From cc440e8738e5c875297ac0e90316745093be7e28 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 4 Mar 2021 12:21:05 -0700 Subject: 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: Jens Axboe --- kernel/fork.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index d66cd1014211..d3171e8e88e5 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -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. * -- cgit v1.2.3