Merge branch 'master' into cmake-export-fix

7 files changed, 60 insertions, 99 deletions

diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc
index 272b3617b2..eb5ced4c20 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc
@@ -106,6 +106,8 @@
 #include "src/core/lib/backoff/backoff.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/channel_stack.h"
+#include "src/core/lib/gpr++/manual_constructor.h"
+#include "src/core/lib/gpr/string.h"
 #include "src/core/lib/iomgr/combiner.h"
 #include "src/core/lib/iomgr/sockaddr.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
@@ -113,8 +115,6 @@
 #include "src/core/lib/slice/slice_hash_table.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
-#include "src/core/lib/support/manual_constructor.h"
-#include "src/core/lib/support/string.h"
 #include "src/core/lib/surface/call.h"
 #include "src/core/lib/surface/channel.h"
 #include "src/core/lib/surface/channel_init.h"
@@ -939,7 +939,7 @@ static void glb_shutdown_locked(grpc_lb_policy* pol,
       }
       gpr_free(pp);
     } else {
-      pp->pick->connected_subchannel = nullptr;
+      pp->pick->connected_subchannel.reset();
       GRPC_CLOSURE_SCHED(&pp->on_complete, GRPC_ERROR_REF(error));
     }
     pp = next;
@@ -976,7 +976,7 @@ static void glb_cancel_pick_locked(grpc_lb_policy* pol,
   while (pp != nullptr) {
     pending_pick* next = pp->next;
     if (pp->pick == pick) {
-      pick->connected_subchannel = nullptr;
+      pick->connected_subchannel.reset();
       GRPC_CLOSURE_SCHED(&pp->on_complete,
                          GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
                              "Pick Cancelled", &error, 1));
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.cc b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.cc
index a8ecea4212..1e7f34bdc7 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.cc
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.cc
@@ -22,8 +22,8 @@
 #include "src/core/ext/filters/client_channel/client_channel.h"
 #include "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h"
 #include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/gpr/string.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
-#include "src/core/lib/support/string.h"
 
 grpc_channel* grpc_lb_policy_grpclb_create_lb_channel(
     const char* lb_service_target_addresses,
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc
index 76bcddf945..15233d371c 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc
@@ -22,11 +22,11 @@
 #include "src/core/ext/filters/client_channel/client_channel.h"
 #include "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h"
 #include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/gpr/string.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/security/credentials/credentials.h"
 #include "src/core/lib/security/transport/lb_targets_info.h"
 #include "src/core/lib/slice/slice_internal.h"
-#include "src/core/lib/support/string.h"
 
 grpc_channel* grpc_lb_policy_grpclb_create_lb_channel(
     const char* lb_service_target_addresses,
diff --git a/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc b/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
index 60385272cf..725b78d478 100644
--- a/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
+++ b/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
@@ -81,7 +81,7 @@ static void pf_shutdown_locked(grpc_lb_policy* pol,
         GRPC_CLOSURE_SCHED(pick->on_complete, GRPC_ERROR_NONE);
       }
     } else {
-      pick->connected_subchannel = nullptr;
+      pick->connected_subchannel.reset();
       GRPC_CLOSURE_SCHED(pick->on_complete, GRPC_ERROR_REF(error));
     }
   }
@@ -111,7 +111,7 @@ static void pf_cancel_pick_locked(grpc_lb_policy* pol,
   while (pp != nullptr) {
     grpc_lb_policy_pick_state* next = pp->next;
     if (pp == pick) {
-      pick->connected_subchannel = nullptr;
+      pick->connected_subchannel.reset();
       GRPC_CLOSURE_SCHED(pick->on_complete,
                          GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
                              "Pick Cancelled", &error, 1));
@@ -176,8 +176,7 @@ static int pf_pick_locked(grpc_lb_policy* pol,
   pick_first_lb_policy* p = (pick_first_lb_policy*)pol;
   // If we have a selected subchannel already, return synchronously.
   if (p->selected != nullptr) {
-    pick->connected_subchannel = GRPC_CONNECTED_SUBCHANNEL_REF(
-        p->selected->connected_subchannel, "picked");
+    pick->connected_subchannel = p->selected->connected_subchannel;
     return 1;
   }
   // No subchannel selected yet, so handle asynchronously.
