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2024-10-09 244b2c5ca8b14627e4a17755e5922221e121c771 
 kernel/kernel/signal.c
....@@ -20,7 +20,6 @@
2020 #include <linux/sched/task.h>
2121 #include <linux/sched/task_stack.h>
2222 #include <linux/sched/cputime.h>
23
-#include <linux/sched/rt.h>
2423 #include <linux/file.h>
2524 #include <linux/fs.h>
2625 #include <linux/proc_fs.h>
....@@ -408,30 +407,13 @@
408407 	task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
409408 }
410409 
411
-static inline struct sigqueue *get_task_cache(struct task_struct *t)
412
-{
413
-	struct sigqueue *q = t->sigqueue_cache;
414
-
415
-	if (cmpxchg(&t->sigqueue_cache, q, NULL) != q)
416
-		return NULL;
417
-	return q;
418
-}
419
-
420
-static inline int put_task_cache(struct task_struct *t, struct sigqueue *q)
421
-{
422
-	if (cmpxchg(&t->sigqueue_cache, NULL, q) == NULL)
423
-		return 0;
424
-	return 1;
425
-}
426
-
427410 /*
428411  * allocate a new signal queue record
429412  * - this may be called without locks if and only if t == current, otherwise an
430413  *   appropriate lock must be held to stop the target task from exiting
431414  */
432415 static struct sigqueue *
433
-__sigqueue_do_alloc(int sig, struct task_struct *t, gfp_t flags,
434
-		    int override_rlimit, int fromslab)
416
+__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
435417 {
436418 	struct sigqueue *q = NULL;
437419 	struct user_struct *user;
....@@ -453,10 +435,7 @@
453435 	rcu_read_unlock();
454436 
455437 	if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
456
-		if (!fromslab)
457
-			q = get_task_cache(t);
458
-		if (!q)
459
-			q = kmem_cache_alloc(sigqueue_cachep, flags);
438
+		q = kmem_cache_alloc(sigqueue_cachep, flags);
460439 	} else {
461440 		print_dropped_signal(sig);
462441 	}
....@@ -473,13 +452,6 @@
473452 	return q;
474453 }
475454 
476
-static struct sigqueue *
477
-__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags,
478
-		 int override_rlimit)
479
-{
480
-	return __sigqueue_do_alloc(sig, t, flags, override_rlimit, 0);
481
-}
482
-
483455 static void __sigqueue_free(struct sigqueue *q)
484456 {
485457 	if (q->flags & SIGQUEUE_PREALLOC)
....@@ -487,21 +459,6 @@
487459 	if (atomic_dec_and_test(&q->user->sigpending))
488460 		free_uid(q->user);
489461 	kmem_cache_free(sigqueue_cachep, q);
490
-}
491
-
492
-static void sigqueue_free_current(struct sigqueue *q)
493
-{
494
-	struct user_struct *up;
495
-
496
-	if (q->flags & SIGQUEUE_PREALLOC)
497
-		return;
498
-
499
-	up = q->user;
500
-	if (rt_prio(current->normal_prio) && !put_task_cache(current, q)) {
501
-		if (atomic_dec_and_test(&up->sigpending))
502
-			free_uid(up);
503
-	} else
504
-		  __sigqueue_free(q);
505462 }
506463 
507464 void flush_sigqueue(struct sigpending *queue)
....@@ -514,21 +471,6 @@
514471 		list_del_init(&q->list);
515472 		__sigqueue_free(q);
516473 	}
517
-}
518
-
519
-/*
520
- * Called from __exit_signal. Flush tsk->pending and
521
- * tsk->sigqueue_cache
522
- */
523
-void flush_task_sigqueue(struct task_struct *tsk)
524
-{
525
-	struct sigqueue *q;
526
-
527
-	flush_sigqueue(&tsk->pending);
528
-
529
-	q = get_task_cache(tsk);
530
-	if (q)
531
-		kmem_cache_free(sigqueue_cachep, q);
532474 }
533475 
534476 /*
....@@ -655,7 +597,7 @@
655597 			(info->si_code == SI_TIMER) &&
656598 			(info->si_sys_private);
657599 
658
-		sigqueue_free_current(first);
600
+		__sigqueue_free(first);
659601 	} else {
660602 		/*
661603 		 * Ok, it wasn't in the queue.  This must be
....@@ -691,8 +633,6 @@
691633 {
692634 	bool resched_timer = false;
693635 	int signr;
694
-
695
-	WARN_ON_ONCE(tsk != current);
696636 
697637 	/* We only dequeue private signals from ourselves, we don't let
698638 	 * signalfd steal them
....@@ -1377,34 +1317,6 @@
13771317 	struct k_sigaction *action;
13781318 	int sig = info->si_signo;
13791319 
1380
-	/*
1381
-	 * On some archs, PREEMPT_RT has to delay sending a signal from a trap
1382
-	 * since it can not enable preemption, and the signal code's spin_locks
1383
-	 * turn into mutexes. Instead, it must set TIF_NOTIFY_RESUME which will
1384
-	 * send the signal on exit of the trap.
1385
-	 */
1386
-#ifdef ARCH_RT_DELAYS_SIGNAL_SEND
1387
-	if (in_atomic()) {
1388
-		struct task_struct *t = current;
1389
-
1390
-		if (WARN_ON_ONCE(t->forced_info.si_signo))
1391
-			return 0;
1392
-
1393
-		if (is_si_special(info)) {
1394
-			WARN_ON_ONCE(info != SEND_SIG_PRIV);
1395
-			t->forced_info.si_signo = info->si_signo;
1396
-			t->forced_info.si_errno = 0;
1397
-			t->forced_info.si_code = SI_KERNEL;
1398
-			t->forced_info.si_pid = 0;
1399
-			t->forced_info.si_uid = 0;
1400
-		} else {
1401
-			t->forced_info = *info;
1402
-		}
1403
-
1404
-		set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
1405
-		return 0;
1406
-	}
1407
-#endif
14081320 	spin_lock_irqsave(&t->sighand->siglock, flags);
14091321 	action = &t->sighand->action[sig-1];
14101322 	ignored = action->sa.sa_handler == SIG_IGN;
....@@ -1907,8 +1819,7 @@
19071819  */
19081820 struct sigqueue *sigqueue_alloc(void)
19091821 {
1910
-	/* Preallocated sigqueue objects always from the slabcache ! */
1911
-	struct sigqueue *q = __sigqueue_do_alloc(-1, current, GFP_KERNEL, 0, 1);
1822
+	struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
19121823 
19131824 	if (q)
19141825 		q->flags |= SIGQUEUE_PREALLOC;
....@@ -2294,8 +2205,16 @@
22942205 		if (gstop_done && ptrace_reparented(current))
22952206 			do_notify_parent_cldstop(current, false, why);
22962207 
2208
+		/*
2209
+		 * Don't want to allow preemption here, because
2210
+		 * sys_ptrace() needs this task to be inactive.
2211
+		 *
2212
+		 * XXX: implement read_unlock_no_resched().
2213
+		 */
2214
+		preempt_disable();
22972215 		read_unlock(&tasklist_lock);
22982216 		cgroup_enter_frozen();
2217
+		preempt_enable_no_resched();
22992218 		freezable_schedule();
23002219 		cgroup_leave_frozen(true);
23012220 	} else {