build: Remove unnecessary Result<> returns

If the function can never return an error this is now a clippy failure:

error: this function's return value is unnecessarily wrapped by `Result`
   --> virtio-devices/src/watchdog.rs:215:5
    |
215 | /     fn set_state(&mut self, state: &WatchdogState) -> io::Result<()> {
216 | |         self.common.avail_features = state.avail_features;
217 | |         self.common.acked_features = state.acked_features;
218 | |         // When restoring enable the watchdog if it was previously enabled. We reset the timer
...   |
223 | |         Ok(())
224 | |     }
    | |_____^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_wraps

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

vmm/src/config.rs

@@ -1726,7 +1726,7 @@ mod tests {
     use super::*;
 
     #[test]
-    fn test_option_parser() -> std::result::Result<(), OptionParserError> {
+    fn test_option_parser() {
         let mut parser = OptionParser::new();
         parser
             .add("size")
@@ -1742,7 +1742,6 @@ mod tests {
         assert_eq!(parser.get("size"), Some("128M".to_owned()));
         assert!(!parser.is_set("mergeable"));
         assert!(parser.is_set("size"));
-        Ok(())
     }
 
     #[test]
@@ -2271,7 +2270,7 @@ mod tests {
     }
 
     #[test]
-    fn test_config_validation() -> Result<()> {
+    fn test_config_validation() {
         let valid_config = VmConfig {
             cpus: CpusConfig {
                 boot_vcpus: 1,
@@ -2432,7 +2431,5 @@ mod tests {
         invalid_config.memory.hugepages = true;
         invalid_config.memory.hugepage_size = Some(3 << 20);
         assert!(invalid_config.validate().is_err());
-
-        Ok(())
     }
 }

vmm/src/cpu.rs

@@ -992,12 +992,11 @@ impl CpuManager {
         Ok(())
     }
 
-    fn mark_vcpus_for_removal(&mut self, desired_vcpus: u8) -> Result<()> {
+    fn mark_vcpus_for_removal(&mut self, desired_vcpus: u8) {
         // Mark vCPUs for removal, actual removal happens on ejection
         for cpu_id in desired_vcpus..self.present_vcpus() {
             self.vcpu_states[usize::from(cpu_id)].removing = true;
         }
-        Ok(())
     }
 
     fn remove_vcpu(&mut self, cpu_id: u8) -> Result<()> {
@@ -1049,7 +1048,10 @@ impl CpuManager {
                 self.activate_vcpus(desired_vcpus, true)?;
                 Ok(true)
             }
-            cmp::Ordering::Less => self.mark_vcpus_for_removal(desired_vcpus).and(Ok(true)),
+            cmp::Ordering::Less => {
+                self.mark_vcpus_for_removal(desired_vcpus);
+                Ok(true)
+            }
             _ => Ok(false),
         }
     }

vmm/src/device_manager.rs

@@ -1097,11 +1097,9 @@ impl DeviceManager {
         }
     }
 
-    fn set_state(&mut self, state: &DeviceManagerState) -> DeviceManagerResult<()> {
+    fn set_state(&mut self, state: &DeviceManagerState) {
         self.device_tree = Arc::new(Mutex::new(state.device_tree.clone()));
         self.device_id_cnt = state.device_id_cnt;
-
-        Ok(())
     }
 
     #[cfg(target_arch = "aarch64")]
@@ -3726,9 +3724,7 @@ impl Snapshottable for DeviceManager {
                     MigratableError::Restore(anyhow!("Could not deserialize DeviceManager {}", e))
                 })?;
 
-            self.set_state(&device_manager_state).map_err(|e| {
-                MigratableError::Restore(anyhow!("Could not restore DeviceManager state {:?}", e))
-            })?;
+            self.set_state(&device_manager_state);
         } else {
             return Err(MigratableError::Restore(anyhow!(
                 "Could not find DeviceManager snapshot section"

vmm/src/lib.rs

@@ -539,10 +539,10 @@ impl Vmm {
         }
     }
 
-    fn vmm_ping(&self) -> result::Result<VmmPingResponse, ApiError> {
-        Ok(VmmPingResponse {
+    fn vmm_ping(&self) -> VmmPingResponse {
+        VmmPingResponse {
             version: self.version.clone(),
-        })
+        }
     }
 
     fn vm_delete(&mut self) -> result::Result<(), VmError> {
@@ -1205,9 +1205,9 @@ impl Vmm {
                                     sender.send(response).map_err(Error::ApiResponseSend)?;
                                 }
                                 ApiRequest::VmmPing(sender) => {
-                                    let response = self.vmm_ping().map(ApiResponsePayload::VmmPing);
+                                    let response = ApiResponsePayload::VmmPing(self.vmm_ping());
 
-                                    sender.send(response).map_err(Error::ApiResponseSend)?;
+                                    sender.send(Ok(response)).map_err(Error::ApiResponseSend)?;
                                 }
                                 ApiRequest::VmPause(sender) => {
                                     let response = self