Revert "adb: close ep0 on disconnection."

This reverts commit 69e97e4bee9ee43ef55d1bb205bc4ca065d089bc.

Bug: 28932120
Change-Id: I5e2569abed316c089886556c432bfe59bca08549
diff --git a/adb/usb_linux_client.cpp b/adb/usb_linux_client.cpp
index c10b48c..0ba6b4b 100644
--- a/adb/usb_linux_client.cpp
+++ b/adb/usb_linux_client.cpp
@@ -400,33 +400,35 @@
     v2_descriptor.os_header = os_desc_header;
     v2_descriptor.os_desc = os_desc_compat;
 
-    D("OPENING %s", USB_FFS_ADB_EP0);
-    h->control = adb_open(USB_FFS_ADB_EP0, O_RDWR);
-    if (h->control < 0) {
-        D("[ %s: cannot open control endpoint: errno=%d]", USB_FFS_ADB_EP0, errno);
-        goto err;
-    }
-
-    ret = adb_write(h->control, &v2_descriptor, sizeof(v2_descriptor));
-    if (ret < 0) {
-        v1_descriptor.header.magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC);
-        v1_descriptor.header.length = cpu_to_le32(sizeof(v1_descriptor));
-        v1_descriptor.header.fs_count = 3;
-        v1_descriptor.header.hs_count = 3;
-        v1_descriptor.fs_descs = fs_descriptors;
-        v1_descriptor.hs_descs = hs_descriptors;
-        D("[ %s: Switching to V1_descriptor format errno=%d ]", USB_FFS_ADB_EP0, errno);
-        ret = adb_write(h->control, &v1_descriptor, sizeof(v1_descriptor));
-        if (ret < 0) {
-            D("[ %s: write descriptors failed: errno=%d ]", USB_FFS_ADB_EP0, errno);
+    if (h->control < 0) { // might have already done this before
+        D("OPENING %s", USB_FFS_ADB_EP0);
+        h->control = adb_open(USB_FFS_ADB_EP0, O_RDWR);
+        if (h->control < 0) {
+            D("[ %s: cannot open control endpoint: errno=%d]", USB_FFS_ADB_EP0, errno);
             goto err;
         }
-    }
 
-    ret = adb_write(h->control, &strings, sizeof(strings));
-    if (ret < 0) {
-        D("[ %s: writing strings failed: errno=%d]", USB_FFS_ADB_EP0, errno);
-        goto err;
+        ret = adb_write(h->control, &v2_descriptor, sizeof(v2_descriptor));
+        if (ret < 0) {
+            v1_descriptor.header.magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC);
+            v1_descriptor.header.length = cpu_to_le32(sizeof(v1_descriptor));
+            v1_descriptor.header.fs_count = 3;
+            v1_descriptor.header.hs_count = 3;
+            v1_descriptor.fs_descs = fs_descriptors;
+            v1_descriptor.hs_descs = hs_descriptors;
+            D("[ %s: Switching to V1_descriptor format errno=%d ]", USB_FFS_ADB_EP0, errno);
+            ret = adb_write(h->control, &v1_descriptor, sizeof(v1_descriptor));
+            if (ret < 0) {
+                D("[ %s: write descriptors failed: errno=%d ]", USB_FFS_ADB_EP0, errno);
+                goto err;
+            }
+        }
+
+        ret = adb_write(h->control, &strings, sizeof(strings));
+        if (ret < 0) {
+            D("[ %s: writing strings failed: errno=%d]", USB_FFS_ADB_EP0, errno);
+            goto err;
+        }
     }
 
     h->bulk_out = adb_open(USB_FFS_ADB_OUT, O_RDWR);
@@ -554,7 +556,6 @@
     h->kicked = false;
     adb_close(h->bulk_out);
     adb_close(h->bulk_in);
-    adb_close(h->control);
     // Notify usb_adb_open_thread to open a new connection.
     adb_mutex_lock(&h->lock);
     h->open_new_connection = true;