@@ -217,8 +216,7 @@ static void pf_ping_one_locked(grpc_lb_policy* pol, grpc_closure* on_initiate,
                                grpc_closure* on_ack) {
   pick_first_lb_policy* p = (pick_first_lb_policy*)pol;
   if (p->selected) {
-    grpc_connected_subchannel_ping(p->selected->connected_subchannel,
-                                   on_initiate, on_ack);
+    p->selected->connected_subchannel->Ping(on_initiate, on_ack);
   } else {
     GRPC_CLOSURE_SCHED(on_initiate,
                        GRPC_ERROR_CREATE_FROM_STATIC_STRING("Not connected"));
@@ -297,8 +295,7 @@ static void pf_update_locked(grpc_lb_policy* policy,
                   subchannel_list->num_subchannels);
         }
         if (p->selected->connected_subchannel != nullptr) {
-          sd->connected_subchannel = GRPC_CONNECTED_SUBCHANNEL_REF(
-              p->selected->connected_subchannel, "pf_update_includes_selected");
+          sd->connected_subchannel = p->selected->connected_subchannel;
         }
         p->selected = sd;
         if (p->subchannel_list != nullptr) {
@@ -410,8 +407,8 @@ static void pf_connectivity_changed_locked(void* arg, grpc_error* error) {
       // re-resolution is introduced. But we need to investigate whether we
       // really want to take any action instead of waiting for the selected
       // subchannel reconnecting.
-      if (sd->curr_connectivity_state == GRPC_CHANNEL_SHUTDOWN ||
-          sd->curr_connectivity_state == GRPC_CHANNEL_TRANSIENT_FAILURE) {
+      GPR_ASSERT(sd->curr_connectivity_state != GRPC_CHANNEL_SHUTDOWN);
+      if (sd->curr_connectivity_state == GRPC_CHANNEL_TRANSIENT_FAILURE) {
         // If the selected channel goes bad, request a re-resolution.
         grpc_connectivity_state_set(&p->state_tracker, GRPC_CHANNEL_IDLE,
                                     GRPC_ERROR_NONE,
@@ -419,20 +416,19 @@ static void pf_connectivity_changed_locked(void* arg, grpc_error* error) {
         p->started_picking = false;
         grpc_lb_policy_try_reresolve(&p->base, &grpc_lb_pick_first_trace,
                                      GRPC_ERROR_NONE);
+        // in transient failure. Rely on re-resolution to recover.
+        p->selected = nullptr;
+        grpc_lb_subchannel_data_stop_connectivity_watch(sd);
+        grpc_lb_subchannel_list_unref_for_connectivity_watch(
+            sd->subchannel_list, "pf_selected_shutdown");
+        grpc_lb_subchannel_data_unref_subchannel(
+            sd, "pf_selected_shutdown");  // Unrefs connected subchannel
       } else {
         grpc_connectivity_state_set(&p->state_tracker,
                                     sd->curr_connectivity_state,
                                     GRPC_ERROR_REF(error), "selected_changed");
-      }
-      if (sd->curr_connectivity_state != GRPC_CHANNEL_SHUTDOWN) {
         // Renew notification.
         grpc_lb_subchannel_data_start_connectivity_watch(sd);
-      } else {
-        p->selected = nullptr;
-        grpc_lb_subchannel_data_stop_connectivity_watch(sd);
-        grpc_lb_subchannel_list_unref_for_connectivity_watch(
-            sd->subchannel_list, "pf_selected_shutdown");
-        grpc_lb_subchannel_data_unref_subchannel(sd, "pf_selected_shutdown");
       }
     }
     return;
@@ -450,6 +446,8 @@ static void pf_connectivity_changed_locked(void* arg, grpc_error* error) {
     case GRPC_CHANNEL_READY: {
       // Case 2.  Promote p->latest_pending_subchannel_list to
       // p->subchannel_list.
