From a46237106cb48e7f4a1bf458d227981f291d59f0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=BD=D0=B0=D0=B1?= <nabijaczleweli@nabijaczleweli.xyz>
Date: Wed, 19 Jan 2022 21:33:50 +0100
Subject: [PATCH] Linux 5.17 compat: dequeue_signal() takes a 4th argument
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Linux 5.17's dequeue_signal() takes an additional enum pid_type *
output argument

Upstream commit 5768d8906bc23d512b1a736c1e198aa833a6daa4
("signal: Requeue signals in the appropriate queue")

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12989
---
 config/kernel-kthread.m4         | 45 ++++++++++++++++++++++++++++++--
 module/os/linux/spl/spl-thread.c |  5 ++++
 2 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/config/kernel-kthread.m4 b/config/kernel-kthread.m4
index 6459f831e799..f5b824d7947a 100644
--- a/config/kernel-kthread.m4
+++ b/config/kernel-kthread.m4
@@ -1,4 +1,4 @@
-AC_DEFUN([ZFS_AC_KERNEL_KTHREAD], [
+AC_DEFUN([ZFS_AC_KERNEL_KTHREAD_COMPLETE_AND_EXIT], [
 	dnl #
 	dnl # 5.17 API,
 	dnl # cead18552660702a4a46f58e65188fe5f36e9dfe ("exit: Rename complete_and_exit to kthread_complete_and_exit")
@@ -15,7 +15,24 @@ AC_DEFUN([ZFS_AC_KERNEL_KTHREAD], [
 	])
 ])
 
-AC_DEFUN([ZFS_AC_KERNEL_SRC_KTHREAD], [
+AC_DEFUN([ZFS_AC_KERNEL_KTHREAD_DEQUEUE_SIGNAL_4ARG], [
+	dnl #
+	dnl # 5.17 API: enum pid_type * as new 4th dequeue_signal() argument,
+	dnl # 5768d8906bc23d512b1a736c1e198aa833a6daa4 ("signal: Requeue signals in the appropriate queue")
+	dnl #
+	dnl # int dequeue_signal(struct task_struct *task, sigset_t *mask, kernel_siginfo_t *info);
+	dnl # int dequeue_signal(struct task_struct *task, sigset_t *mask, kernel_siginfo_t *info, enum pid_type *type);
+	dnl #
+	AC_MSG_CHECKING([whether dequeue_signal() takes 4 arguments])
+	ZFS_LINUX_TEST_RESULT([kthread_dequeue_signal], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_DEQUEUE_SIGNAL_4ARG, 1, [dequeue_signal() takes 4 arguments])
+	], [
+		AC_MSG_RESULT(no)
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_SRC_KTHREAD_COMPLETE_AND_EXIT], [
 	ZFS_LINUX_TEST_SRC([kthread_complete_and_exit], [
 		#include <linux/kthread.h>
 	], [
@@ -25,3 +42,27 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_KTHREAD], [
 		kthread_complete_and_exit(completion, code);
 	])
 ])
+
+AC_DEFUN([ZFS_AC_KERNEL_SRC_KTHREAD_DEQUEUE_SIGNAL_4ARG], [
+	ZFS_LINUX_TEST_SRC([kthread_dequeue_signal], [
+		#include <linux/sched/signal.h>
+	], [
+		struct task_struct *task = NULL;
+		sigset_t *mask = NULL;
+		kernel_siginfo_t *info = NULL;
+		enum pid_type *type = NULL;
+		int error __attribute__ ((unused));
+
+		error = dequeue_signal(task, mask, info, type);
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_KTHREAD], [
+	ZFS_AC_KERNEL_KTHREAD_COMPLETE_AND_EXIT
+	ZFS_AC_KERNEL_KTHREAD_DEQUEUE_SIGNAL_4ARG
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_SRC_KTHREAD], [
+	ZFS_AC_KERNEL_SRC_KTHREAD_COMPLETE_AND_EXIT
+	ZFS_AC_KERNEL_SRC_KTHREAD_DEQUEUE_SIGNAL_4ARG
+])
diff --git a/module/os/linux/spl/spl-thread.c b/module/os/linux/spl/spl-thread.c
index 0ba4c18c1659..16d2ca1b133b 100644
--- a/module/os/linux/spl/spl-thread.c
+++ b/module/os/linux/spl/spl-thread.c
@@ -188,7 +188,12 @@ issig(int why)
 
 	spin_lock_irq(&task->sighand->siglock);
 	int ret;
+#ifdef HAVE_DEQUEUE_SIGNAL_4ARG
+	enum pid_type __type;
+	if ((ret = dequeue_signal(task, &set, &__info, &__type)) != 0) {
+#else
 	if ((ret = dequeue_signal(task, &set, &__info)) != 0) {
+#endif
 #ifdef HAVE_SIGNAL_STOP
 		spin_unlock_irq(&task->sighand->siglock);
 		kernel_signal_stop();