commit c976e73bbdfd512482d0ea0c5e10afd53ba85e1e
author Dimitry Ivanov <dimitry@google.com> Thu Jan 19 12:48:27 2017 -0800
committer Dimitry Ivanov <dimitry@google.com> Thu Jan 19 14:44:03 2017 -0800
tree abe5c8f3901d739830b18639fedb63710c4503ad
parent 04c55e6ed7259c5fb0c3d951f4995778feff2a34

Fix deadlock between vold and init

By setting property after listeners are initialized
we avoid deadlock between vold and init where
vold is waiting on property_service while init is blocked
(and therefore is not able to accept connections) on vdc
which is attempting to communicate with vold.

(This also speeds up boot by 250ms)

Test: Boot a device, check locks and make sure there is no timeout
      on property_set(.)
Test: Successfully boot a device with new property service protocol.
Bug: http://b/34278978
Change-Id: I9547d2f19cb35aa452bf01fbff0eb4b32a4824a4

main.cpp

diff --git a/main.cpp b/main.cpp
index 9cbcf88..68477ac 100644
--- a/main.cpp
+++ b/main.cpp
@@ -39,7 +39,7 @@
 #include <dirent.h>
 #include <fs_mgr.h>
 
-static int process_config(VolumeManager *vm);
+static int process_config(VolumeManager *vm, bool* has_adoptable);
 static void coldboot(const char *path);
 static void parse_args(int argc, char** argv);
 
@@ -106,7 +106,9 @@
         exit(1);
     }
 
-    if (process_config(vm)) {
+    bool has_adoptable;
+
+    if (process_config(vm, &has_adoptable)) {
         PLOG(ERROR) << "Error reading configuration... continuing anyways";
     }
 
@@ -131,6 +133,10 @@
         exit(1);
     }
 
+    // This call should go after listeners are started to avoid
+    // a deadlock between vold and init (see b/34278978 for details)
+    property_set("vold.has_adoptable", has_adoptable ? "1" : "0");
+
     // Eventually we'll become the monitoring thread
     while(1) {
         sleep(1000);
@@ -207,7 +213,7 @@
     }
 }
 
-static int process_config(VolumeManager *vm) {
+static int process_config(VolumeManager *vm, bool* has_adoptable) {
     std::string path(android::vold::DefaultFstabPath());
     fstab = fs_mgr_read_fstab(path.c_str());
     if (!fstab) {
@@ -216,7 +222,7 @@
     }
 
     /* Loop through entries looking for ones that vold manages */
-    bool has_adoptable = false;
+    *has_adoptable = false;
     for (int i = 0; i < fstab->num_entries; i++) {
         if (fs_mgr_is_voldmanaged(&fstab->recs[i])) {
             if (fs_mgr_is_nonremovable(&fstab->recs[i])) {
@@ -230,7 +236,7 @@
 
             if (fs_mgr_is_encryptable(&fstab->recs[i])) {
                 flags |= android::vold::Disk::Flags::kAdoptable;
-                has_adoptable = true;
+                *has_adoptable = true;
             }
             if (fs_mgr_is_noemulatedsd(&fstab->recs[i])
                     || property_get_bool("vold.debug.default_primary", false)) {
@@ -241,6 +247,5 @@
                     new VolumeManager::DiskSource(sysPattern, nickname, flags)));
         }
     }
-    property_set("vold.has_adoptable", has_adoptable ? "1" : "0");
     return 0;
 }