commit e170d1ac8d62670f03eee7d7b7ef9a055754bacc
author Tom Cherry <tomcherry@google.com> Fri May 01 16:45:25 2020 -0700
committer Tom Cherry <tomcherry@google.com> Mon May 04 10:02:51 2020 -0700
tree ae0a68d722148890c20fd7d2c519fb93d74424f3
parent 1a12ae3a256d4d8a0ad08d1ed5e37d7178705287

logd: don't use SIGHUP to reinitialize

It doesn't look like there are any users, since there is a much better
mechanism, `logd --reinit` that exists for this behavior.  The
settings app and init.rc use that mechanism and they are the two major
clients that force logd to reinitialize.

This saves us from creating a thread and marginally cleans up
main.cpp.

Test: log reinitialization works
Change-Id: Icdb56b6f59adbba82812231a4f3a6ffd1a7955fc

logd/main.cpp

diff --git a/logd/main.cpp b/logd/main.cpp
index 8713147..c4750ec 100644
--- a/logd/main.cpp
+++ b/logd/main.cpp
@@ -151,50 +151,6 @@
     }
 }
 
-static sem_t reinit;
-static bool reinit_running = false;
-static LogBuffer* logBuf = nullptr;
-
-static void* reinit_thread_start(void* /*obj*/) {
-    prctl(PR_SET_NAME, "logd.daemon");
-
-    while (reinit_running && !sem_wait(&reinit) && reinit_running) {
-        if (fdDmesg >= 0) {
-            static const char reinit_message[] = { KMSG_PRIORITY(LOG_INFO),
-                                                   'l',
-                                                   'o',
-                                                   'g',
-                                                   'd',
-                                                   '.',
-                                                   'd',
-                                                   'a',
-                                                   'e',
-                                                   'm',
-                                                   'o',
-                                                   'n',
-                                                   ':',
-                                                   ' ',
-                                                   'r',
-                                                   'e',
-                                                   'i',
-                                                   'n',
-                                                   'i',
-                                                   't',
-                                                   '\n' };
-            write(fdDmesg, reinit_message, sizeof(reinit_message));
-        }
-
-        // Anything that reads persist.<property>
-        if (logBuf) {
-            logBuf->init();
-            logBuf->initPrune(nullptr);
-        }
-        android::ReReadEventLogTags();
-    }
-
-    return nullptr;
-}
-
 char* android::uidToName(uid_t u) {
     struct Userdata {
         uid_t uid;
@@ -221,12 +177,6 @@
     return userdata.name;
 }
 
-// Serves as a global method to trigger reinitialization
-// and as a function that can be provided to signal().
-void reinit_signal_handler(int /*signal*/) {
-    sem_post(&reinit);
-}
-
 static void readDmesg(LogAudit* al, LogKlog* kl) {
     if (!al && !kl) {
         return;
@@ -337,25 +287,6 @@
         return EXIT_FAILURE;
     }
 
-    // Reinit Thread
-    sem_init(&reinit, 0, 0);
-    pthread_attr_t attr;
-    if (!pthread_attr_init(&attr)) {
-        struct sched_param param;
-
-        memset(&param, 0, sizeof(param));
-        pthread_attr_setschedparam(&attr, &param);
-        pthread_attr_setschedpolicy(&attr, SCHED_BATCH);
-        if (!pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED)) {
-            pthread_t thread;
-            reinit_running = true;
-            if (pthread_create(&thread, &attr, reinit_thread_start, nullptr)) {
-                reinit_running = false;
-            }
-        }
-        pthread_attr_destroy(&attr);
-    }
-
     // A cache of event log tags
     LogTags log_tags;
 
@@ -368,9 +299,7 @@
     // LogBuffer is the object which is responsible for holding all
     // log entries.
 
-    logBuf = new LogBuffer(times, &log_tags);
-
-    signal(SIGHUP, reinit_signal_handler);
+    LogBuffer* logBuf = new LogBuffer(times, &log_tags);
 
     if (__android_logger_property_get_bool(
             "logd.statistics", BOOL_DEFAULT_TRUE | BOOL_DEFAULT_FLAG_PERSIST |