kernel_5.10 no rt

hc

2023-12-11 6778948f9de86c3cfaf36725a7c87dcff9ba247f

 kernel/kernel/locking/rtmutex-debug.c
..
..
@@ -32,10 +32,108 @@
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 #include "rtmutex_common.h"
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+static void printk_task(struct task_struct *p)
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+{
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+	if (p)
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+		printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);
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+	else
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+		printk("<none>");
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+}
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+
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+static void printk_lock(struct rt_mutex *lock, int print_owner)
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+{
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+	if (lock->name)
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+		printk(" [%p] {%s}\n",
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+			lock, lock->name);
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+	else
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+		printk(" [%p] {%s:%d}\n",
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+			lock, lock->file, lock->line);
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+
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+	if (print_owner && rt_mutex_owner(lock)) {
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+		printk(".. ->owner: %p\n", lock->owner);
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+		printk(".. held by:  ");
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+		printk_task(rt_mutex_owner(lock));
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+		printk("\n");
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+	}
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+}
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+
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 void rt_mutex_debug_task_free(struct task_struct *task)
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 {
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 	DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters.rb_root));
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 	DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
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+}
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+
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+/*
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+ * We fill out the fields in the waiter to store the information about
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+ * the deadlock. We print when we return. act_waiter can be NULL in
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+ * case of a remove waiter operation.
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+ */
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+void debug_rt_mutex_deadlock(enum rtmutex_chainwalk chwalk,
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+			     struct rt_mutex_waiter *act_waiter,
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+			     struct rt_mutex *lock)
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+{
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+	struct task_struct *task;
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+
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+	if (!debug_locks || chwalk == RT_MUTEX_FULL_CHAINWALK || !act_waiter)
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+		return;
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+
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+	task = rt_mutex_owner(act_waiter->lock);
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+	if (task && task != current) {
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+		act_waiter->deadlock_task_pid = get_pid(task_pid(task));
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+		act_waiter->deadlock_lock = lock;
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+	}
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+}
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+
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+void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
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+{
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+	struct task_struct *task;
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+
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+	if (!waiter->deadlock_lock || !debug_locks)
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+		return;
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+
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+	rcu_read_lock();
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+	task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
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+	if (!task) {
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+		rcu_read_unlock();
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+		return;
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+	}
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+
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+	if (!debug_locks_off()) {
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+		rcu_read_unlock();
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+		return;
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+	}
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+
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+	pr_warn("\n");
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+	pr_warn("============================================\n");
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+	pr_warn("WARNING: circular locking deadlock detected!\n");
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+	pr_warn("%s\n", print_tainted());
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+	pr_warn("--------------------------------------------\n");
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+	printk("%s/%d is deadlocking current task %s/%d\n\n",
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+	       task->comm, task_pid_nr(task),
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+	       current->comm, task_pid_nr(current));
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+
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+	printk("\n1) %s/%d is trying to acquire this lock:\n",
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+	       current->comm, task_pid_nr(current));
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+	printk_lock(waiter->lock, 1);
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+
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+	printk("\n2) %s/%d is blocked on this lock:\n",
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+		task->comm, task_pid_nr(task));
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+	printk_lock(waiter->deadlock_lock, 1);
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+
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+	debug_show_held_locks(current);
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+	debug_show_held_locks(task);
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+
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+	printk("\n%s/%d's [blocked] stackdump:\n\n",
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+		task->comm, task_pid_nr(task));
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+	show_stack(task, NULL, KERN_DEFAULT);
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+	printk("\n%s/%d's [current] stackdump:\n\n",
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+		current->comm, task_pid_nr(current));
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+	dump_stack();
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+	debug_show_all_locks();
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+	rcu_read_unlock();
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+
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+	printk("[ turning off deadlock detection."
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+	       "Please report this trace. ]\n\n");
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 }
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138
 
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 void debug_rt_mutex_lock(struct rt_mutex *lock)
..
..
@@ -60,10 +158,12 @@
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 void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
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 {
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 	memset(waiter, 0x11, sizeof(*waiter));
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+	waiter->deadlock_task_pid = NULL;
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162
 }
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163
 
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 void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
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 {
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+	put_pid(waiter->deadlock_task_pid);
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 	memset(waiter, 0x22, sizeof(*waiter));
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 }
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169
 
..
..
@@ -73,8 +173,10 @@
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 	 * Make sure we are not reinitializing a held lock:
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 	 */
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 	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
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+	lock->name = name;
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177
 
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 #ifdef CONFIG_DEBUG_LOCK_ALLOC
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 	lockdep_init_map(&lock->dep_map, name, key, 0);
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 #endif
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 }
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+