diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index 31ef3b5..ad48dd1 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -681,7 +681,7 @@
     }
 }
 
-bool ReadFstabFromFile(const std::string& path, Fstab* fstab) {
+bool ReadFstabFromFile(const std::string& path, Fstab* fstab_out) {
     auto fstab_file = std::unique_ptr<FILE, decltype(&fclose)>{fopen(path.c_str(), "re"), fclose};
     if (!fstab_file) {
         PERROR << __FUNCTION__ << "(): cannot open file: '" << path << "'";
@@ -690,31 +690,43 @@
 
     bool is_proc_mounts = path == "/proc/mounts";
 
-    if (!ReadFstabFile(fstab_file.get(), is_proc_mounts, fstab)) {
+    Fstab fstab;
+    if (!ReadFstabFile(fstab_file.get(), is_proc_mounts, &fstab)) {
         LERROR << __FUNCTION__ << "(): failed to load fstab from : '" << path << "'";
         return false;
     }
-    if (!is_proc_mounts && !access(android::gsi::kGsiBootedIndicatorFile, F_OK)) {
-        // This is expected to fail if host is android Q, since Q doesn't
-        // support DSU slotting. The DSU "active" indicator file would be
-        // non-existent or empty if DSU is enabled within the guest system.
-        // In that case, just use the default slot name "dsu".
-        std::string dsu_slot;
-        if (!android::gsi::GetActiveDsu(&dsu_slot)) {
-            PWARNING << __FUNCTION__ << "(): failed to get active dsu slot";
+    if (!is_proc_mounts) {
+        if (!access(android::gsi::kGsiBootedIndicatorFile, F_OK)) {
+            // This is expected to fail if host is android Q, since Q doesn't
+            // support DSU slotting. The DSU "active" indicator file would be
+            // non-existent or empty if DSU is enabled within the guest system.
+            // In that case, just use the default slot name "dsu".
+            std::string dsu_slot;
+            if (!android::gsi::GetActiveDsu(&dsu_slot) && errno != ENOENT) {
+                PERROR << __FUNCTION__ << "(): failed to get active DSU slot";
+                return false;
+            }
+            if (dsu_slot.empty()) {
+                dsu_slot = "dsu";
+                LWARNING << __FUNCTION__ << "(): assuming default DSU slot: " << dsu_slot;
+            }
+            // This file is non-existent on Q vendor.
+            std::string lp_names;
+            if (!ReadFileToString(gsi::kGsiLpNamesFile, &lp_names) && errno != ENOENT) {
+                PERROR << __FUNCTION__ << "(): failed to read DSU LP names";
+                return false;
+            }
+            TransformFstabForDsu(&fstab, dsu_slot, Split(lp_names, ","));
+        } else if (errno != ENOENT) {
+            PERROR << __FUNCTION__ << "(): failed to access() DSU booted indicator";
+            return false;
         }
-        if (dsu_slot.empty()) {
-            dsu_slot = "dsu";
-        }
-
-        std::string lp_names;
-        ReadFileToString(gsi::kGsiLpNamesFile, &lp_names);
-        TransformFstabForDsu(fstab, dsu_slot, Split(lp_names, ","));
     }
 
-    SkipMountingPartitions(fstab, false /* verbose */);
-    EnableMandatoryFlags(fstab);
+    SkipMountingPartitions(&fstab, false /* verbose */);
+    EnableMandatoryFlags(&fstab);
 
+    *fstab_out = std::move(fstab);
     return true;
 }
 
@@ -799,10 +811,8 @@
 
 // Loads the fstab file and combines with fstab entries passed in from device tree.
 bool ReadDefaultFstab(Fstab* fstab) {
-    Fstab dt_fstab;
-    ReadFstabFromDt(&dt_fstab, false /* verbose */);
-
-    *fstab = std::move(dt_fstab);
+    fstab->clear();
+    ReadFstabFromDt(fstab, false /* verbose */);
 
     std::string default_fstab_path;
     // Use different fstab paths for normal boot and recovery boot, respectively
@@ -813,16 +823,14 @@
     }
 