+      sd->connected_subchannel =
+          grpc_subchannel_get_connected_subchannel(sd->subchannel);
       if (sd->subchannel_list == p->latest_pending_subchannel_list) {
         GPR_ASSERT(p->subchannel_list != nullptr);
         grpc_lb_subchannel_list_shutdown_and_unref(p->subchannel_list,
@@ -460,9 +458,6 @@ static void pf_connectivity_changed_locked(void* arg, grpc_error* error) {
       // Cases 1 and 2.
       grpc_connectivity_state_set(&p->state_tracker, GRPC_CHANNEL_READY,
                                   GRPC_ERROR_NONE, "connecting_ready");
-      sd->connected_subchannel = GRPC_CONNECTED_SUBCHANNEL_REF(
-          grpc_subchannel_get_connected_subchannel(sd->subchannel),
-          "connected");
       p->selected = sd;
       if (grpc_lb_pick_first_trace.enabled()) {
         gpr_log(GPR_INFO, "Pick First %p selected subchannel %p", (void*)p,
@@ -474,8 +469,7 @@ static void pf_connectivity_changed_locked(void* arg, grpc_error* error) {
       grpc_lb_policy_pick_state* pick;
       while ((pick = p->pending_picks)) {
         p->pending_picks = pick->next;
-        pick->connected_subchannel = GRPC_CONNECTED_SUBCHANNEL_REF(
-            p->selected->connected_subchannel, "picked");
+        pick->connected_subchannel = p->selected->connected_subchannel;
         if (grpc_lb_pick_first_trace.enabled()) {
           gpr_log(GPR_INFO,
                   "Servicing pending pick with selected subchannel %p",
@@ -520,39 +514,8 @@ static void pf_connectivity_changed_locked(void* arg, grpc_error* error) {
       grpc_lb_subchannel_data_start_connectivity_watch(sd);
       break;
     }
-    case GRPC_CHANNEL_SHUTDOWN: {
-      grpc_lb_subchannel_data_stop_connectivity_watch(sd);
-      grpc_lb_subchannel_data_unref_subchannel(sd, "pf_candidate_shutdown");
-      // Advance to next subchannel and check its state.
-      grpc_lb_subchannel_data* original_sd = sd;
-      do {
-        sd->subchannel_list->checking_subchannel =
-            (sd->subchannel_list->checking_subchannel + 1) %
-            sd->subchannel_list->num_subchannels;
-        sd = &sd->subchannel_list
-                  ->subchannels[sd->subchannel_list->checking_subchannel];
-      } while (sd->subchannel == nullptr && sd != original_sd);
-      if (sd == original_sd) {
-        grpc_lb_subchannel_list_unref_for_connectivity_watch(
-            sd->subchannel_list, "pf_exhausted_subchannels");
-        if (sd->subchannel_list == p->subchannel_list) {
-          grpc_connectivity_state_set(&p->state_tracker, GRPC_CHANNEL_IDLE,
-                                      GRPC_ERROR_NONE,
-                                      "exhausted_subchannels+reresolve");
-          p->started_picking = false;
-          grpc_lb_policy_try_reresolve(&p->base, &grpc_lb_pick_first_trace,
-                                       GRPC_ERROR_NONE);
-        }
-      } else {
-        if (sd->subchannel_list == p->subchannel_list) {
-          grpc_connectivity_state_set(
-              &p->state_tracker, GRPC_CHANNEL_TRANSIENT_FAILURE,
-              GRPC_ERROR_REF(error), "subchannel_failed");
-        }
-        // Reuses the connectivity refs from the previous watch.
