Commit cc440e87 authored by Jens Axboe's avatar Jens Axboe
Browse files

kernel: provide create_io_thread() helper 



Provide a generic helper for setting up an io_uring worker. Returns a
task_struct so that the caller can do whatever setup is needed, then call
wake_up_new_task() to kick it into gear.

Add a kernel_clone_args member, io_thread, which tells copy_process() to
mark the task with PF_IO_WORKER.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent dd59a3d5

include/linux/sched/task.h

+2 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 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;

};
@@ -82,6 +83,7 @@ extern void exit_files(struct task_struct *); 
extern void exit_itimers(struct signal_struct *);



extern pid_t kernel_clone(struct kernel_clone_args *kargs);

struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);

struct task_struct *fork_idle(int);

struct mm_struct *copy_init_mm(void);

extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);

kernel/fork.c

+30 −0
Original line number Diff line number Diff line
@@ -1940,6 +1940,8 @@ static __latent_entropy struct task_struct *copy_process( 
	p = dup_task_struct(current, node);

	if (!p)

		goto fork_out;

	if (args->io_thread)

		p->flags |= PF_IO_WORKER;



	/*

	 * This _must_ happen before we call free_task(), i.e. before we jump
@@ -2410,6 +2412,34 @@ struct mm_struct *copy_init_mm(void) 
	return dup_mm(NULL, &init_mm);

}



/*

 * This is like kernel_clone(), but shaved down and tailored to just

 * creating io_uring workers. It returns a created task, or an error pointer.

 * The returned task is inactive, and the caller must fire it up through

 * wake_up_new_task(p). All signals are blocked in the created task.

 */

struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)

{

	unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|

				CLONE_IO;

	struct kernel_clone_args args = {

		.flags		= ((lower_32_bits(flags) | CLONE_VM |

				    CLONE_UNTRACED) & ~CSIGNAL),

		.exit_signal	= (lower_32_bits(flags) & CSIGNAL),

		.stack		= (unsigned long)fn,

		.stack_size	= (unsigned long)arg,

		.io_thread	= 1,

	};

	struct task_struct *tsk;



	tsk = copy_process(NULL, 0, node, &args);

	if (!IS_ERR(tsk)) {

		sigfillset(&tsk->blocked);

		sigdelsetmask(&tsk->blocked, sigmask(SIGKILL));

	}

	return tsk;

}



/*

 *  Ok, this is the main fork-routine.

 *