     Fstab default_fstab;
-    if (!default_fstab_path.empty()) {
-        ReadFstabFromFile(default_fstab_path, &default_fstab);
+    if (!default_fstab_path.empty() && ReadFstabFromFile(default_fstab_path, &default_fstab)) {
+        for (auto&& entry : default_fstab) {
+            fstab->emplace_back(std::move(entry));
+        }
     } else {
         LINFO << __FUNCTION__ << "(): failed to find device default fstab";
     }
 
-    for (auto&& entry : default_fstab) {
-        fstab->emplace_back(std::move(entry));
-    }
-
     return !fstab->empty();
 }
 
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapuserd_client.h b/fs_mgr/libsnapshot/include/libsnapshot/snapuserd_client.h
index 1dab361..280e857 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/snapuserd_client.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapuserd_client.h
@@ -69,6 +69,8 @@
     // must ONLY be called if the control device has already been deleted.
     bool WaitForDeviceDelete(const std::string& control_device);
 
+    void CloseConnection() { sockfd_ = {}; }
+
     // Detach snapuserd. This shuts down the listener socket, and will cause
     // snapuserd to gracefully exit once all handler threads have terminated.
     // This should only be used on first-stage instances of snapuserd.
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index 2c5bf75..a0a1e4f 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -2297,6 +2297,17 @@
             return false;
         }
     }
+
+    // Terminate the daemon and release the snapuserd_client_ object.
+    // If we need to re-connect with the daemon, EnsureSnapuserdConnected()
+    // will re-create the object and establish the socket connection.
+    if (snapuserd_client_) {
+        LOG(INFO) << "Shutdown snapuserd daemon";
+        snapuserd_client_->DetachSnapuserd();
+        snapuserd_client_->CloseConnection();
+        snapuserd_client_ = nullptr;
+    }
+
     return true;
 }
 
diff --git a/fs_mgr/libsnapshot/snapshot_test.cpp b/fs_mgr/libsnapshot/snapshot_test.cpp
index 6ed0129..8fae00b 100644
--- a/fs_mgr/libsnapshot/snapshot_test.cpp
+++ b/fs_mgr/libsnapshot/snapshot_test.cpp
@@ -2019,6 +2019,8 @@
 
     // Read bytes back and verify they match the cache.
     ASSERT_TRUE(IsPartitionUnchanged("sys_b"));
+
+    ASSERT_TRUE(sm->UnmapAllSnapshots());
 }
 
 TEST_F(SnapshotUpdateTest, CancelOnTargetSlot) {
diff --git a/init/ueventd_parser.cpp b/init/ueventd_parser.cpp
index cab988b..2221228 100644
--- a/init/ueventd_parser.cpp
+++ b/init/ueventd_parser.cpp
@@ -106,10 +106,10 @@
     }
 
     if (std::find_if(external_firmware_handlers->begin(), external_firmware_handlers->end(),
-                     [&args](const auto& other) { return other.devpath == args[2]; }) !=
+                     [&args](const auto& other) { return other.devpath == args[1]; }) !=
         external_firmware_handlers->end()) {
         return Error() << "found a previous external_firmware_handler with the same devpath, '"
-                       << args[2] << "'";
+                       << args[1] << "'";
     }
 
     passwd* pwd = getpwnam(args[2].c_str());
diff --git a/init/ueventd_parser_test.cpp b/init/ueventd_parser_test.cpp
index b604c53..4e63ba5 100644
--- a/init/ueventd_parser_test.cpp
+++ b/init/ueventd_parser_test.cpp
@@ -45,6 +45,13 @@
     EXPECT_EQ(expected.attribute_, test.attribute_);
 }
 
