platform-mc / libpldmresponder: Add bypass-terminus-discovery feature and fix event handler NACKs This commit introduces a new platform configuration toggle to optimize PLDM behavior for lightweight topologies (like crash dump listeners) and resolves a critical variable shadowing bug inside the event responder stack. 1. Add `bypass-terminus-discovery` Meson toggle For platforms that only need minimal event routing without massive DBus footprints , this feature flag allows bypassing the traditional heavy discovery phase: - Skips PDR Polling: Short-circuits `getPDRs()` inside the platform manager to suppress heavy I2C cross-traffic for unused sensors and effecters. - Prevents Phantom Chassis Creation: Instantly aborts `createInventoryPath()` in the terminus mapping, preventing bmcweb from blindly exposing the bare terminus (e.g., `MCTP_0`) as a Redfish Chassis object. 2. Fix Completion Code shadowing in `platformEventMessage` A variable shadowing bug (`auto rc = handler(...)`) within the active event handler iteration loop previously resulted in failing handlers falling through. This caused the BMC to illegally return `PLDM_SUCCESS` (0x00) over the wire, even when handlers actively rejected a polled event. The return code variable has been extracted to the outer scope so that any handler failure now immediately breaks the loop and returns the proper NACK. Tested: https://paste.googleplex.com/6678851397222400 With the change we dont see any new entry under Chassis redfish endpoint and crash dump feature is working fine as well. Google-Bug-Id: 556580550 Change-Id: I1fcd2cce9fa268054028f3a868abb70863fba7d4 Signed-off-by: Vikram Gara <vikramgara@google.com>

diff --git a/libpldmresponder/platform.cpp b/libpldmresponder/platform.cpp
index b414704..c2f450f 100644
--- a/libpldmresponder/platform.cpp
+++ b/libpldmresponder/platform.cpp

@@ -855,19 +855,21 @@
         try
         {
             const auto& handlers = eventHandlers.at(eventClass);
+            int handlerRc = PLDM_SUCCESS;
             bool oneFailedHandler = false;
             for (const auto& handler : handlers)
             {
-                auto rc =
+                handlerRc =
                     handler(request, payloadLength, formatVersion, tid, offset);
-                if (rc != PLDM_SUCCESS)
+                if (handlerRc != PLDM_SUCCESS)
                 {
                     oneFailedHandler = true;
+                    break;
                 }
             }
             if (oneFailedHandler)
             {
-                return CmdHandler::ccOnlyResponse(request, rc);
+                return CmdHandler::ccOnlyResponse(request, handlerRc);
             }
         }
         catch (const std::out_of_range& e)

diff --git a/meson.build b/meson.build
index 53f24dd..e02ccb9 100644
--- a/meson.build
+++ b/meson.build

@@ -52,6 +52,9 @@
 if get_option('sensor-polling').allowed()
     conf_data.set('SENSOR_POLLING', 1)
 endif
+if get_option('bypass-terminus-discovery').allowed()
+    conf_data.set('BYPASS_TERMINUS_DISCOVERY', 1)
+endif
 
 if get_option('libpldmresponder').allowed()
     conf_data.set_quoted('BIOS_JSONS_DIR', join_paths(package_datadir, 'bios'))

diff --git a/meson.options b/meson.options
index d7c8772..74cdb00 100644
--- a/meson.options
+++ b/meson.options

@@ -259,3 +259,10 @@
     value: 'enabled',
     description: 'Enable numeric sensor polling in platform-mc',
 )
+
+option(
+    'bypass-terminus-discovery',
+    type: 'feature',
+    value: 'disabled',
+    description: 'Bypass PDR fetching and chassis DBus creation for terminii',
+)

diff --git a/platform-mc/platform_manager.cpp b/platform-mc/platform_manager.cpp
index 548cb1a..a980741 100644
--- a/platform-mc/platform_manager.cpp
+++ b/platform-mc/platform_manager.cpp