-        grpc_lb_subchannel_data_start_connectivity_watch(sd);
-      }
-    }
+    case GRPC_CHANNEL_SHUTDOWN:
+      GPR_UNREACHABLE_CODE(break);
   }
 }
 
diff --git a/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc b/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
index 92c7d5bd5d..e217a0b0c0 100644
--- a/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
+++ b/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
@@ -34,6 +34,7 @@
 #include "src/core/ext/filters/client_channel/subchannel_index.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/debug/trace.h"
+#include "src/core/lib/gpr++/ref_counted_ptr.h"
 #include "src/core/lib/iomgr/combiner.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/transport/connectivity_state.h"
@@ -127,7 +128,7 @@ static void update_last_ready_subchannel_index_locked(round_robin_lb_policy* p,
             (void*)p, (unsigned long)last_ready_index,
             (void*)p->subchannel_list->subchannels[last_ready_index].subchannel,
             (void*)p->subchannel_list->subchannels[last_ready_index]
-                .connected_subchannel);
+                .connected_subchannel.get());
   }
 }
 
@@ -162,7 +163,7 @@ static void rr_shutdown_locked(grpc_lb_policy* pol,
         GRPC_CLOSURE_SCHED(pick->on_complete, GRPC_ERROR_NONE);
       }
     } else {
-      pick->connected_subchannel = nullptr;
+      pick->connected_subchannel.reset();
       GRPC_CLOSURE_SCHED(pick->on_complete, GRPC_ERROR_REF(error));
     }
   }
@@ -192,7 +193,7 @@ static void rr_cancel_pick_locked(grpc_lb_policy* pol,
   while (pp != nullptr) {
     grpc_lb_policy_pick_state* next = pp->next;
     if (pp == pick) {
-      pick->connected_subchannel = nullptr;
+      pick->connected_subchannel.reset();
       GRPC_CLOSURE_SCHED(pick->on_complete,
                          GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
                              "Pick cancelled", &error, 1));
@@ -216,7 +217,7 @@ static void rr_cancel_picks_locked(grpc_lb_policy* pol,
     grpc_lb_policy_pick_state* next = pick->next;
     if ((pick->initial_metadata_flags & initial_metadata_flags_mask) ==
         initial_metadata_flags_eq) {
-      pick->connected_subchannel = nullptr;
+      pick->connected_subchannel.reset();
       GRPC_CLOSURE_SCHED(pick->on_complete,
                          GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
                              "Pick cancelled", &error, 1));
@@ -262,8 +263,7 @@ static int rr_pick_locked(grpc_lb_policy* pol,
       /* readily available, report right away */
       grpc_lb_subchannel_data* sd =
           &p->subchannel_list->subchannels[next_ready_index];
-      pick->connected_subchannel =
-          GRPC_CONNECTED_SUBCHANNEL_REF(sd->connected_subchannel, "rr_picked");
+      pick->connected_subchannel = sd->connected_subchannel;
       if (pick->user_data != nullptr) {
         *pick->user_data = sd->user_data;
       }
@@ -272,8 +272,8 @@ static int rr_pick_locked(grpc_lb_policy* pol,
             GPR_DEBUG,
             "[RR %p] Picked target <-- Subchannel %p (connected %p) (sl %p, "
             "index %" PRIuPTR ")",
-            p, sd->subchannel, pick->connected_subchannel, sd->subchannel_list,
-            next_ready_index);
+            p, sd->subchannel, pick->connected_subchannel.get(),
+            sd->subchannel_list, next_ready_index);
       }
       /* only advance the last picked pointer if the selection was used */
       update_last_ready_subchannel_index_locked(p, next_ready_index);
@@ -291,15 +291,14 @@ static int rr_pick_locked(grpc_lb_policy* pol,
 
 static void update_state_counters_locked(grpc_lb_subchannel_data* sd) {
   grpc_lb_subchannel_list* subchannel_list = sd->subchannel_list;
+  GPR_ASSERT(sd->prev_connectivity_state != GRPC_CHANNEL_SHUTDOWN);
+  GPR_ASSERT(sd->curr_connectivity_state != GRPC_CHANNEL_SHUTDOWN);
   if (sd->prev_connectivity_state == GRPC_CHANNEL_READY) {
     GPR_ASSERT(subchannel_list->num_ready > 0);
     --subchannel_list->num_ready;
   } else if (sd->prev_connectivity_state == GRPC_CHANNEL_TRANSIENT_FAILURE) {
     GPR_ASSERT(subchannel_list->num_transient_failures > 0);
     --subchannel_list->num_transient_failures;
-  } else if (sd->prev_connectivity_state == GRPC_CHANNEL_SHUTDOWN) {
-    GPR_ASSERT(subchannel_list->num_shutdown > 0);
-    --subchannel_list->num_shutdown;
   } else if (sd->prev_connectivity_state == GRPC_CHANNEL_IDLE) {
     GPR_ASSERT(subchannel_list->num_idle > 0);
     --subchannel_list->num_idle;
@@ -309,8 +308,6 @@ static void update_state_counters_locked(grpc_lb_subchannel_data* sd) {
     ++subchannel_list->num_ready;
   } else if (sd->curr_connectivity_state == GRPC_CHANNEL_TRANSIENT_FAILURE) {
     ++subchannel_list->num_transient_failures;
-  } else if (sd->curr_connectivity_state == GRPC_CHANNEL_SHUTDOWN) {
-    ++subchannel_list->num_shutdown;
   } else if (sd->curr_connectivity_state == GRPC_CHANNEL_IDLE) {
     ++subchannel_list->num_idle;
   }
@@ -410,6 +407,7 @@ static void rr_connectivity_changed_locked(void* arg, grpc_error* error) {
   // either the current or latest pending subchannel lists.