+void TestExternalFirmwareHandler(const ExternalFirmwareHandler& expected,
+                                 const ExternalFirmwareHandler& test) {
+    EXPECT_EQ(expected.devpath, test.devpath) << expected.devpath;
+    EXPECT_EQ(expected.uid, test.uid) << expected.uid;
+    EXPECT_EQ(expected.handler_path, test.handler_path) << expected.handler_path;
+}
+
 template <typename T, typename F>
 void TestVector(const T& expected, const T& test, F function) {
     ASSERT_EQ(expected.size(), test.size());
@@ -67,6 +74,8 @@
     TestVector(expected.sysfs_permissions, result.sysfs_permissions, TestSysfsPermissions);
     TestVector(expected.dev_permissions, result.dev_permissions, TestPermissions);
     EXPECT_EQ(expected.firmware_directories, result.firmware_directories);
+    TestVector(expected.external_firmware_handlers, result.external_firmware_handlers,
+               TestExternalFirmwareHandler);
 }
 
 TEST(ueventd_parser, EmptyFile) {
@@ -144,7 +153,7 @@
     auto ueventd_file = R"(
 external_firmware_handler devpath root handler_path
 external_firmware_handler /devices/path/firmware/something001.bin system /vendor/bin/firmware_handler.sh
-external_firmware_handler /devices/path/firmware/something001.bin radio "/vendor/bin/firmware_handler.sh --has --arguments"
+external_firmware_handler /devices/path/firmware/something002.bin radio "/vendor/bin/firmware_handler.sh --has --arguments"
 )";
 
