修改4g拨号为QMI,需要在系统里后台执行quectel-CM

hc

2024-10-22 8ac6c7a54ed1b98d142dce24b11c6de6a1e239a5

 kernel/include/linux/sched/task.h
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@@ -61,7 +61,9 @@
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 extern void sched_dead(struct task_struct *p);
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 void __noreturn do_task_dead(void);
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+void __noreturn make_task_dead(int signr);
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+extern void mm_cache_init(void);
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 extern void proc_caches_init(void);
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 extern void fork_init(void);
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@@ -88,7 +90,6 @@
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 extern pid_t kernel_clone(struct kernel_clone_args *kargs);
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 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
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 struct task_struct *fork_idle(int);
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-struct mm_struct *copy_init_mm(void);
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 extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
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 extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
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 int kernel_wait(pid_t pid, int *stat);
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@@ -109,10 +110,36 @@
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 }
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 extern void __put_task_struct(struct task_struct *t);
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+extern void __put_task_struct_rcu_cb(struct rcu_head *rhp);
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 static inline void put_task_struct(struct task_struct *t)
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 {
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-	if (refcount_dec_and_test(&t->usage))
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+	if (!refcount_dec_and_test(&t->usage))
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+		return;
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+
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+	/*
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+	 * under PREEMPT_RT, we can't call put_task_struct
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+	 * in atomic context because it will indirectly
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+	 * acquire sleeping locks.
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+	 *
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+	 * call_rcu() will schedule delayed_put_task_struct_rcu()
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+	 * to be called in process context.
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+	 *
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+	 * __put_task_struct() is called when
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+	 * refcount_dec_and_test(&t->usage) succeeds.
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+	 *
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+	 * This means that it can't "conflict" with
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+	 * put_task_struct_rcu_user() which abuses ->rcu the same
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+	 * way; rcu_users has a reference so task->usage can't be
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+	 * zero after rcu_users 1 -> 0 transition.
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+	 *
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+	 * delayed_free_task() also uses ->rcu, but it is only called
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+	 * when it fails to fork a process. Therefore, there is no
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+	 * way it can conflict with put_task_struct().
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+	 */
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+	if (IS_ENABLED(CONFIG_PREEMPT_RT) && !preemptible())
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+		call_rcu(&t->rcu, __put_task_struct_rcu_cb);
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+	else
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 		__put_task_struct(t);
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 }
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