Commit bbda86e9 authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

exit: Implement kthread_exit 



The way the per task_struct exit_code is used by kernel threads is not
quite compatible how it is used by userspace applications.  The low
byte of the userspace exit_code value encodes the exit signal.  While
kthreads just use the value as an int holding ordinary kernel function
exit status like -EPERM.

Add kthread_exit to clearly separate the two kinds of uses.

Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent eb55e716

include/linux/kthread.h

+1 −0
Original line number Diff line number Diff line
@@ -70,6 +70,7 @@ void *kthread_probe_data(struct task_struct *k); 
int kthread_park(struct task_struct *k);

void kthread_unpark(struct task_struct *k);

void kthread_parkme(void);

void kthread_exit(long result) __noreturn;



int kthreadd(void *unused);

extern struct task_struct *kthreadd_task;

kernel/kthread.c

+19 −4
Original line number Diff line number Diff line
@@ -268,6 +268,21 @@ void kthread_parkme(void) 
}

EXPORT_SYMBOL_GPL(kthread_parkme);



/**

 * kthread_exit - Cause the current kthread return @result to kthread_stop().

 * @result: The integer value to return to kthread_stop().

 *

 * While kthread_exit can be called directly, it exists so that

 * functions which do some additional work in non-modular code such as

 * module_put_and_kthread_exit can be implemented.

 *

 * Does not return.

 */

void __noreturn kthread_exit(long result)

{

	do_exit(result);

}



static int kthread(void *_create)

{

	static const struct sched_param param = { .sched_priority = 0 };
@@ -286,13 +301,13 @@ static int kthread(void *_create) 
	done = xchg(&create->done, NULL);

	if (!done) {

		kfree(create);

		do_exit(-EINTR);

		kthread_exit(-EINTR);

	}



	if (!self) {

		create->result = ERR_PTR(-ENOMEM);

		complete(done);

		do_exit(-ENOMEM);

		kthread_exit(-ENOMEM);

	}



	self->threadfn = threadfn;
@@ -326,7 +341,7 @@ static int kthread(void *_create) 
		__kthread_parkme(self);

		ret = threadfn(data);

	}

	do_exit(ret);

	kthread_exit(ret);

}



/* called from kernel_clone() to get node information for about to be created task */
@@ -627,7 +642,7 @@ EXPORT_SYMBOL_GPL(kthread_park); 
 * instead of calling wake_up_process(): the thread will exit without

 * calling threadfn().

 *

 * If threadfn() may call do_exit() itself, the caller must ensure

 * If threadfn() may call kthread_exit() itself, the caller must ensure

 * task_struct can't go away.

 *

 * Returns the result of threadfn(), or %-EINTR if wake_up_process()

tools/objtool/check.c

+1 −0
Original line number Diff line number Diff line
@@ -168,6 +168,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, 
		"panic",

		"do_exit",

		"do_task_dead",

		"kthread_exit",

		"make_task_dead",

		"__module_put_and_exit",

		"complete_and_exit",