     auto external_firmware_handlers = std::vector<ExternalFirmwareHandler>{
@@ -159,7 +168,7 @@
                     "/vendor/bin/firmware_handler.sh",
             },
             {
-                    "/devices/path/firmware/something001.bin",
+                    "/devices/path/firmware/something002.bin",
                     AID_RADIO,
                     "/vendor/bin/firmware_handler.sh --has --arguments",
             },
diff --git a/libstats/pull_rust/Android.bp b/libstats/pull_rust/Android.bp
new file mode 100644
index 0000000..354c7b3
--- /dev/null
+++ b/libstats/pull_rust/Android.bp
@@ -0,0 +1,59 @@
+//
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+rust_bindgen {
+    name: "libstatspull_bindgen",
+    wrapper_src: "statslog.h",
+    crate_name: "statspull_bindgen",
+    source_stem: "bindings",
+    bindgen_flags: [
+        "--size_t-is-usize",
+        "--whitelist-function=AStatsEventList_addStatsEvent",
+        "--whitelist-function=AStatsEvent_.*",
+        "--whitelist-function=AStatsManager_.*",
+        "--whitelist-var=AStatsManager_.*",
+    ],
+    target: {
+        android: {
+            shared_libs: [
+                "libstatspull",
+                "libstatssocket",
+            ],
+        },
+        host: {
+            static_libs: [
+                "libstatspull",
+                "libstatssocket",
+            ],
+        },
+    },
+}
+
+rust_library {
+    name: "libstatspull_rust",
+    crate_name: "statspull_rust",
+    srcs: ["stats_pull.rs"],
+    rustlibs: [
+        "liblazy_static",
+        "liblog_rust",
+        "libstatslog_rust_header",
+        "libstatspull_bindgen",
+    ],
+}
diff --git a/libstats/pull_rust/stats_pull.rs b/libstats/pull_rust/stats_pull.rs
new file mode 100644
index 0000000..174125e
--- /dev/null
+++ b/libstats/pull_rust/stats_pull.rs
@@ -0,0 +1,170 @@
+// Copyright 2021, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! A Rust interface for the StatsD pull API.
+
+use lazy_static::lazy_static;
+use statslog_rust_header::{Atoms, Stat, StatsError};
+use statspull_bindgen::*;
+use std::collections::HashMap;
+use std::convert::TryInto;
+use std::os::raw::c_void;
+use std::sync::Mutex;
+
+/// The return value of callbacks.
+pub type StatsPullResult = Vec<Box<dyn Stat>>;
+
+/// A wrapper for AStatsManager_PullAtomMetadata.
+/// It calls AStatsManager_PullAtomMetadata_release on drop.
+pub struct Metadata {
+    metadata: *mut AStatsManager_PullAtomMetadata,
+}
+
+impl Metadata {
+    /// Calls AStatsManager_PullAtomMetadata_obtain.
+    pub fn new() -> Self {
+        // Safety: We panic if the memory allocation fails.
+        let metadata = unsafe { AStatsManager_PullAtomMetadata_obtain() };
+        if metadata.is_null() {
+            panic!("Cannot obtain pull atom metadata.");
+        } else {
+            Metadata { metadata }
+        }
+    }
+
+    /// Calls AStatsManager_PullAtomMetadata_setCoolDownMillis.
+    pub fn set_cooldown_millis(&mut self, cooldown_millis: i64) {
+        // Safety: Metadata::new ensures that self.metadata is a valid object.
+        unsafe { AStatsManager_PullAtomMetadata_setCoolDownMillis(self.metadata, cooldown_millis) }
+    }
+
+    /// Calls AStatsManager_PullAtomMetadata_getCoolDownMillis.
+    pub fn get_cooldown_millis(&self) -> i64 {
+        // Safety: Metadata::new ensures that self.metadata is a valid object.
+        unsafe { AStatsManager_PullAtomMetadata_getCoolDownMillis(self.metadata) }
+    }
+
+    /// Calls AStatsManager_PullAtomMetadata_setTimeoutMillis.
+    pub fn set_timeout_millis(&mut self, timeout_millis: i64) {
+        // Safety: Metadata::new ensures that self.metadata is a valid object.
+        unsafe { AStatsManager_PullAtomMetadata_setTimeoutMillis(self.metadata, timeout_millis) }
+    }
+
+    /// Calls AStatsManager_PullAtomMetadata_getTimeoutMillis.
+    pub fn get_timeout_millis(&self) -> i64 {
+        // Safety: Metadata::new ensures that self.metadata is a valid object.
+        unsafe { AStatsManager_PullAtomMetadata_getTimeoutMillis(self.metadata) }
+    }
+
+    /// Calls AStatsManager_PullAtomMetadata_setAdditiveFields.
+    pub fn set_additive_fields(&mut self, additive_fields: &mut Vec<i32>) {
+        // Safety: Metadata::new ensures that self.metadata is a valid object.
+        unsafe {
+            AStatsManager_PullAtomMetadata_setAdditiveFields(
+                self.metadata,
+                additive_fields.as_mut_ptr(),
+                additive_fields.len().try_into().expect("Cannot convert length to i32"),
+            )
+        }
+    }
+
+    /// Calls AStatsManager_PullAtomMetadata_getAdditiveFields.
+    pub fn get_additive_fields(&self) -> Vec<i32> {
+        // Safety: Metadata::new ensures that self.metadata is a valid object.
+        // We call getNumAdditiveFields to ensure we pass getAdditiveFields a large enough array.
+        unsafe {
+            let num_fields = AStatsManager_PullAtomMetadata_getNumAdditiveFields(self.metadata)
+                .try_into()
+                .expect("Cannot convert num additive fields to usize");
+            let mut fields = vec![0; num_fields];
+            AStatsManager_PullAtomMetadata_getAdditiveFields(self.metadata, fields.as_mut_ptr());
+            fields
+        }
+    }
+}
+
+impl Drop for Metadata {
+    fn drop(&mut self) {
+        // Safety: Metadata::new ensures that self.metadata is a valid object.
+        unsafe { AStatsManager_PullAtomMetadata_release(self.metadata) }
+    }
+}
+
+impl Default for Metadata {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+lazy_static! {
+    static ref COOKIES: Mutex<HashMap<i32, fn() -> StatsPullResult>> = Mutex::new(HashMap::new());
+}
+
+// Safety: We store our callbacks in the global so they are valid.
+unsafe extern "C" fn callback_wrapper(
+    atom_tag: i32,
+    data: *mut AStatsEventList,
+    _cookie: *mut c_void,
+) -> AStatsManager_PullAtomCallbackReturn {
+    if !data.is_null() {
+        let map = COOKIES.lock().unwrap();
+        let cb = map.get(&atom_tag);
+        match cb {
+            None => log::error!("No callback found for {}", atom_tag),
+            Some(cb) => {
+                let stats = cb();
+                let result = stats
+                    .iter()
+                    .map(|stat| stat.add_astats_event(&mut *data))
+                    .collect::<Result<Vec<()>, StatsError>>();
+                match result {
+                    Ok(_) => {
+                        return AStatsManager_PULL_SUCCESS as AStatsManager_PullAtomCallbackReturn
+                    }
+                    _ => log::error!("Error adding astats events: {:?}", result),
+                }
+            }
+        }
+    }
+    AStatsManager_PULL_SKIP as AStatsManager_PullAtomCallbackReturn
+}
+
+/// Rust wrapper for AStatsManager_setPullAtomCallback.
+pub fn set_pull_atom_callback(
+    atom: Atoms,
+    metadata: Option<&Metadata>,
+    callback: fn() -> StatsPullResult,
+) {
+    COOKIES.lock().unwrap().insert(atom as i32, callback);
+    let metadata_raw = match metadata {
+        Some(m) => m.metadata,
+        None => std::ptr::null_mut(),
+    };
+    // Safety: We pass a valid function as the callback.
+    unsafe {
+        AStatsManager_setPullAtomCallback(
+            atom as i32,
+            metadata_raw,
+            Some(callback_wrapper),
+            std::ptr::null_mut(),
+        );
+    }
+}
+
+/// Rust wrapper for AStatsManager_clearPullAtomCallback.
+pub fn clear_pull_atom_callback(atom: Atoms) {
+    COOKIES.lock().unwrap().remove(&(atom as i32));
+    // Safety: No memory allocations.
+    unsafe { AStatsManager_clearPullAtomCallback(atom as i32) }
+}
diff --git a/libstats/pull_rust/statslog.h b/libstats/pull_rust/statslog.h
new file mode 100644
index 0000000..983fb7b
--- /dev/null
+++ b/libstats/pull_rust/statslog.h
@@ -0,0 +1,3 @@
+#pragma once
+
+#include "stats_pull_atom_callback.h"
diff --git a/libutils/RefBase.cpp b/libutils/RefBase.cpp
index 8e45226..b57e287 100644
--- a/libutils/RefBase.cpp
+++ b/libutils/RefBase.cpp
@@ -443,6 +443,20 @@
     refs->mBase->onFirstRef();
 }
 