@@ -56,6 +56,7 @@
             }
         }
 
+#ifndef BYPASS_TERMINUS_DISCOVERY
         if (terminus->doesSupportCommand(PLDM_PLATFORM, PLDM_GET_PDR))
         {
             auto rc = co_await getPDRs(terminus);
@@ -69,6 +70,7 @@
 
             terminus->parseTerminusPDRs();
         }
+#endif
 
         /**
          * Need terminus name from PDRs before updating Inventory object with

diff --git a/platform-mc/sensor_manager.cpp b/platform-mc/sensor_manager.cpp
index 7a44a5a..31a8581 100644
--- a/platform-mc/sensor_manager.cpp
+++ b/platform-mc/sensor_manager.cpp

@@ -155,7 +155,7 @@
                 rcOpt = PLDM_SUCCESS;
             }
         }),
-        exec::default_task_context<void>(exec::inline_scheduler{}));
+        exec::default_task_context<void>(stdexec::inline_scheduler{}));
 }
 
 exec::task<int> SensorManager::doSensorPollingTask(pldm_tid_t tid)

diff --git a/platform-mc/terminus.cpp b/platform-mc/terminus.cpp
index fdaacf4..2a25092 100644
--- a/platform-mc/terminus.cpp
+++ b/platform-mc/terminus.cpp

@@ -89,6 +89,13 @@
 
 bool Terminus::createInventoryPath(std::string tName)
 {
+#ifdef BYPASS_TERMINUS_DISCOVERY
+    // HACK: Immediately return false to prevent pldmd from exposing the
+    // terminus under /xyz/openbmc_project/inventory/system/board/ which bubbles
+    // up as a Redfish Chassis object (e.g., MCTP_0).
+    return false;
+#endif
+
     if (tName.empty())
     {
         return false;

diff --git a/platform-mc/terminus_manager.cpp b/platform-mc/terminus_manager.cpp
index 5270da8..a111a54 100644
--- a/platform-mc/terminus_manager.cpp
+++ b/platform-mc/terminus_manager.cpp

@@ -170,7 +170,7 @@
     auto& [scope, rcOpt] = discoverMctpTerminusTaskHandle.emplace();
     scope.spawn(discoverMctpTerminusTask() |
                     stdexec::then([&](int rc) { rcOpt.emplace(rc); }),
-                exec::default_task_context<void>(exec::inline_scheduler{}));
+                exec::default_task_context<void>(stdexec::inline_scheduler{}));
 }
 
 TerminiMapper::iterator TerminusManager::findTerminusPtr(

diff --git a/requester/test/handler_test.cpp b/requester/test/handler_test.cpp
index caa4663..a3c06e5 100644
--- a/requester/test/handler_test.cpp
+++ b/requester/test/handler_test.cpp

@@ -197,7 +197,7 @@
 
             EXPECT_EQ(validResponse, true);
         }),
-        exec::default_task_context<void>(exec::inline_scheduler{}));
+        exec::default_task_context<void>(stdexec::inline_scheduler{}));
 
     pldm::Response mockResponse(sizeof(pldm_msg_hdr) + sizeof(uint8_t), 0);
     auto mockResponsePtr =
@@ -231,7 +231,7 @@
 
             EXPECT_TRUE(false); // unreachable
         }) | stdexec::upon_stopped([&] { stopped = true; }),
-        exec::default_task_context<void>(exec::inline_scheduler{}));
+        exec::default_task_context<void>(stdexec::inline_scheduler{}));
 
     scope.request_stop();
 
@@ -285,7 +285,7 @@
 
                     EXPECT_EQ(expectedTid, respTid);
                 }),
-                exec::default_task_context<void>(exec::inline_scheduler{}));
+                exec::default_task_context<void>(stdexec::inline_scheduler{}));
 
     pldm::Response mockResponse(sizeof(pldm_msg_hdr) + PLDM_GET_TID_RESP_BYTES,
                                 0);