   GPR_ASSERT(sd->subchannel_list == p->subchannel_list ||
              sd->subchannel_list == p->latest_pending_subchannel_list);
+  GPR_ASSERT(sd->pending_connectivity_state_unsafe != GRPC_CHANNEL_SHUTDOWN);
   // Now that we're inside the combiner, copy the pending connectivity
   // state (which was set by the connectivity state watcher) to
   // curr_connectivity_state, which is what we use inside of the combiner.
@@ -417,18 +415,17 @@ static void rr_connectivity_changed_locked(void* arg, grpc_error* error) {
   // Update state counters and new overall state.
   update_state_counters_locked(sd);
   update_lb_connectivity_status_locked(sd, GRPC_ERROR_REF(error));
-  // If the sd's new state is SHUTDOWN, unref the subchannel.
-  if (sd->curr_connectivity_state == GRPC_CHANNEL_SHUTDOWN) {
-    grpc_lb_subchannel_data_stop_connectivity_watch(sd);
-    grpc_lb_subchannel_data_unref_subchannel(sd, "rr_connectivity_shutdown");
-    grpc_lb_subchannel_list_unref_for_connectivity_watch(
-        sd->subchannel_list, "rr_connectivity_shutdown");
-  } else {  // sd not in SHUTDOWN
-    if (sd->curr_connectivity_state == GRPC_CHANNEL_READY) {
+  // If the sd's new state is TRANSIENT_FAILURE, unref the *connected*
+  // subchannel, if any.
+  switch (sd->curr_connectivity_state) {
+    case GRPC_CHANNEL_TRANSIENT_FAILURE: {
+      sd->connected_subchannel.reset();
+      break;
+    }
+    case GRPC_CHANNEL_READY: {
       if (sd->connected_subchannel == nullptr) {
-        sd->connected_subchannel = GRPC_CONNECTED_SUBCHANNEL_REF(
-            grpc_subchannel_get_connected_subchannel(sd->subchannel),
-            "connected");
+        sd->connected_subchannel =
+            grpc_subchannel_get_connected_subchannel(sd->subchannel);
       }
       if (sd->subchannel_list != p->subchannel_list) {
         // promote sd->subchannel_list to p->subchannel_list.
@@ -471,8 +468,7 @@ static void rr_connectivity_changed_locked(void* arg, grpc_error* error) {
       grpc_lb_policy_pick_state* pick;
       while ((pick = p->pending_picks)) {
         p->pending_picks = pick->next;
-        pick->connected_subchannel = GRPC_CONNECTED_SUBCHANNEL_REF(
-            selected->connected_subchannel, "rr_picked");
+        pick->connected_subchannel = selected->connected_subchannel;
         if (pick->user_data != nullptr) {
           *pick->user_data = selected->user_data;
         }
@@ -485,10 +481,15 @@ static void rr_connectivity_changed_locked(void* arg, grpc_error* error) {
         }
         GRPC_CLOSURE_SCHED(pick->on_complete, GRPC_ERROR_NONE);
       }
+      break;
     }
-    // Renew notification.