+void RefBase::incStrongRequireStrong(const void* id) const {
+    weakref_impl* const refs = mRefs;
+    refs->incWeak(id);
+
+    refs->addStrongRef(id);
+    const int32_t c = refs->mStrong.fetch_add(1, std::memory_order_relaxed);
+
+    LOG_ALWAYS_FATAL_IF(c <= 0 || c == INITIAL_STRONG_VALUE,
+                        "incStrongRequireStrong() called on %p which isn't already owned", refs);
+#if PRINT_REFS
+    ALOGD("incStrong (requiring strong) of %p from %p: cnt=%d\n", this, id, c);
+#endif
+}
+
 void RefBase::decStrong(const void* id) const
 {
     weakref_impl* const refs = mRefs;
@@ -521,6 +535,14 @@
     ALOG_ASSERT(c >= 0, "incWeak called on %p after last weak ref", this);
 }
 
+void RefBase::weakref_type::incWeakRequireWeak(const void* id)
+{
+    weakref_impl* const impl = static_cast<weakref_impl*>(this);
+    impl->addWeakRef(id);
+    const int32_t c __unused = impl->mWeak.fetch_add(1,
+            std::memory_order_relaxed);
+    LOG_ALWAYS_FATAL_IF(c <= 0, "incWeakRequireWeak called on %p which has no weak refs", this);
+}
 
 void RefBase::weakref_type::decWeak(const void* id)
 {
diff --git a/libutils/RefBase_test.cpp b/libutils/RefBase_test.cpp
index c9b4894..dcc469e 100644
--- a/libutils/RefBase_test.cpp
+++ b/libutils/RefBase_test.cpp
@@ -241,6 +241,30 @@
     ASSERT_FALSE(wp1 != wp2);
 }
 
