From 03e19871ff75a8493b83a249b0bcd6e19ffca4a4 Mon Sep 17 00:00:00 2001
From: Suren Baghdasaryan <surenb@google.com>
Date: Thu, 4 Jan 2018 10:43:58 -0800
Subject: [PATCH] lmkd: Add ability to trace lmkd kills

For tracing lmkd kills inside kernel it is useful to have traces
indicating when and which process lmkd is killing. By default the
tracing is disabled.

Bug: 63631020
Test: alloc-stress

Change-Id: I3ceb2bde0c292eec55855cb4535927f3b4c5d08b
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 Android.bp |  8 ++++++++
 lmkd.c     | 23 +++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/Android.bp b/Android.bp
index 3f8a503..2731596 100644
--- a/Android.bp
+++ b/Android.bp
@@ -10,4 +10,12 @@ cc_binary {
     cflags: ["-Werror"],
 
     init_rc: ["lmkd.rc"],
+
+    product_variables: {
+        debuggable: {
+            cflags: [
+                "-DLMKD_TRACE_KILLS"
+            ],
+        },
+    },
 }
diff --git a/lmkd.c b/lmkd.c
index fb7cc00..c78461c 100644
--- a/lmkd.c
+++ b/lmkd.c
@@ -37,6 +37,25 @@
 #include <log/log.h>
 #include <processgroup/processgroup.h>
 
+/*
+ * Define LMKD_TRACE_KILLS to record lmkd kills in kernel traces
+ * to profile and correlate with OOM kills
+ */
+#ifdef LMKD_TRACE_KILLS
+
+#define ATRACE_TAG ATRACE_TAG_ALWAYS
+#include <cutils/trace.h>
+
+#define TRACE_KILL_START(pid) ATRACE_INT(__FUNCTION__, pid);
+#define TRACE_KILL_END()      ATRACE_INT(__FUNCTION__, 0);
+
+#else /* LMKD_TRACE_KILLS */
+
+#define TRACE_KILL_START(pid)
+#define TRACE_KILL_END()
+
+#endif /* LMKD_TRACE_KILLS */
+
 #ifndef __unused
 #define __unused __attribute__((__unused__))
 #endif
@@ -638,6 +657,8 @@ static int kill_one_process(struct proc* procp, int min_score_adj,
         return -1;
     }
 
+    TRACE_KILL_START(pid);
+
     r = kill(pid, SIGKILL);
     ALOGI(
         "Killing '%s' (%d), uid %d, adj %d\n"
@@ -646,6 +667,8 @@ static int kill_one_process(struct proc* procp, int min_score_adj,
         level_name[level], min_score_adj);
     pid_remove(pid);
 
+    TRACE_KILL_END();
+
     if (r) {
         ALOGE("kill(%d): errno=%d", procp->pid, errno);
         return -1;