interrupt: Make notifier function return Option<EventFd>

In anticipation for supporting the notifier function for the legacy
interrupt source group, we need this function to return an EventFd
instead of a reference to this same EventFd.

The reason is we can't return a reference when there's an Arc<Mutex<>>
involved in the call chain.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

devices/src/legacy/rtc_pl031.rs

@@ -476,8 +476,8 @@ mod tests {
             Ok(())
         }
 
-        fn notifier(&self, _index: InterruptIndex) -> Option<&EventFd> {
-            Some(&self.event_fd)
+        fn notifier(&self, _index: InterruptIndex) -> Option<EventFd> {
+            Some(self.event_fd.try_clone().unwrap())
         }
     }
 

pci/src/vfio.rs

@@ -429,7 +429,7 @@ impl VfioPciDevice {
         match self.interrupt.update_msi(offset, data) {
             Some(InterruptUpdateAction::EnableMsi) => {
                 if let Some(msi) = &self.interrupt.msi {
-                    let mut irq_fds: Vec<&EventFd> = Vec::new();
+                    let mut irq_fds: Vec<EventFd> = Vec::new();
                     for i in 0..msi.cfg.num_enabled_vectors() {
                         if let Some(eventfd) =
                             msi.interrupt_source_group.notifier(i as InterruptIndex)
@@ -440,7 +440,7 @@ impl VfioPciDevice {
                         }
                     }
 
-                    if let Err(e) = self.device.enable_msi(irq_fds) {
+                    if let Err(e) = self.device.enable_msi(irq_fds.iter().collect()) {
                         warn!("Could not enable MSI: {}", e);
                     }
                 }
@@ -460,7 +460,7 @@ impl VfioPciDevice {
         match self.interrupt.update_msix(offset, data) {
             Some(InterruptUpdateAction::EnableMsix) => {
                 if let Some(msix) = &self.interrupt.msix {
-                    let mut irq_fds: Vec<&EventFd> = Vec::new();
+                    let mut irq_fds: Vec<EventFd> = Vec::new();
                     for i in 0..msix.bar.table_entries.len() {
                         if let Some(eventfd) =
                             msix.interrupt_source_group.notifier(i as InterruptIndex)
@@ -471,7 +471,7 @@ impl VfioPciDevice {
                         }
                     }
 
-                    if let Err(e) = self.device.enable_msix(irq_fds) {
+                    if let Err(e) = self.device.enable_msix(irq_fds.iter().collect()) {
                         warn!("Could not enable MSI-X: {}", e);
                     }
                 }

virtio-devices/src/device.rs

@@ -32,11 +32,7 @@ pub trait VirtioInterrupt: Send + Sync {
         int_type: &VirtioInterruptType,
         queue: Option<&Queue>,
     ) -> std::result::Result<(), std::io::Error>;
-    fn notifier(
-        &self,
-        _int_type: &VirtioInterruptType,
-        _queue: Option<&Queue>,
-    ) -> Option<&EventFd> {
+    fn notifier(&self, _int_type: &VirtioInterruptType, _queue: Option<&Queue>) -> Option<EventFd> {
         None
     }
 }

virtio-devices/src/transport/pci_device.rs

@@ -755,7 +755,7 @@ impl VirtioInterrupt for VirtioInterruptMsix {
             .trigger(vector as InterruptIndex)
     }
 
-    fn notifier(&self, int_type: &VirtioInterruptType, queue: Option<&Queue>) -> Option<&EventFd> {
+    fn notifier(&self, int_type: &VirtioInterruptType, queue: Option<&Queue>) -> Option<EventFd> {
         let vector = match int_type {
             VirtioInterruptType::Config => self.config_vector.load(Ordering::Acquire),
             VirtioInterruptType::Queue => {

vm-device/src/interrupt/mod.rs

@@ -169,7 +169,7 @@ pub trait InterruptSourceGroup: Send + Sync {
     /// to inject interrupts into a guest, by writing to the file returned
     /// by this method.
     #[allow(unused_variables)]
-    fn notifier(&self, index: InterruptIndex) -> Option<&EventFd> {
+    fn notifier(&self, index: InterruptIndex) -> Option<EventFd> {
         // One use case of the notifier is to implement vhost user backends.
         // For all other implementations we can just return None here.
         None

vmm/src/interrupt.rs

@@ -74,8 +74,12 @@ impl InterruptRoute {
         self.irq_fd.write(1)
     }
 
-    pub fn notifier(&self) -> Option<&EventFd> {
-        Some(&self.irq_fd)
+    pub fn notifier(&self) -> Option<EventFd> {
+        Some(
+            self.irq_fd
+                .try_clone()
+                .expect("Failed cloning interrupt's EventFd"),
+        )
     }
 }
 
@@ -149,7 +153,7 @@ where
         ))
     }
 
-    fn notifier(&self, index: InterruptIndex) -> Option<&EventFd> {
+    fn notifier(&self, index: InterruptIndex) -> Option<EventFd> {
         if let Some(route) = self.irq_routes.get(&index) {
             return route.notifier();
         }