+TEST(RefBase, AssertWeakRefExistsSuccess) {
+    // uses some other refcounting method, or non at all
+    bool isDeleted;
+    sp<Foo> foo = sp<Foo>::make(&isDeleted);
+    wp<Foo> weakFoo = foo;
+
+    EXPECT_EQ(weakFoo, wp<Foo>::fromExisting(foo.get()));
+
+    EXPECT_FALSE(isDeleted);
+    foo = nullptr;
+    EXPECT_TRUE(isDeleted);
+}
+
+TEST(RefBase, AssertWeakRefExistsDeath) {
+    // uses some other refcounting method, or non at all
+    bool isDeleted;
+    Foo* foo = new Foo(&isDeleted);
+
+    // can only get a valid wp<> object when you construct it from an sp<>
+    EXPECT_DEATH(wp<Foo>::fromExisting(foo), "");
+
+    delete foo;
+}
+
 // Set up a situation in which we race with visit2AndRremove() to delete
 // 2 strong references.  Bar destructor checks that there are no early
 // deletions and prior updates are visible to destructor.
diff --git a/libutils/StrongPointer_test.cpp b/libutils/StrongPointer_test.cpp
index d37c1de..29f6bd4 100644
--- a/libutils/StrongPointer_test.cpp
+++ b/libutils/StrongPointer_test.cpp
@@ -21,8 +21,8 @@
 
 using namespace android;
 
-class SPFoo : public LightRefBase<SPFoo> {
-public:
+class SPFoo : virtual public RefBase {
+  public:
     explicit SPFoo(bool* deleted_check) : mDeleted(deleted_check) {
         *mDeleted = false;
     }
@@ -69,3 +69,14 @@
     ASSERT_NE(nullptr, foo);
     ASSERT_NE(foo, nullptr);
 }
+
+TEST(StrongPointer, AssertStrongRefExists) {
+    // uses some other refcounting method, or non at all
+    bool isDeleted;
+    SPFoo* foo = new SPFoo(&isDeleted);
+
+    // can only get a valid sp<> object when you construct it as an sp<> object
+    EXPECT_DEATH(sp<SPFoo>::fromExisting(foo), "");
+
+    delete foo;
+}
diff --git a/libutils/include/utils/RefBase.h b/libutils/include/utils/RefBase.h
index e7acd17..5a5bd56 100644
--- a/libutils/include/utils/RefBase.h
+++ b/libutils/include/utils/RefBase.h
@@ -140,7 +140,9 @@
 // count, and accidentally passed to f(sp<T>), a strong pointer to the object
 // will be temporarily constructed and destroyed, prematurely deallocating the
 // object, and resulting in heap corruption. None of this would be easily
-// visible in the source.
+// visible in the source. See below on
+// ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION for a compile time
+// option which helps avoid this case.
 
 // Extra Features:
 
@@ -167,6 +169,42 @@
 // to THE SAME sp<> or wp<>.  In effect, their thread-safety properties are
 // exactly like those of T*, NOT atomic<T*>.
 
+// Safety option: ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION
+//
+// This flag makes the semantics for using a RefBase object with wp<> and sp<>
+// much stricter by disabling implicit conversion from raw pointers to these
+// objects. In order to use this, apply this flag in Android.bp like so:
+//
+//    cflags: [
+//        "-DANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION",
+//    ],
+//
+// REGARDLESS of whether this flag is on, best usage of sp<> is shown below. If
+// this flag is on, no other usage is possible (directly calling RefBase methods
+// is possible, but seeing code using 'incStrong' instead of 'sp<>', for
+// instance, should already set off big alarm bells. With carefully constructed
+// data structures, it should NEVER be necessary to directly use RefBase
+// methods). Proper RefBase usage:
+//
+//    class Foo : virtual public RefBase { ... };
+//
+//    // always construct an sp object with sp::make
+//    sp<Foo> myFoo = sp<Foo>::make(/*args*/);
+//
+//    // if you need a weak pointer, it must be constructed from a strong
+//    // pointer
+//    wp<Foo> weakFoo = myFoo; // NOT myFoo.get()
+//
+//    // If you are inside of a method of Foo and need access to a strong
+//    // explicitly call this function. This documents your intention to code
+//    // readers, and it will give a runtime error for what otherwise would
+//    // be potential double ownership
+//    .... Foo::someMethod(...) {
+//        // asserts if there is a memory issue
+//        sp<Foo> thiz = sp<Foo>::fromExisting(this);
+//    }
+//
+
 #ifndef ANDROID_REF_BASE_H
 #define ANDROID_REF_BASE_H
 
