[PATCH V3 1/9] fork: Make IO worker options flag based

Mike Christie
2021-10-04T19:21:20Z

This patchset adds a couple new options to kernel_clone_args for IO thread
like/related users. Instead of adding new fields to kernel_clone_args for
each option, this moves us to a flags based approach by first converting
io_thread.

Signed-off-by: Mike Christie <michael.christie at oracle.com>
Suggested-by: Christian Brauner <christian.brauner at ubuntu.com>
Acked-by: Christian Brauner <christian.brauner at ubuntu.com>
---
 include/linux/sched/task.h | 4 +++-
 kernel/fork.c              | 4 ++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index ef02be869cf2..48417c735438 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -18,8 +18,11 @@ struct css_set;
 /* All the bits taken by the old clone syscall. */
 #define CLONE_LEGACY_FLAGS 0xffffffffULL

+#define KERN_WORKER_IO		BIT(0)
+
 struct kernel_clone_args {
 	u64 flags;
+	u32 worker_flags;
 	int __user *pidfd;
 	int __user *child_tid;
 	int __user *parent_tid;
@@ -31,7 +34,6 @@ struct kernel_clone_args {
 	/* Number of elements in *set_tid */
 	size_t set_tid_size;
 	int cgroup;
-	int io_thread;
 	struct cgroup *cgrp;
 	struct css_set *cset;
 };
diff --git a/kernel/fork.c b/kernel/fork.c
index 38681ad44c76..3988106e9609 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2026,7 +2026,7 @@ static __latent_entropy struct task_struct *copy_process(
 	p = dup_task_struct(current, node);
 	if (!p)
 		goto fork_out;
-	if (args->io_thread) {
+	if (args->worker_flags & KERN_WORKER_IO) {
 		/*
 		 * Mark us an IO worker, and block any signal that isn't
 		 * fatal or STOP
@@ -2526,7 +2526,7 @@ struct task_struct *create_io_thread(int (*fn)(void *),
void *arg, int node)
 		.exit_signal	= (lower_32_bits(flags) & CSIGNAL),
 		.stack		= (unsigned long)fn,
 		.stack_size	= (unsigned long)arg,
-		.io_thread	= 1,
+		.worker_flags	= KERN_WORKER_IO,
 	};

 	return copy_process(NULL, 0, node, &args);
--
2.25.1