From: Jens Axboe axboe@kernel.dk
[ Upstream commit cc440e8738e5c875297ac0e90316745093be7e28 ]
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 axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/sched/task.h | 2 ++ kernel/fork.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 32 insertions(+)
--- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -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; }; @@ -85,6 +86,7 @@ extern void exit_files(struct task_struc extern void exit_itimers(struct task_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); --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1949,6 +1949,8 @@ static __latent_entropy struct task_stru 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 @@ -2416,6 +2418,34 @@ struct mm_struct *copy_init_mm(void) }
/* + * 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. * * It copies the process, and if successful kick-starts