FreeBSD/Linux Kernel Cross Reference
sys/compat/linuxkpi/common/src/linux_kthread.c

     /*-
      * Copyright (c) 2017 Hans Petter Selasky
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice unmodified, this list of conditions, and the following
     *    disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <linux/compat.h>
    #include <linux/kthread.h>
    #include <linux/sched.h>
    #include <linux/wait.h>
    
    #include <sys/bus.h>
    #include <sys/interrupt.h>
    #include <sys/priority.h>
    
    enum {
            KTHREAD_SHOULD_STOP_MASK = (1 << 0),
            KTHREAD_SHOULD_PARK_MASK = (1 << 1),
            KTHREAD_IS_PARKED_MASK = (1 << 2),
    };
    
    bool
    linux_kthread_should_stop_task(struct task_struct *task)
    {
    
            return (atomic_read(&task->kthread_flags) & KTHREAD_SHOULD_STOP_MASK);
    }
    
    bool
    linux_kthread_should_stop(void)
    {
    
            return (atomic_read(&current->kthread_flags) & KTHREAD_SHOULD_STOP_MASK);
    }
    
    int
    linux_kthread_stop(struct task_struct *task)
    {
            int retval;
    
            /*
             * Assume task is still alive else caller should not call
             * kthread_stop():
             */
            atomic_or(KTHREAD_SHOULD_STOP_MASK, &task->kthread_flags);
            kthread_unpark(task);
            wake_up_process(task);
            wait_for_completion(&task->exited);
    
            /*
             * Get return code and free task structure:
             */
            retval = task->task_ret;
            put_task_struct(task);
    
            return (retval);
    }
    
    int
    linux_kthread_park(struct task_struct *task)
    {
    
            atomic_or(KTHREAD_SHOULD_PARK_MASK, &task->kthread_flags);
            wake_up_process(task);
            wait_for_completion(&task->parked);
            return (0);
    }
    
    void
    linux_kthread_parkme(void)
    {
            struct task_struct *task;
    
            task = current;
            set_task_state(task, TASK_PARKED | TASK_UNINTERRUPTIBLE);
            while (linux_kthread_should_park()) {
                   while ((atomic_fetch_or(KTHREAD_IS_PARKED_MASK,
                       &task->kthread_flags) & KTHREAD_IS_PARKED_MASK) == 0)
                           complete(&task->parked);
                   schedule();
                   set_task_state(task, TASK_PARKED | TASK_UNINTERRUPTIBLE);
           }
           atomic_andnot(KTHREAD_IS_PARKED_MASK, &task->kthread_flags);
           set_task_state(task, TASK_RUNNING);
   }
   
   bool
   linux_kthread_should_park(void)
   {
           struct task_struct *task;
   
           task = current;
           return (atomic_read(&task->kthread_flags) & KTHREAD_SHOULD_PARK_MASK);
   }
   
   void
   linux_kthread_unpark(struct task_struct *task)
   {
   
           atomic_andnot(KTHREAD_SHOULD_PARK_MASK, &task->kthread_flags);
           if ((atomic_fetch_andnot(KTHREAD_IS_PARKED_MASK, &task->kthread_flags) &
               KTHREAD_IS_PARKED_MASK) != 0)
                   wake_up_state(task, TASK_PARKED);
   }
   
   struct task_struct *
   linux_kthread_setup_and_run(struct thread *td, linux_task_fn_t *task_fn, void *arg)
   {
           struct task_struct *task;
   
           linux_set_current(td);
   
           task = td->td_lkpi_task;
           task->task_fn = task_fn;
           task->task_data = arg;
   
           thread_lock(td);
           /* make sure the scheduler priority is raised */
           sched_prio(td, PI_SWI(SWI_NET));
           /* put thread into run-queue */
           sched_add(td, SRQ_BORING);
   
           return (task);
   }
   
   void
   linux_kthread_fn(void *arg __unused)
   {
           struct task_struct *task = current;
   
           if (linux_kthread_should_stop_task(task) == 0)
                   task->task_ret = task->task_fn(task->task_data);
   
           if (linux_kthread_should_stop_task(task) != 0) {
                   struct thread *td = curthread;
   
                   /* let kthread_stop() free data */
                   td->td_lkpi_task = NULL;
   
                   /* wakeup kthread_stop() */
                   complete(&task->exited);
           }
           kthread_exit();
   }
   
   void
   lkpi_kthread_work_fn(void *context, int pending __unused)
   {
           struct kthread_work *work = context;
   
           work->func(work);
   }
   
   void
   lkpi_kthread_worker_init_fn(void *context, int pending __unused)
   {
           struct kthread_worker *worker = context;
   
           worker->task = current;
   }

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