@@ -244,6 +282,7 @@
 {
 public:
             void            incStrong(const void* id) const;
+            void            incStrongRequireStrong(const void* id) const;
             void            decStrong(const void* id) const;
     
             void            forceIncStrong(const void* id) const;
@@ -257,6 +296,7 @@
         RefBase*            refBase() const;
 
         void                incWeak(const void* id);
+        void                incWeakRequireWeak(const void* id);
         void                decWeak(const void* id);
 
         // acquires a strong reference if there is already one.
@@ -365,10 +405,24 @@
 
     inline wp() : m_ptr(nullptr), m_refs(nullptr) { }
 
+    // if nullptr, returns nullptr
+    //
+    // if a weak pointer is already available, this will retrieve it,
+    // otherwise, this will abort
+    static inline wp<T> fromExisting(T* other);
+
+    // for more information about this flag, see above
+#if defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
+    wp(std::nullptr_t) : wp() {}
+#else
     wp(T* other);  // NOLINT(implicit)
+#endif
     wp(const wp<T>& other);
     explicit wp(const sp<T>& other);
+
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
     template<typename U> wp(U* other);  // NOLINT(implicit)
+#endif
     template<typename U> wp(const sp<U>& other);  // NOLINT(implicit)
     template<typename U> wp(const wp<U>& other);  // NOLINT(implicit)
 
@@ -376,11 +430,15 @@
 
     // Assignment
 
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
     wp& operator = (T* other);
+#endif
     wp& operator = (const wp<T>& other);
     wp& operator = (const sp<T>& other);
 
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
     template<typename U> wp& operator = (U* other);
+#endif
     template<typename U> wp& operator = (const wp<U>& other);
     template<typename U> wp& operator = (const sp<U>& other);
 
@@ -481,12 +539,26 @@
 // Note that the above comparison operations go out of their way to provide an ordering consistent
 // with ordinary pointer comparison; otherwise they could ignore m_ptr, and just compare m_refs.
 
+template <typename T>
+wp<T> wp<T>::fromExisting(T* other) {
+    if (!other) return nullptr;
+
+    auto refs = other->getWeakRefs();
+    refs->incWeakRequireWeak(other);
+
+    wp<T> ret;
+    ret.m_refs = refs;
+    return ret;
+}
+
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
 template<typename T>
 wp<T>::wp(T* other)
     : m_ptr(other)
 {
     m_refs = other ? m_refs = other->createWeak(this) : nullptr;
 }
+#endif
 
 template<typename T>
 wp<T>::wp(const wp<T>& other)
@@ -502,12 +574,14 @@
     m_refs = m_ptr ? m_ptr->createWeak(this) : nullptr;
 }
 
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
 template<typename T> template<typename U>
 wp<T>::wp(U* other)
     : m_ptr(other)
 {
     m_refs = other ? other->createWeak(this) : nullptr;
 }
+#endif
 
 template<typename T> template<typename U>
 wp<T>::wp(const wp<U>& other)
@@ -534,6 +608,7 @@
     if (m_ptr) m_refs->decWeak(this);
 }
 
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
 template<typename T>
 wp<T>& wp<T>::operator = (T* other)
 {
@@ -544,6 +619,7 @@
     m_refs = newRefs;
     return *this;
 }
+#endif
 
 template<typename T>
 wp<T>& wp<T>::operator = (const wp<T>& other)
@@ -569,6 +645,7 @@
     return *this;
 }
 
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
 template<typename T> template<typename U>
 wp<T>& wp<T>::operator = (U* other)
 {
@@ -579,6 +656,7 @@
     m_refs = newRefs;
     return *this;
 }
+#endif
 
 template<typename T> template<typename U>
 wp<T>& wp<T>::operator = (const wp<U>& other)
diff --git a/libutils/include/utils/StrongPointer.h b/libutils/include/utils/StrongPointer.h
index 11128f2..1f07052 100644
--- a/libutils/include/utils/StrongPointer.h
+++ b/libutils/include/utils/StrongPointer.h
@@ -32,16 +32,43 @@
 public:
     inline sp() : m_ptr(nullptr) { }
 
