agent: Handle uevent remove actions

uevents with action=remove was ignored causing the agent to reuse stale
data in the device map. This patch adds handling of such uevents.

Fixes #2405

Signed-off-by: Haitao Li <lihaitao@gmail.com>

src/agent/src/linux_abi.rs

@@ -95,6 +95,7 @@ pub const SYSTEM_DEV_PATH: &str = "/dev";
 // Linux UEvent related consts.
 pub const U_EVENT_ACTION: &str = "ACTION";
 pub const U_EVENT_ACTION_ADD: &str = "add";
+pub const U_EVENT_ACTION_REMOVE: &str = "remove";
 pub const U_EVENT_DEV_PATH: &str = "DEVPATH";
 pub const U_EVENT_SUB_SYSTEM: &str = "SUBSYSTEM";
 pub const U_EVENT_SEQ_NUM: &str = "SEQNUM";

src/agent/src/uevent.rs

@@ -97,10 +97,18 @@ impl Uevent {
         })
     }
 
+    #[instrument]
+    async fn process_remove(&self, logger: &Logger, sandbox: &Arc<Mutex<Sandbox>>) {
+        let mut sb = sandbox.lock().await;
+        sb.uevent_map.remove(&self.devpath);
+    }
+
     #[instrument]
     async fn process(&self, logger: &Logger, sandbox: &Arc<Mutex<Sandbox>>) {
         if self.action == U_EVENT_ACTION_ADD {
             return self.process_add(logger, sandbox).await;
+        } else if self.action == U_EVENT_ACTION_REMOVE {
+            return self.process_remove(logger, sandbox).await;
         }
         debug!(*logger, "ignoring event"; "uevent" => format!("{:?}", self));
     }