier_call(nb, MODULE_STATE_GOING, tp_mod);
624 end: 624 end:
625 mutex_unlock(&tracepoint_module_list_m 625 mutex_unlock(&tracepoint_module_list_mutex);
626 return ret; 626 return ret;
627 627
628 } 628 }
629 EXPORT_SYMBOL_GPL(unregister_tracepoint_module 629 EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier);
630 630
631 /* 631 /*
632 * Ensure the tracer unregistered the module's 632 * Ensure the tracer unregistered the module's probes before the module
633 * teardown is performed. Prevents leaks of pr 633 * teardown is performed. Prevents leaks of probe and data pointers.
634 */ 634 */
635 static void tp_module_going_check_quiescent(st 635 static void tp_module_going_check_quiescent(struct tracepoint *tp, void *priv)
636 { 636 {
637 WARN_ON_ONCE(tp->funcs); 637 WARN_ON_ONCE(tp->funcs);
638 } 638 }
639 639
640 static int tracepoint_module_coming(struct mod 640 static int tracepoint_module_coming(struct module *mod)
641 { 641 {
642 struct tp_module *tp_mod; 642 struct tp_module *tp_mod;
643 643
644 if (!mod->num_tracepoints) 644 if (!mod->num_tracepoints)
645 return 0; 645 return 0;
646 646
647 /* 647 /*
648 * We skip modules that taint the kern 648 * We skip modules that taint the kernel, especially those with different
649 * module headers (for forced load), t 649 * module headers (for forced load), to make sure we don't cause a crash.
650 * Staging, out-of-tree, unsigned GPL, 650 * Staging, out-of-tree, unsigned GPL, and test modules are fine.
651 */ 651 */
652 if (trace_module_has_bad_taint(mod)) 652 if (trace_module_has_bad_taint(mod))
653 return 0; 653 return 0;
654 654
655 tp_mod = kmalloc(sizeof(struct tp_modu 655 tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL);
656 if (!tp_mod) 656 if (!tp_mod)
657 return -ENOMEM; 657 return -ENOMEM;
658 tp_mod->mod = mod; 658 tp_mod->mod = mod;
659 659
660 mutex_lock(&tracepoint_module_list_mut 660 mutex_lock(&tracepoint_module_list_mutex);
661 list_add_tail(&tp_mod->list, &tracepoi 661 list_add_tail(&tp_mod->list, &tracepoint_module_list);
662 blocking_notifier_call_chain(&tracepoi 662 blocking_notifier_call_chain(&tracepoint_notify_list,
663 MODULE_STATE_COMING, t 663 MODULE_STATE_COMING, tp_mod);
664 mutex_unlock(&tracepoint_module_list_m 664 mutex_unlock(&tracepoint_module_list_mutex);
665 return 0; 665 return 0;
666 } 666 }
667 667
668 static void tracepoint_module_going(struct mod 668 static void tracepoint_module_going(struct module *mod)
669 { 669 {
670 struct tp_module *tp_mod; 670 struct tp_module *tp_mod;
671 671
672 if (!mod->num_tracepoints) 672 if (!mod->num_tracepoints)
673 return; 673 return;
674 674
675 mutex_lock(&tracepoint_module_list_mut 675 mutex_lock(&tracepoint_module_list_mutex);
676 list_for_each_entry(tp_mod, &tracepoin 676 list_for_each_entry(tp_mod, &tracepoint_module_list, list) {
677 if (tp_mod->mod == mod) { 677 if (tp_mod->mod == mod) {
678 blocking_notifier_call 678 blocking_notifier_call_chain(&tracepoint_notify_list,
679 MODULE 679 MODULE_STATE_GOING, tp_mod);
680 list_del(&tp_mod->list 680 list_del(&tp_mod->list);
681 kfree(tp_mod); 681 kfree(tp_mod);
682 /* 682 /*
683 * Called the going no 683 * Called the going notifier before checking for
684 * quiescence. 684 * quiescence.
685 */ 685 */
686 for_each_tracepoint_ra 686 for_each_tracepoint_range(mod->tracepoints_ptrs,
687 mod->tracepoin 687 mod->tracepoints_ptrs + mod->num_tracepoints,
688 tp_module_goin 688 tp_module_going_check_quiescent, NULL);
689 break; 689 break;
690 } 690 }
691 } 691 }
692 /* 692 /*
693 * In the case of modules that were ta 693 * In the case of modules that were tainted at "coming", we'll simply
694 * walk through the list without findi 694 * walk through the list without finding it. We cannot use the "tainted"
695 * flag on "going", in case a module t 695 * flag on "going", in case a module taints the kernel only after being
696 * loaded. 696 * loaded.
