Replace mpsc with crossbeam-channel

On Apple Silicon, we were hitting a concurrency error that manifest
with recv() panicking like this:

thread '<unnamed>' panicked at 'internal error: entered unreachable
code'

Seems to be a known issue
rust-lang/rust#39364

Follow the recommendation on the thread, and switch from mpsc (which
seems its going to be retired) to crossbeam-channel.

Signed-off-by: Sergio Lopez <slp@sinrega.org>

src/devices/Cargo.toml

@@ -9,6 +9,7 @@ amd-sev = []
 
 [dependencies]
 bitflags = "1.2.0"
+crossbeam-channel = "0.5"
 env_logger = "0.9.0"
 libc = ">=0.2.39"
 log = "0.4.0"

src/devices/src/legacy/gic.rs

@@ -1,10 +1,10 @@
 // Copyright 2021 Red Hat, Inc.
 // SPDX-License-Identifier: Apache-2.0
 
+use crossbeam_channel::Sender;
 use std::collections::btree_map::Entry;
 use std::collections::{BTreeMap, VecDeque};
 use std::convert::TryInto;
-use std::sync::mpsc::Sender;
 
 use arch::aarch64::gicv2::GICv2;
 use arch::aarch64::layout::GTIMER_VIRT;

src/devices/src/virtio/vsock/muxer.rs

@@ -1,7 +1,6 @@
 use std::collections::HashMap;
 use std::os::unix::io::RawFd;
 use std::sync::atomic::{AtomicUsize, Ordering};
-use std::sync::mpsc::{channel, Sender};
 use std::sync::{Arc, Mutex, RwLock};
 
 use super::super::super::legacy::Gic;
@@ -17,6 +16,7 @@ use super::reaper::ReaperThread;
 use super::tcp::TcpProxy;
 use super::udp::UdpProxy;
 use super::VsockError;
+use crossbeam_channel::{unbounded, Sender};
 use utils::epoll::{ControlOperation, Epoll, EpollEvent, EventSet};
 use utils::eventfd::EventFd;
 use vm_memory::GuestMemoryMmap;
@@ -146,7 +146,7 @@ impl VsockMuxer {
         self.intc = intc.clone();
         self.irq_line = irq_line;
 
-        let (sender, receiver) = channel();
+        let (sender, receiver) = unbounded();
 
         let thread = MuxerThread::new(
             self.cid,

src/devices/src/virtio/vsock/muxer_thread.rs

@@ -1,6 +1,5 @@
 use std::os::unix::io::RawFd;
 use std::sync::atomic::{AtomicUsize, Ordering};
-use std::sync::mpsc::Sender;
 use std::sync::{Arc, Mutex};
 use std::thread;
 
@@ -12,6 +11,7 @@ use super::muxer_rxq::MuxerRxQ;
 use super::proxy::{ProxyRemoval, ProxyUpdate};
 use super::tcp::TcpProxy;
 
+use crossbeam_channel::Sender;
 use rand::{rngs::ThreadRng, thread_rng, Rng};
 use utils::epoll::{ControlOperation, Epoll, EpollEvent, EventSet};
 use utils::eventfd::EventFd;

src/devices/src/virtio/vsock/reaper.rs

@@ -1,10 +1,10 @@
 use std::collections::HashMap;
-use std::sync::mpsc::Receiver;
 use std::sync::{Arc, Mutex, RwLock};
 use std::thread;
 use std::time::{Duration, Instant};
 
 use super::proxy::Proxy;
+use crossbeam_channel::Receiver;
 
 pub type ProxyMap = Arc<RwLock<HashMap<u64, Mutex<Box<dyn Proxy>>>>>;
 const TIMEOUT: Duration = Duration::new(5, 0);

src/vmm/Cargo.toml

@@ -8,6 +8,7 @@ edition = "2021"
 amd-sev = [ "codicon", "kbs-types", "procfs", "serde", "serde_json", "sev", "curl" ]
 
 [dependencies]
+crossbeam-channel = "0.5"
 env_logger = "0.9.0"
 libc = ">=0.2.39"
 log = "0.4.0"

src/vmm/src/builder.rs

@@ -3,11 +3,11 @@
 
 //! Enables pre-boot setup, instantiation and booting of a Firecracker VMM.
 
+#[cfg(target_os = "macos")]
+use crossbeam_channel::unbounded;
 use std::fmt::{Display, Formatter};
 use std::io;
 use std::os::unix::io::{AsRawFd, RawFd};
-#[cfg(target_os = "macos")]
-use std::sync::mpsc::channel;
 use std::sync::{Arc, Mutex};
 
 use super::{Error, Vmm};
@@ -930,7 +930,7 @@ fn create_vcpus_aarch64(
 
     for cpu_index in 0..vcpu_config.vcpu_count {
         let boot_receiver = if cpu_index != 0 {
-            let (boot_sender, boot_receiver) = channel();
+            let (boot_sender, boot_receiver) = unbounded();
             boot_senders.push(boot_sender);
             Some(boot_receiver)
         } else {

src/vmm/src/linux/vstate.rs

@@ -5,13 +5,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the THIRD-PARTY file.
 
