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https://github.com/cloud-hypervisor/cloud-hypervisor.git
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virtio-block: Port to EpollHelper
Port virtio-block device to the new EpollHelper. This required moving the queue EventFd ownership to BlockEpollHandler. Signed-off-by: Rob Bradford <robert.bradford@intel.com>
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@ -10,19 +10,18 @@
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use super::Error as DeviceError;
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use super::{
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ActivateError, ActivateResult, DeviceEventT, Queue, VirtioDevice, VirtioDeviceType,
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VirtioInterruptType,
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ActivateError, ActivateResult, EpollHelper, EpollHelperError, EpollHelperHandler, Queue,
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VirtioDevice, VirtioDeviceType, VirtioInterruptType, EPOLL_HELPER_EVENT_LAST,
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};
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use crate::VirtioInterrupt;
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use anyhow::anyhow;
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use block_util::{build_disk_image_id, Request, RequestType, VirtioBlockConfig};
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use libc::EFD_NONBLOCK;
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use std::collections::HashMap;
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use std::fs::File;
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use std::io::{self, Read, Seek, SeekFrom, Write};
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use std::num::Wrapping;
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use std::ops::DerefMut;
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use std::os::unix::io::{AsRawFd, FromRawFd};
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use std::os::unix::io::AsRawFd;
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use std::path::PathBuf;
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use std::result;
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use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
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@ -44,13 +43,7 @@ const SECTOR_SHIFT: u8 = 9;
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pub const SECTOR_SIZE: u64 = (0x01 as u64) << SECTOR_SHIFT;
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// New descriptors are pending on the virtio queue.
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const QUEUE_AVAIL_EVENT: DeviceEventT = 0;
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// The device has been dropped.
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pub const KILL_EVENT: DeviceEventT = 1;
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// Number of DeviceEventT events supported by this implementation.
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pub const BLOCK_EVENTS_COUNT: usize = 2;
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// The device should be paused.
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const PAUSE_EVENT: DeviceEventT = 3;
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const QUEUE_AVAIL_EVENT: u16 = EPOLL_HELPER_EVENT_LAST + 1;
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#[derive(Debug)]
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pub enum Error {
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@ -95,6 +88,7 @@ struct BlockEpollHandler<T: DiskFile> {
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event_idx: bool,
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writeback: Arc<AtomicBool>,
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counters: BlockCounters,
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queue_evt: EventFd,
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}
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impl<T: DiskFile> BlockEpollHandler<T> {
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@ -202,131 +196,57 @@ impl<T: DiskFile> BlockEpollHandler<T> {
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Ok(())
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}
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fn run(
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&mut self,
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queue_evt: EventFd,
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paused: Arc<AtomicBool>,
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) -> result::Result<(), DeviceError> {
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// Create the epoll file descriptor
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let epoll_fd = epoll::create(true).map_err(DeviceError::EpollCreateFd)?;
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// Use 'File' to enforce closing on 'epoll_fd'
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let epoll_file = unsafe { File::from_raw_fd(epoll_fd) };
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fn run(&mut self, paused: Arc<AtomicBool>) -> result::Result<(), EpollHelperError> {
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let mut helper = EpollHelper::new(&self.kill_evt, &self.pause_evt)?;
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helper.add_event(self.queue_evt.as_raw_fd(), QUEUE_AVAIL_EVENT)?;
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helper.run(paused, self)?;
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// Add events
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epoll::ctl(
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epoll_file.as_raw_fd(),
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epoll::ControlOptions::EPOLL_CTL_ADD,
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queue_evt.as_raw_fd(),
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epoll::Event::new(epoll::Events::EPOLLIN, u64::from(QUEUE_AVAIL_EVENT)),
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)
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.map_err(DeviceError::EpollCtl)?;
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epoll::ctl(
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epoll_file.as_raw_fd(),
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epoll::ControlOptions::EPOLL_CTL_ADD,
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self.kill_evt.as_raw_fd(),
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epoll::Event::new(epoll::Events::EPOLLIN, u64::from(KILL_EVENT)),
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)
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.map_err(DeviceError::EpollCtl)?;
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epoll::ctl(
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epoll_file.as_raw_fd(),
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epoll::ControlOptions::EPOLL_CTL_ADD,
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self.pause_evt.as_raw_fd(),
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epoll::Event::new(epoll::Events::EPOLLIN, u64::from(PAUSE_EVENT)),
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)
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.map_err(DeviceError::EpollCtl)?;
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Ok(())
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}
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}
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const EPOLL_EVENTS_LEN: usize = 100;
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let mut events = vec![epoll::Event::new(epoll::Events::empty(), 0); EPOLL_EVENTS_LEN];
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impl<T: DiskFile> EpollHelperHandler for BlockEpollHandler<T> {
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fn handle_event(&mut self, _helper: &mut EpollHelper, event: u16) -> bool {
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match event {
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QUEUE_AVAIL_EVENT => {
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if let Err(e) = self.queue_evt.read() {
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error!("Failed to get queue event: {:?}", e);
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return true;
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} else if self.event_idx {
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// vm-virtio's Queue implementation only checks avail_index
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// once, so to properly support EVENT_IDX we need to keep
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// calling process_queue() until it stops finding new
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// requests on the queue.
