github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/kernel/task_work.go (about)

     1  // Copyright 2020 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package kernel
    16  
    17  import "sync/atomic"
    18  
    19  // TaskWorker is a deferred task.
    20  //
    21  // This must be savable.
    22  type TaskWorker interface {
    23  	// TaskWork will be executed prior to returning to user space. Note that
    24  	// TaskWork may call RegisterWork again, but this will not be executed until
    25  	// the next return to user space, unlike in Linux. This effectively allows
    26  	// registration of indefinite user return hooks, but not by default.
    27  	TaskWork(t *Task)
    28  }
    29  
    30  // RegisterWork can be used to register additional task work that will be
    31  // performed prior to returning to user space. See TaskWorker.TaskWork for
    32  // semantics regarding registration.
    33  func (t *Task) RegisterWork(work TaskWorker) {
    34  	t.taskWorkMu.Lock()
    35  	defer t.taskWorkMu.Unlock()
    36  	atomic.AddInt32(&t.taskWorkCount, 1)
    37  	t.taskWork = append(t.taskWork, work)
    38  }