697 */ 697 */
698 mutex_unlock(&tracepoint_module_list_m 698 mutex_unlock(&tracepoint_module_list_mutex);
699 } 699 }
700 700
701 static int tracepoint_module_notify(struct not 701 static int tracepoint_module_notify(struct notifier_block *self,
702 unsigned long val, void *data) 702 unsigned long val, void *data)
703 { 703 {
704 struct module *mod = data; 704 struct module *mod = data;
705 int ret = 0; 705 int ret = 0;
706 706
707 switch (val) { 707 switch (val) {
708 case MODULE_STATE_COMING: 708 case MODULE_STATE_COMING:
709 ret = tracepoint_module_coming 709 ret = tracepoint_module_coming(mod);
710 break; 710 break;
711 case MODULE_STATE_LIVE: 711 case MODULE_STATE_LIVE:
712 break; 712 break;
713 case MODULE_STATE_GOING: 713 case MODULE_STATE_GOING:
714 tracepoint_module_going(mod); 714 tracepoint_module_going(mod);
715 break; 715 break;
716 case MODULE_STATE_UNFORMED: 716 case MODULE_STATE_UNFORMED:
717 break; 717 break;
718 } 718 }
719 return notifier_from_errno(ret); 719 return notifier_from_errno(ret);
720 } 720 }
721 721
722 static struct notifier_block tracepoint_module 722 static struct notifier_block tracepoint_module_nb = {
723 .notifier_call = tracepoint_module_not 723 .notifier_call = tracepoint_module_notify,
724 .priority = 0, 724 .priority = 0,
725 }; 725 };
726 726
727 static __init int init_tracepoints(void) 727 static __init int init_tracepoints(void)
728 { 728 {
729 int ret; 729 int ret;
730 730
731 ret = register_module_notifier(&tracep 731 ret = register_module_notifier(&tracepoint_module_nb);
732 if (ret) 732 if (ret)
733 pr_warn("Failed to register tr 733 pr_warn("Failed to register tracepoint module enter notifier\n");
734 734
735 return ret; 735 return ret;
736 } 736 }
737 __initcall(init_tracepoints); 737 __initcall(init_tracepoints);
738 #endif /* CONFIG_MODULES */ 738 #endif /* CONFIG_MODULES */
739 739
740 /** 740 /**
741 * for_each_kernel_tracepoint - iteration on a 741 * for_each_kernel_tracepoint - iteration on all kernel tracepoints
742 * @fct: callback 742 * @fct: callback
743 * @priv: private data 743 * @priv: private data
744 */ 744 */
745 void for_each_kernel_tracepoint(void (*fct)(st 745 void for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
746 void *priv) 746 void *priv)
747 { 747 {
748 for_each_tracepoint_range(__start___tr 748 for_each_tracepoint_range(__start___tracepoints_ptrs,
749 __stop___tracepoints_ptrs, fct 749 __stop___tracepoints_ptrs, fct, priv);
750 } 750 }
751 EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint); 751 EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint);
752 752
753 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS 753 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
754 754
755 /* NB: reg/unreg are called while guarded with 755 /* NB: reg/unreg are called while guarded with the tracepoints_mutex */
756 static int sys_tracepoint_refcount; 756 static int sys_tracepoint_refcount;
757 757
758 int syscall_regfunc(void) 758 int syscall_regfunc(void)
759 { 759 {
760 struct task_struct *p, *t; 760 struct task_struct *p, *t;
761 761
762 if (!sys_tracepoint_refcount) { 762 if (!sys_tracepoint_refcount) {
763 read_lock(&tasklist_lock); 763 read_lock(&tasklist_lock);
764 for_each_process_thread(p, t) 764 for_each_process_thread(p, t) {
765 set_task_syscall_work( 765 set_task_syscall_work(t, SYSCALL_TRACEPOINT);
766 } 766 }
767 read_unlock(&tasklist_lock); 767 read_unlock(&tasklist_lock);
768 } 768 }
769 sys_tracepoint_refcount++; 769 sys_tracepoint_refcount++;
770 770
771 return 0; 771 return 0;
772 } 772 }
773 773
774 void syscall_unregfunc(void) 774 void syscall_unregfunc(void)
775 { 775 {
776 struct task_struct *p, *t; 776 struct task_struct *p, *t;
777 777
778 sys_tracepoint_refcount--; 778 sys_tracepoint_refcount--;
779 if (!sys_tracepoint_refcount) { 779 if (!sys_tracepoint_refcount) {
780 read_lock(&tasklist_lock); 780 read_lock(&tasklist_lock);
781 for_each_process_thread(p, t) 781 for_each_process_thread(p, t) {
782 clear_task_syscall_wor 782 clear_task_syscall_work(t, SYSCALL_TRACEPOINT);
783 } 783 }
784 read_unlock(&tasklist_lock); 784 read_unlock(&tasklist_lock);
785 } 785 }
786 } 786 }
787 #endif 787 #endif
788 788
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