+use crossbeam_channel::{unbounded, Receiver, Sender, TryRecvError};
 use libc::{c_int, c_void, siginfo_t};
 use std::cell::Cell;
 use std::fmt::{Display, Formatter};
 use std::io;
 use std::result;
 use std::sync::atomic::{fence, Ordering};
-use std::sync::mpsc::{channel, Receiver, Sender, TryRecvError};
 #[cfg(not(test))]
 use std::sync::Barrier;
 use std::thread;
@@ -815,8 +815,8 @@ impl Vcpu {
         create_ts: TimestampUs,
     ) -> Result<Self> {
         let kvm_vcpu = vm_fd.create_vcpu(id as u64).map_err(Error::VcpuFd)?;
-        let (event_sender, event_receiver) = channel();
-        let (response_sender, response_receiver) = channel();
+        let (event_sender, event_receiver) = unbounded();
+        let (response_sender, response_receiver) = unbounded();
 
         // Initially the cpuid per vCPU is the one supported by this VM.
         Ok(Vcpu {
@@ -851,8 +851,8 @@ impl Vcpu {
         create_ts: TimestampUs,
     ) -> Result<Self> {
         let kvm_vcpu = vm_fd.create_vcpu(id as u64).map_err(Error::VcpuFd)?;
-        let (event_sender, event_receiver) = channel();
-        let (response_sender, response_receiver) = channel();
+        let (event_sender, event_receiver) = unbounded();
+        let (response_sender, response_receiver) = unbounded();
 
         Ok(Vcpu {
             fd: kvm_vcpu,
@@ -973,7 +973,7 @@ impl Vcpu {
     pub fn start_threaded(mut self) -> Result<VcpuHandle> {
         let event_sender = self.event_sender.take().unwrap();
         let response_receiver = self.response_receiver.take().unwrap();
-        let (init_tls_sender, init_tls_receiver) = channel();
+        let (init_tls_sender, init_tls_receiver) = unbounded();
         let vcpu_thread = thread::Builder::new()
             .name(format!("fc_vcpu {}", self.cpu_index()))
             .spawn(move || {
@@ -1420,6 +1420,7 @@ enum VcpuEmulation {
 
 #[cfg(test)]
 mod tests {
+    use crossbeam_channel::unbounded;
     use std::fs::File;
     use std::sync::{Arc, Barrier};
 
@@ -1434,7 +1435,7 @@ mod tests {
             // Make sure the Vcpu is out of KVM_RUN.
             self.send_event(VcpuEvent::Pause).unwrap();
             // Close the original channel so that the Vcpu thread errors and goes to exit state.
-            let (event_sender, _event_receiver) = channel();
+            let (event_sender, _event_receiver) = unbounded();
             self.event_sender = event_sender;
             // Wait for the Vcpu thread to finish execution
             self.vcpu_thread.take().unwrap().join().unwrap();

src/vmm/src/macos/vstate.rs

@@ -9,7 +9,6 @@ use std::cell::Cell;
 use std::fmt::{Display, Formatter};
 use std::io;
 use std::result;
-use std::sync::mpsc::{channel, Receiver, RecvTimeoutError, Sender};
 #[cfg(not(test))]
 use std::sync::{Arc, Mutex};
 use std::thread;
@@ -21,6 +20,7 @@ use crate::vmm_config::machine_config::CpuFeaturesTemplate;
 
 use arch;
 use arch::aarch64::gic::GICDevice;
+use crossbeam_channel::{unbounded, Receiver, RecvTimeoutError, Sender};
 use devices::legacy::Gic;
 use hvf::{HvfVcpu, HvfVm, VcpuExit};
 use utils::eventfd::EventFd;
@@ -267,8 +267,8 @@ impl Vcpu {
         _create_ts: TimestampUs,
         intc: Arc<Mutex<Gic>>,
     ) -> Result<Self> {
-        let (event_sender, event_receiver) = channel();
-        let (response_sender, response_receiver) = channel();
+        let (event_sender, event_receiver) = unbounded();
+        let (response_sender, response_receiver) = unbounded();
 
         Ok(Vcpu {
             id,
@@ -325,7 +325,7 @@ impl Vcpu {
     pub fn start_threaded(mut self) -> Result<VcpuHandle> {
         let event_sender = self.event_sender.take().unwrap();
         let response_receiver = self.response_receiver.take().unwrap();
-        let (init_tls_sender, init_tls_receiver) = channel();
+        let (init_tls_sender, init_tls_receiver) = unbounded();
 
         let vcpu_thread = thread::Builder::new()
             .name(format!("fc_vcpu {}", self.cpu_index()))
@@ -441,7 +441,7 @@ impl Vcpu {
         let mut hvf_vcpu = HvfVcpu::new().expect("Can't create HVF vCPU");
         let hvf_vcpuid = hvf_vcpu.id();
 
-        let (wfe_sender, wfe_receiver) = channel();
+        let (wfe_sender, wfe_receiver) = unbounded();
         self.intc
             .lock()
             .unwrap()
@@ -599,11 +599,11 @@ enum VcpuEmulation {
 
 #[cfg(test)]
 mod tests {
+    #[cfg(target_arch = "x86_64")]
+    use crossbeam_channel::{unbounded, RecvTimeoutError};
     use std::fs::File;
     #[cfg(target_arch = "x86_64")]
     use std::os::unix::io::AsRawFd;
-    #[cfg(target_arch = "x86_64")]
-    use std::sync::mpsc;
     use std::sync::{Arc, Barrier};
     #[cfg(target_arch = "x86_64")]
     use std::time::Duration;
@@ -619,7 +619,7 @@ mod tests {
             // Make sure the Vcpu is out of KVM_RUN.
             self.send_event(VcpuEvent::Pause).unwrap();
             // Close the original channel so that the Vcpu thread errors and goes to exit state.
-            let (event_sender, _event_receiver) = channel();
+            let (event_sender, _event_receiver) = unbounded();
             self.event_sender = event_sender;
             // Wait for the Vcpu thread to finish execution
             self.vcpu_thread.take().unwrap().join().unwrap();
@@ -933,7 +933,7 @@ mod tests {
             handle
                 .response_receiver()
                 .recv_timeout(Duration::from_millis(100)),
-            Err(mpsc::RecvTimeoutError::Timeout)
+            Err(RecvTimeoutError::Timeout)
         );
     }