[PATCH V6 01/10] fork: Make IO worker options flag based

Mike Christie
2021-11-29T19:49:48Z

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@oracle.com>
Suggested-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
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 058d7f371e25..65d5ec3a8a04 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 USER_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 3244cc56b697..6effd839d566 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2023,7 +2023,7 @@ 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 & USER_WORKER_IO) {
/*
* Mark us an IO worker, and block any signal that isn't
* fatal or STOP
@@ -2524,7 +2524,7 @@ 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 = USER_WORKER_IO,
};

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