Fix for 06-Mutex Challenge Solution

[morgoob]

Pull Request Description

Issue

The blinkLED task calls xSemaphoreGive(mutex) without having acquired the mutex using xSemaphoreTake(mutex, portMAX_DELAY) first, causing a system reboot (due to failed assertion) after the delay value is entered by a user.

Output

Here is the output of the original solution:

---FreeRTOS Mutex Solution---
Enter a number for delay (milliseconds)
Sending: 50

assert failed: xQueueGenericSend queue.c:832 (pxQueue->pcHead != ((void *)0) || pxQueue->u.xSemaphore.xMutexHolder == ((void *)0) || pxQueue->u.xSemaphore.xMutexHolder == xTaskGetCurrentTaskHandle())

assert failed: xQueueGenericSend queue.c:832 (pxQueue->pcHead != ((void *)0) || pxQueue->u.xSemaphore.xMutexHolder == ((void *)0) || pxQueue->u.xSemaphore.xMutexHolder == xTaskGetCurrentTaskHandle())


Backtrace: 0x400881a7:0x3ffbb0a0 0x400833dc:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 0x400881a7:0x3ffbb160 0x400881a7:0x3ffbb180 0x400881a7:0x3ffbb1f0 0x4008007d:0x3ffbb0a0 0x40082ff1:0x3ffbb0c0 0x400881a7:0x3ffbb0e0 0x400881a7:0x3ffbb110 0x400881a7:0x3ffbb140 |<-CONTINUES

ELF file SHA256: 42aaf96fb649f818

Rebooting...
ets Jul 29 2019 12:21:46

rst:0xc (SW_CPU_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0030,len:1184
load:0x40078000,len:13260
load:0x40080400,len:3028
entry 0x400805e4

Here is the output with my fix:

---FreeRTOS Mutex Solution---
Enter a number for delay (milliseconds)
Sending: 250
Received: 250
Done!