#### Why I did it
fix possible cpld race read issue between watchdog and reboot cause process
##### Work item tracking
- Microsoft ADO **(number only)**:
#### How I did it
Use flock to limit parallel access to cpld sys file
#### How to verify it
It can be simulate and verified with following python script
```python3
import signal
import subprocess
import threading
exit_flag = False
def run_command(cmd):
status = True
result = ""
try:
p = subprocess.Popen(
cmd, shell=True, universal_newlines=True,
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
raw_data, err = p.communicate()
if err == '':
result = raw_data.strip()
except:
status = False
return status, result
def get_cpld_reg_value(getreg_path, register):
#cmd = "echo {1} > {0}; cat {0}".format(getreg_path, register)
cmd = "flock {0} -c 'echo {1} > {0}; cat {0}'".format(getreg_path,
register)
status, result = run_command(cmd)
return result if status else None
def cpld_read(thread_num, cpld_reg):
while not exit_flag:
val
= get_cpld_reg_value("/sys/devices/platform/dx010_cpld/getreg",
cpld_reg)
print(f"Thread {thread_num}: get cpld reg {cpld_reg}, value
{val}")
def signal_handler(sig, frame):
global exit_flag
print("Ctrl+C detected. Quitting...")
exit_flag = True
if __name__ == '__main__':
# Register the signal handler for Ctrl+C
signal.signal(signal.SIGINT, signal_handler)
t1 = threading.Thread(target=cpld_read, args=(1, '0x103',))
t2 = threading.Thread(target=cpld_read, args=(2, '0x141',))
t1.start()
t2.start()
t1.join()
t2.join()
```
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