-    // TODO: switch everyone to using this over new, and make RefBase operator
-    // new private to that class so that we can avoid RefBase being used with
-    // other memory management mechanisms.
+    // The old way of using sp<> was like this. This is bad because it relies
+    // on implicit conversion to sp<>, which we would like to remove (if an
+    // object is being managed some other way, this is double-ownership). We
+    // want to move away from this:
+    //
+    //     sp<Foo> foo = new Foo(...); // DO NOT DO THIS
+    //
+    // Instead, prefer to do this:
+    //
+    //     sp<Foo> foo = sp<Foo>::make(...); // DO THIS
+    //
+    // Sometimes, in order to use this, when a constructor is marked as private,
+    // you may need to add this to your class:
+    //
+    //     friend class sp<Foo>;
     template <typename... Args>
     static inline sp<T> make(Args&&... args);
 
+    // if nullptr, returns nullptr
+    //
+    // if a strong pointer is already available, this will retrieve it,
+    // otherwise, this will abort
+    static inline sp<T> fromExisting(T* other);
+
+    // for more information about this macro and correct RefBase usage, see
+    // the comment at the top of utils/RefBase.h
+#if defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
+    sp(std::nullptr_t) : sp() {}
+#else
     sp(T* other);  // NOLINT(implicit)
+#endif
     sp(const sp<T>& other);
     sp(sp<T>&& other) noexcept;
+
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
     template<typename U> sp(U* other);  // NOLINT(implicit)
+#endif
     template<typename U> sp(const sp<U>& other);  // NOLINT(implicit)
     template<typename U> sp(sp<U>&& other);  // NOLINT(implicit)
 
@@ -49,13 +76,17 @@
 
     // Assignment
 
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
     sp& operator = (T* other);
+#endif
     sp& operator = (const sp<T>& other);
     sp& operator=(sp<T>&& other) noexcept;
 
     template<typename U> sp& operator = (const sp<U>& other);
     template<typename U> sp& operator = (sp<U>&& other);
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
     template<typename U> sp& operator = (U* other);
+#endif
 
     //! Special optimization for use by ProcessState (and nobody else).
     void force_set(T* other);
@@ -189,6 +220,19 @@
     return result;
 }
 
+template <typename T>
+sp<T> sp<T>::fromExisting(T* other) {
+    if (other) {
+        check_not_on_stack(other);
+        other->incStrongRequireStrong(other);
+        sp<T> result;
+        result.m_ptr = other;
+        return result;
+    }
+    return nullptr;
+}
+
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
 template<typename T>
 sp<T>::sp(T* other)
         : m_ptr(other) {
@@ -197,6 +241,7 @@
         other->incStrong(this);
     }
 }
+#endif
 
 template<typename T>
 sp<T>::sp(const sp<T>& other)
@@ -210,6 +255,7 @@
     other.m_ptr = nullptr;
 }
 
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
 template<typename T> template<typename U>
 sp<T>::sp(U* other)
         : m_ptr(other) {
@@ -218,6 +264,7 @@
         (static_cast<T*>(other))->incStrong(this);
     }
 }
+#endif
 
 template<typename T> template<typename U>
 sp<T>::sp(const sp<U>& other)
@@ -260,6 +307,7 @@
     return *this;
 }
 
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
 template<typename T>
 sp<T>& sp<T>::operator =(T* other) {
     T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
@@ -272,6 +320,7 @@
     m_ptr = other;
     return *this;
 }
+#endif
 
 template<typename T> template<typename U>
 sp<T>& sp<T>::operator =(const sp<U>& other) {
@@ -294,6 +343,7 @@
     return *this;
 }
 
+#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
 template<typename T> template<typename U>
 sp<T>& sp<T>::operator =(U* other) {
     T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
@@ -303,6 +353,7 @@
     m_ptr = other;
     return *this;
 }
+#endif
 
 template<typename T>
 void sp<T>::force_set(T* other) {