diff mbox series

[v11,1/8] fork: Make IO worker options flag based

Message ID 20230202232517.8695-2-michael.christie@oracle.com
State New
Headers
Series Use copy_process in vhost layer |

Commit Message

Mike Christie Feb. 2, 2023, 11:25 p.m. UTC 
  This patchset adds a couple new options to kernel_clone_args for the vhost
layer which is going to work like PF_IO_WORKER but will differ enough that
we will need to add several fields to kernel_clone_args. This patch moves
us to a flags based approach for these types of users.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Suggested-by: Christian Brauner <brauner@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/linux/sched/task.h | 4 +++-
 kernel/fork.c              | 4 ++--
 2 files changed, 5 insertions(+), 3 deletions(-)

Comments

Linus Torvalds Feb. 3, 2023, 12:14 a.m. UTC | #1 
On Thu, Feb 2, 2023 at 3:25 PM Mike Christie
<michael.christie@oracle.com> wrote:
>
>  struct kernel_clone_args {
>         u64 flags;
> +       u32 worker_flags;
>         int __user *pidfd;
>         int __user *child_tid;
>         int __user *parent_tid;

Minor nit: please put this next to "exit_signal".

As it is, you've put a new 32-bit field in between two 64-bit fields
and are generating extra pointless padding.

We have that padding by "exit_signal" already, so let's just use it.

Also, I like moving those flags to a "flags" field, but can we please
make it consistent? We have that "args->kthread" field too, which is
100% analogous to args->io_thread.

So don't make a bit field for io_thread, and then not do the same for kthread.

Finally, why isn't this all just a bitfield - every single case would
seem to prefer something like

     if (args->user_worker) ..

instead of

    if (args->worker_flags & USER_WORKER)

which would seem to make everything simpler still?

            Linus
diff mbox series

Patch

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 357e0068497c..a759ce5aa603 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;
 	int kthread;
 	int idle;
 	int (*fn)(void *);
diff --git a/kernel/fork.c b/kernel/fork.c
index 9f7fe3541897..b030aefba26c 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2100,7 +2100,7 @@  static __latent_entropy struct task_struct *copy_process(
 	p->flags &= ~PF_KTHREAD;
 	if (args->kthread)
 		p->flags |= PF_KTHREAD;
-	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
@@ -2623,7 +2623,7 @@  struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
 		.exit_signal	= (lower_32_bits(flags) & CSIGNAL),
 		.fn		= fn,
 		.fn_arg		= arg,
-		.io_thread	= 1,
+		.worker_flags	= USER_WORKER_IO,
 	};
 
 	return copy_process(NULL, 0, node, &args);