From d633928a160ee029fa1a16f10e62f6628020aaef Mon Sep 17 00:00:00 2001
From: Dan Halbert <halbert@halwitz.org>
Date: Tue, 9 Apr 2019 20:23:01 -0400
Subject: [PATCH] Don't let a background task call run_background_tasks()

---
 main.c                            |  3 +++
 ports/atmel-samd/background.c     | 13 ++++++++++++
 ports/atmel-samd/background.h     |  1 +
 ports/nrf/background.c            | 12 +++++++++++
 ports/nrf/background.h            | 35 +++++++++++++++++++++++++++++++
 ports/nrf/supervisor/qspi_flash.c |  3 +--
 6 files changed, 65 insertions(+), 2 deletions(-)
 create mode 100644 ports/nrf/background.h

diff --git a/main.c b/main.c
index 77498d7dee..3b7e90a7a6 100755
--- a/main.c
+++ b/main.c
@@ -43,6 +43,7 @@
 #include "lib/mp-readline/readline.h"
 #include "lib/utils/pyexec.h"
 
+#include "background.h"
 #include "mpconfigboard.h"
 #include "shared-module/displayio/__init__.h"
 #include "supervisor/cpu.h"
@@ -86,6 +87,8 @@ void start_mp(supervisor_allocation* heap) {
     reset_status_led();
     autoreload_stop();
 
+    background_tasks_reset();
+
     // Stack limit should be less than real stack size, so we have a chance
     // to recover from limit hit.  (Limit is measured in bytes.)
     mp_stack_ctrl_init();
diff --git a/ports/atmel-samd/background.c b/ports/atmel-samd/background.c
index a8c4e38918..4e88d34e79 100644
--- a/ports/atmel-samd/background.c
+++ b/ports/atmel-samd/background.c
@@ -42,8 +42,20 @@ volatile uint64_t last_finished_tick = 0;
 
 bool stack_ok_so_far = true;
 
+static bool running_background_tasks = false;
+
+void background_tasks_reset(void) {
+    running_background_tasks = false;
+}
+
 void run_background_tasks(void) {
+    // Don't call ourselves recursively.
+    if (running_background_tasks) {
+        return;
+    }
     assert_heap_ok();
+    running_background_tasks = true;
+
     #if (defined(SAMD21) && defined(PIN_PA02)) || defined(SAMD51)
     audio_dma_background();
     #endif
@@ -56,6 +68,7 @@ void run_background_tasks(void) {
     #endif
     filesystem_background();
     usb_background();
+    running_background_tasks = false;
     assert_heap_ok();
 
     last_finished_tick = ticks_ms;
diff --git a/ports/atmel-samd/background.h b/ports/atmel-samd/background.h
index 8d1316e731..d9866a6abc 100644
--- a/ports/atmel-samd/background.h
+++ b/ports/atmel-samd/background.h
@@ -29,6 +29,7 @@
 
 #include <stdbool.h>
 
+void background_tasks_reset(void);
 void run_background_tasks(void);
 void run_background_vm_tasks(void);
 bool background_tasks_ok(void);
diff --git a/ports/nrf/background.c b/ports/nrf/background.c
index ea6e846b31..3fb5febd31 100644
--- a/ports/nrf/background.c
+++ b/ports/nrf/background.c
@@ -33,13 +33,25 @@
 #include "shared-module/displayio/__init__.h"
 #endif
 
+static bool running_background_tasks = false;
+
+void background_tasks_reset(void) {
+    running_background_tasks = false;
+}
+
 void run_background_tasks(void) {
+    // Don't call ourselves recursively.
+    if (running_background_tasks) {
+        return;
+    }
+    running_background_tasks = true;
     filesystem_background();
     usb_background();
 
     #ifdef CIRCUITPY_DISPLAYIO
     displayio_refresh_displays();
     #endif
+    running_background_tasks = false;
 
     assert_heap_ok();
 }
diff --git a/ports/nrf/background.h b/ports/nrf/background.h
new file mode 100644
index 0000000000..d53681c0fd
--- /dev/null
+++ b/ports/nrf/background.h
@@ -0,0 +1,35 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Dan Halbert for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_NRF_BACKGROUND_H
+#define MICROPY_INCLUDED_NRF_BACKGROUND_H
+
+#include <stdbool.h>
+
+void background_tasks_reset(void);
+void run_background_tasks(void);
+
+#endif  // MICROPY_INCLUDED_NRF_BACKGROUND_H
diff --git a/ports/nrf/supervisor/qspi_flash.c b/ports/nrf/supervisor/qspi_flash.c
index 51a9ec0329..bb449d881c 100644
--- a/ports/nrf/supervisor/qspi_flash.c
+++ b/ports/nrf/supervisor/qspi_flash.c
@@ -47,8 +47,7 @@ bool spi_flash_command(uint8_t command) {
         .wipwait = false,
         .wren = false
     };
-    nrfx_qspi_cinstr_xfer(&cinstr_cfg, NULL, NULL);
-    return true;
+    return nrfx_qspi_cinstr_xfer(&cinstr_cfg, NULL, NULL) == NRFX_SUCCESS;
 }
 
 bool spi_flash_read_command(uint8_t command, uint8_t* response, uint32_t length) {