-    grpc_lb_subchannel_data_start_connectivity_watch(sd);
+    case GRPC_CHANNEL_SHUTDOWN:
+      GPR_UNREACHABLE_CODE(return );
+    case GRPC_CHANNEL_CONNECTING:
+    case GRPC_CHANNEL_IDLE:;  // fallthrough
   }
+  // Renew notification.
+  grpc_lb_subchannel_data_start_connectivity_watch(sd);
 }
 
 static grpc_connectivity_state rr_check_connectivity_locked(
@@ -512,10 +513,9 @@ static void rr_ping_one_locked(grpc_lb_policy* pol, grpc_closure* on_initiate,
   if (next_ready_index < p->subchannel_list->num_subchannels) {
     grpc_lb_subchannel_data* selected =
         &p->subchannel_list->subchannels[next_ready_index];
-    grpc_connected_subchannel* target = GRPC_CONNECTED_SUBCHANNEL_REF(
-        selected->connected_subchannel, "rr_ping");
-    grpc_connected_subchannel_ping(target, on_initiate, on_ack);
-    GRPC_CONNECTED_SUBCHANNEL_UNREF(target, "rr_ping");
+    grpc_core::RefCountedPtr<grpc_core::ConnectedSubchannel> target =
+        selected->connected_subchannel;
+    target->Ping(on_initiate, on_ack);
   } else {
     GRPC_CLOSURE_SCHED(on_initiate, GRPC_ERROR_CREATE_FROM_STATIC_STRING(
                                         "Round Robin not connected"));
diff --git a/src/core/ext/filters/client_channel/lb_policy/subchannel_list.cc b/src/core/ext/filters/client_channel/lb_policy/subchannel_list.cc
index 5ce1298afc..fa2ffcc796 100644
--- a/src/core/ext/filters/client_channel/lb_policy/subchannel_list.cc
+++ b/src/core/ext/filters/client_channel/lb_policy/subchannel_list.cc
@@ -42,10 +42,7 @@ void grpc_lb_subchannel_data_unref_subchannel(grpc_lb_subchannel_data* sd,
     }
     GRPC_SUBCHANNEL_UNREF(sd->subchannel, reason);
     sd->subchannel = nullptr;
-    if (sd->connected_subchannel != nullptr) {
-      GRPC_CONNECTED_SUBCHANNEL_UNREF(sd->connected_subchannel, reason);
-      sd->connected_subchannel = nullptr;
-    }
+    sd->connected_subchannel.reset();
     if (sd->user_data != nullptr) {
       GPR_ASSERT(sd->user_data_vtable != nullptr);
       sd->user_data_vtable->destroy(sd->user_data);
diff --git a/src/core/ext/filters/client_channel/lb_policy/subchannel_list.h b/src/core/ext/filters/client_channel/lb_policy/subchannel_list.h
index 0f8cea9347..f4e345def6 100644
--- a/src/core/ext/filters/client_channel/lb_policy/subchannel_list.h
+++ b/src/core/ext/filters/client_channel/lb_policy/subchannel_list.h
@@ -22,6 +22,7 @@
 #include "src/core/ext/filters/client_channel/lb_policy_registry.h"
 #include "src/core/ext/filters/client_channel/subchannel.h"
 #include "src/core/lib/debug/trace.h"
+#include "src/core/lib/gpr++/ref_counted_ptr.h"
 #include "src/core/lib/transport/connectivity_state.h"
 
 // TODO(roth): This code is intended to be shared between pick_first and
@@ -43,7 +44,7 @@ typedef struct {
   grpc_lb_subchannel_list* subchannel_list;
   /** subchannel itself */
   grpc_subchannel* subchannel;
-  grpc_connected_subchannel* connected_subchannel;
+  grpc_core::RefCountedPtr<grpc_core::ConnectedSubchannel> connected_subchannel;
   /** Is a connectivity notification pending? */
   bool connectivity_notification_pending;
   /** notification that connectivity has changed on subchannel */