5.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
[ 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" <ebiederm@xxxxxxxxxxxx>
Stable-dep-of: ca3574bd653a ("exit: Rename module_put_and_exit to module_put_and_kthread_exit")
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 2484ed97e72f5..9dae77a97a033 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -68,6 +68,7 @@ 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 508fe52782857..9d6cc9c15a55e 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -262,6 +262,21 @@ 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 */
@@ -279,13 +294,13 @@ 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;
@@ -312,7 +327,7 @@ static int kthread(void *_create)
__kthread_parkme(self);
ret = threadfn(data);
}
- do_exit(ret);
+ kthread_exit(ret);
}
/* called from do_fork() to get node information for about to be created task */
@@ -621,7 +636,7 @@ 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 059b78d08f7af..6afa1f8ca1614 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -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",
--
2.43.0
