9fcbd5ed1d
Why I did it
fix possible cpld race read issue between watchdog and reboot cause
process
How I did it
Use fcntl.flock to limit parallel access to cpld sys file
How to verify it
It can be simulated and verified with following python script
``` python3
import fcntl
import signal
import threading
exit_flag = False
def get_cpld_reg_value(getreg_path, register):
file = open(getreg_path, 'w+')
# Acquire an exclusive lock on the file
fcntl.flock(file, fcntl.LOCK_EX)
try:
file.write(register + '\n')
file.flush()
# Seek to the beginning of the file
file.seek(0)
# Read the content of the file
result = file.readline().strip()
finally:
# Release the lock and close the file
fcntl.flock(file, fcntl.LOCK_UN)
file.close()
return result
def cpld_read(thread_num, cpld_reg, expect_val):
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}")
if val != expect_val:
print(f"Thread {thread_num}: get cpld reg {cpld_reg}, value
{val}, expect_val {expect_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', '0x11',))
t2 = threading.Thread(target=cpld_read, args=(2, '0x141', '0x00',))
t1.start()
t2.start()
t1.join()
t2.join()
```
98 lines
2.5 KiB
Python
98 lines
2.5 KiB
Python
import fcntl
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import os
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import struct
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import subprocess
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from mmap import *
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from sonic_py_common import device_info
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HOST_CHK_CMD = ["docker"]
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EMPTY_STRING = ""
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class APIHelper():
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def __init__(self):
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(self.platform, self.hwsku) = device_info.get_platform_and_hwsku()
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def is_host(self):
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try:
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subprocess.call(HOST_CHK_CMD, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
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except FileNotFoundError:
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return False
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return True
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def pci_get_value(self, resource, offset):
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status = True
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result = ""
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try:
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fd = os.open(resource, os.O_RDWR)
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mm = mmap(fd, 0)
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mm.seek(int(offset))
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read_data_stream = mm.read(4)
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result = struct.unpack('I', read_data_stream)
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except:
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status = False
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return status, result
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def run_command(self, cmd):
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status = True
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result = ""
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try:
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p = subprocess.Popen(
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cmd, universal_newlines=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
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raw_data, err = p.communicate()
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if err == '':
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result = raw_data.strip()
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except:
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status = False
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return status, result
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def read_txt_file(self, file_path):
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try:
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with open(file_path, 'r') as fd:
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data = fd.read()
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return data.strip()
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except IOError:
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pass
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return None
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def read_one_line_file(self, file_path):
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try:
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with open(file_path, 'r') as fd:
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data = fd.readline()
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return data.strip()
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except IOError:
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pass
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return None
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def write_txt_file(self, file_path, value):
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try:
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with open(file_path, 'w') as fd:
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fd.write(str(value))
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except Exception:
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return False
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return True
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def get_cpld_reg_value(self, getreg_path, register):
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file = open(getreg_path, 'w+')
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# Acquire an exclusive lock on the file
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fcntl.flock(file, fcntl.LOCK_EX)
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try:
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file.write(register + '\n')
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file.flush()
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# Seek to the beginning of the file
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file.seek(0)
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# Read the content of the file
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result = file.readline().strip()
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finally:
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# Release the lock and close the file
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fcntl.flock(file, fcntl.LOCK_UN)
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file.close()
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return result
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