From dd6663096680b8cfb77b707b54fc8a04f85f1a2f Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 22 Nov 2021 10:27:36 -0600 Subject: [PATCH] exit: Implement kthread_exit [ Upstream commit bbda86e988d4c124e4cfa816291cbd583ae8bfb1 ] 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: "Eric W. Biederman" Stable-dep-of: ca3574bd653a ("exit: Rename module_put_and_exit to module_put_and_kthread_exit") Signed-off-by: Chuck Lever --- include/linux/kthread.h | 1 + kernel/kthread.c | 23 +++++++++++++++++++---- tools/objtool/check.c | 1 + 3 files changed, 21 insertions(+), 4 deletions(-) diff --git a/include/linux/kthread.h b/include/linux/kthread.h index db47aae7c481..8e21bd13c36d 100644 --- a/include/linux/kthread.h +++ b/include/linux/kthread.h @@ -95,6 +95,7 @@ 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; diff --git a/kernel/kthread.c b/kernel/kthread.c index e319a1b62586..4cc6897b7ca4 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -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) { /* Copy data: it's on kthread's stack */ @@ -285,13 +300,13 @@ 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; @@ -318,7 +333,7 @@ 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 */ @@ -628,7 +643,7 @@ 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() diff --git a/tools/objtool/check.c b/tools/objtool/check.c index c3bb96e5bfa6..f066837d8e1a 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -169,6 +169,7 @@ 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",