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loop {
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if self.process_queue() {
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self.queue.update_avail_event(&self.mem.memory());
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// Before jumping into the epoll loop, check if the device is expected
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// to be in a paused state. This is helpful for the restore code path
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// as the device thread should not start processing anything before the
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// device has been resumed.
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while paused.load(Ordering::SeqCst) {
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thread::park();
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}
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'epoll: loop {
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let num_events = match epoll::wait(epoll_file.as_raw_fd(), -1, &mut events[..]) {
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Ok(res) => res,
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Err(e) => {
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if e.kind() == io::ErrorKind::Interrupted {
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// It's well defined from the epoll_wait() syscall
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// documentation that the epoll loop can be interrupted
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// before any of the requested events occurred or the
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// timeout expired. In both those cases, epoll_wait()
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// returns an error of type EINTR, but this should not
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// be considered as a regular error. Instead it is more
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// appropriate to retry, by calling into epoll_wait().
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continue;
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}
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return Err(DeviceError::EpollWait(e));
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}
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};
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for event in events.iter().take(num_events) {
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let ev_type = event.data as u16;
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match ev_type {
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QUEUE_AVAIL_EVENT => {
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if let Err(e) = queue_evt.read() {
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error!("Failed to get queue event: {:?}", e);
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break 'epoll;
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} else if self.event_idx {
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// vm-virtio's Queue implementation only checks avail_index
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// once, so to properly support EVENT_IDX we need to keep
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// calling process_queue() until it stops finding new
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// requests on the queue.
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loop {
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if self.process_queue() {
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self.queue.update_avail_event(&self.mem.memory());
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if self.queue.needs_notification(
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&self.mem.memory(),
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self.queue.next_used,
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) {
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if let Err(e) = self.signal_used_queue() {
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error!("Failed to signal used queue: {:?}", e);
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break 'epoll;
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}
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}
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} else {
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break;
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if self
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.queue
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.needs_notification(&self.mem.memory(), self.queue.next_used)
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{
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if let Err(e) = self.signal_used_queue() {
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error!("Failed to signal used queue: {:?}", e);
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return true;
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}
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}
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} else if self.process_queue() {
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if let Err(e) = self.signal_used_queue() {
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error!("Failed to signal used queue: {:?}", e);
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break 'epoll;
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}
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} else {
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break;
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}
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}
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KILL_EVENT => {
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debug!("KILL_EVENT received, stopping epoll loop");
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break 'epoll;
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}
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PAUSE_EVENT => {
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debug!("PAUSE_EVENT received, pausing virtio-block epoll loop");
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// We loop here to handle spurious park() returns.
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// Until we have not resumed, the paused boolean will
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// be true.
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while paused.load(Ordering::SeqCst) {
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thread::park();
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}
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// Drain pause event after the device has been resumed.
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// This ensures the pause event has been seen by each
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// and every thread related to this virtio device.
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let _ = self.pause_evt.read();
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}
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_ => {
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error!("Unknown event for virtio-block");
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} else if self.process_queue() {
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if let Err(e) = self.signal_used_queue() {
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error!("Failed to signal used queue: {:?}", e);
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return true;
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}
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}
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}
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_ => {
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error!("Unexpected event: {}", event);
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return true;
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}
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}
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Ok(())
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false
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}
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}
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@ -342,7 +262,7 @@ pub struct Block<T: DiskFile> {
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config: VirtioBlockConfig,
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queue_evts: Option<Vec<EventFd>>,
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interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
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epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), DeviceError>>>>,
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epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), EpollHelperError>>>>,
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pause_evt: Option<EventFd>,
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paused: Arc<AtomicBool>,
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queue_size: Vec<u16>,
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@ -588,6 +508,7 @@ impl<T: 'static + DiskFile + Send> VirtioDevice for Block<T> {
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let mut epoll_threads = Vec::new();
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for _ in 0..self.queue_size.len() {
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let queue_evt = queue_evts.remove(0);
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let mut handler = BlockEpollHandler {
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queue: queues.remove(0),
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mem: mem.clone(),
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@ -600,15 +521,15 @@ impl<T: 'static + DiskFile + Send> VirtioDevice for Block<T> {
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event_idx,
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writeback: self.writeback.clone(),
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counters: self.counters.clone(),
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queue_evt,
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};
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handler.queue.set_event_idx(event_idx);
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let queue_evt = queue_evts.remove(0);
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let paused = self.paused.clone();
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thread::Builder::new()
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.name("virtio_blk".to_string())
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.spawn(move || handler.run(queue_evt, paused))
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.spawn(move || handler.run(paused))
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.map(|thread| epoll_threads.push(thread))
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.map_err(|e| {
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error!("failed to clone the virtio-blk epoll thread: {}", e);
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