From b6dcae31eea135249ca6025b60b1a07faf1356cd Mon Sep 17 00:00:00 2001
From: Jui-Min Lee <fcrh@google.com>
Date: Wed, 6 Jul 2022 15:49:45 +0800
Subject: [PATCH] mem: multi-clients support for SharedMemoryServer

Record the client session with a map instead of a single unique_ptr so
our server can interact with multiple clients at once.

This will also avoid a race condition case where the client thought it
has closed previous connection and is trying to a new one while the
server hasn't clean up the previous entry and raise a fatal error.

Change-Id: Id08154fc4b54d2611629875b3f4e0d66c0e2ed92
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/61049
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Yu-hsin Wang <yuhsingw@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
---
 src/mem/shared_memory_server.cc | 8 +++-----
 src/mem/shared_memory_server.hh | 4 +++-
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/mem/shared_memory_server.cc b/src/mem/shared_memory_server.cc
index 24dd9f6c88..ae5043f749 100644
--- a/src/mem/shared_memory_server.cc
+++ b/src/mem/shared_memory_server.cc
@@ -136,12 +136,10 @@ SharedMemoryServer::ListenSocketEvent::process(int revents)
     int cli_fd = ListenSocket::acceptCloexec(pfd.fd, nullptr, nullptr);
     panic_if(cli_fd < 0, "%s: accept failed: %s", name().c_str(),
              strerror(errno));
-    panic_if(shmServer->clientSocketEvent.get(),
-             "%s: cannot serve two clients at once", name().c_str());
     inform("%s: accept new connection %d", name().c_str(), cli_fd);
-    shmServer->clientSocketEvent.reset(
+    shmServer->clientSocketEvents[cli_fd].reset(
         new ClientSocketEvent(cli_fd, shmServer));
-    pollQueue.schedule(shmServer->clientSocketEvent.get());
+    pollQueue.schedule(shmServer->clientSocketEvents[cli_fd].get());
 }
 
 void
@@ -241,7 +239,7 @@ SharedMemoryServer::ClientSocketEvent::process(int revents)
     // somehow broken. We'll just close the connection and move on.
     inform("%s: closing connection", name().c_str());
     close(pfd.fd);
-    shmServer->clientSocketEvent.reset();
+    shmServer->clientSocketEvents.erase(pfd.fd);
 }
 
 } // namespace memory
diff --git a/src/mem/shared_memory_server.hh b/src/mem/shared_memory_server.hh
index 9102d74571..8f573fef3b 100644
--- a/src/mem/shared_memory_server.hh
+++ b/src/mem/shared_memory_server.hh
@@ -30,6 +30,7 @@
 
 #include <memory>
 #include <string>
+#include <unordered_map>
 
 #include "base/pollevent.hh"
 #include "params/SharedMemoryServer.hh"
@@ -86,7 +87,8 @@ class SharedMemoryServer : public SimObject
 
     int serverFd;
     std::unique_ptr<ListenSocketEvent> listenSocketEvent;
-    std::unique_ptr<ClientSocketEvent> clientSocketEvent;
+    std::unordered_map<int, std::unique_ptr<ClientSocketEvent>>
+        clientSocketEvents;
 };
 
 } // namespace memory