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// Copyright 2023 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package sysmsg
import (
"syscall"
"unsafe"
"golang.org/x/sys/unix"
"gvisor.dev/gvisor/pkg/abi/linux"
)
// SleepOnState makes the caller sleep on the ThreadContext.State futex.
func (c *ThreadContext) SleepOnState(curState ContextState, timeout *unix.Timespec) syscall.Errno {
_, _, errno := unix.Syscall6(unix.SYS_FUTEX, uintptr(unsafe.Pointer(&c.State)),
linux.FUTEX_WAIT, uintptr(curState), uintptr(unsafe.Pointer(timeout)), 0, 0)
if errno == unix.EAGAIN || errno == unix.EINTR {
errno = 0
}
return errno
}
// WakeSysmsgThread calls futex wake on Sysmsg.State.
func (m *Msg) WakeSysmsgThread() (bool, syscall.Errno) {
if !m.State.CompareAndSwap(ThreadStateAsleep, ThreadStatePrep) {
return false, 0
}
_, _, e := unix.RawSyscall6(unix.SYS_FUTEX, uintptr(unsafe.Pointer(&m.State)), linux.FUTEX_WAKE, 1, 0, 0, 0)
return true, e
}
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