commit 3c3b14d0de9a64590b43aa319b8fe483113b26f9
author Mark Salyzyn <salyzyn@google.com> Wed Oct 31 10:38:15 2018 -0700
committer Mark Salyzyn <salyzyn@google.com> Thu Nov 01 08:14:03 2018 -0700
tree 2c62e1dbad6c9fa1f99e766e9ad8702f6fbb6d11
parent 53e782d5315578f9bf8a11df1df9bae588da3f98

llkd: stutter pre-panic message to both last kernel and last logcat

Test: compile
Bug: 118712403
Change-Id: I9067b9335b2685169bcf8b1dc0248f7ff4315046

llkd/libllkd.cpp

diff --git a/llkd/libllkd.cpp b/llkd/libllkd.cpp
index 7140c3b..0827470 100644
--- a/llkd/libllkd.cpp
+++ b/llkd/libllkd.cpp
@@ -510,8 +510,10 @@
     return android::base::Trim(content) == string;
 }
 
-void llkPanicKernel(bool dump, pid_t tid, const char* state) __noreturn;
-void llkPanicKernel(bool dump, pid_t tid, const char* state) {
+void llkPanicKernel(bool dump, pid_t tid, const char* state,
+                    const std::string& message = "") __noreturn;
+void llkPanicKernel(bool dump, pid_t tid, const char* state, const std::string& message) {
+    if (!message.empty()) LOG(ERROR) << message;
     auto sysrqTriggerFd = llkFileToWriteFd("/proc/sysrq-trigger");
     if (sysrqTriggerFd < 0) {
         // DYB
@@ -537,7 +539,11 @@
         }
         ::usleep(200000);  // let everything settle
     }
-    llkWriteStringToFile("SysRq : Trigger a crash : 'livelock,"s + state + "'\n", "/dev/kmsg");
+    // SysRq message matches kernel format, and propagates through bootstat
+    // ultimately to the boot reason into panic,livelock,<state>.
+    llkWriteStringToFile(message + (message.empty() ? "" : "\n") +
+                                 "SysRq : Trigger a crash : 'livelock,"s + state + "'\n",
+                         "/dev/kmsg");
     android::base::WriteStringToFd("c", sysrqTriggerFd);
     // NOTREACHED
     // DYB
@@ -1098,10 +1104,12 @@
                 }
             }
             // We are here because we have confirmed kernel live-lock
-            LOG(ERROR) << state << ' ' << llkFormat(procp->count) << ' ' << ppid << "->" << pid
-                       << "->" << tid << ' ' << procp->getComm() << " [panic]";
+            const auto message = state + " "s + llkFormat(procp->count) + " " +
+                                 std::to_string(ppid) + "->" + std::to_string(pid) + "->" +
+                                 std::to_string(tid) + " " + procp->getComm() + " [panic]";
             llkPanicKernel(true, tid,
-                           (state == 'Z') ? "zombie" : (state == 'D') ? "driver" : "sleeping");
+                           (state == 'Z') ? "zombie" : (state == 'D') ? "driver" : "sleeping",
+                           message);
         }
         LOG(VERBOSE) << "+closedir()";
     }