我有一个打印数据结构的代码。
void
print_wheel_timer(wheel_timer_t *wt){
<code to print data structure>
}
Then i sandwiched the code in-between lock and unlock mutex calls.
void
print_wheel_timer(wheel_timer_t *wt){
pthread_mutex_lock(&wt->global_lock);
<code to print data structure>
pthread_mutex_unlock(&wt->global_lock);
}
现在,它是赛格法特。
我已经禁用了代码中的所有线程,现在程序是单线程的,仍然是segfault。
我正在使用gcc,ubuntu 19.04。
gdb展会
pthread_mutex_lock()
调用正在破坏数据结构!!真奇怪!
我将监视点放在由任意值写入的地址上,它显示对
pthread_mutex_lock()
正在修改它。当我移除这些锁定/解锁呼叫时,没有看到segfault。
(gdb) watch *(glthread_t *)&(wt->slotlist[1].slots.right)
Hardware watchpoint 2: *(glthread_t *)&(wt->slotlist[1].slots.right)
(gdb) c
Continuing.
Printing Wheel Timer DS
Thread 1 "test.exe" hit Hardware watchpoint 2: *(glthread_t *)&(wt->slotlist[1].slots.right)
Old value = {left = 0x0, right = 0x0}
New value = {left = 0x1, right = 0x0} <<< corruption !!
0x00007ffff7fa3934 in __GI___pthread_mutex_lock (mutex=0x5555555771d8)
at ../nptl/pthread_mutex_lock.c:80
80 ../nptl/pthread_mutex_lock.c: No such file or directory.
(gdb) bt
#0 0x00007ffff7fa3934 in __GI___pthread_mutex_lock (mutex=0x5555555771d8)
at ../nptl/pthread_mutex_lock.c:80
#1 0x000055555555f3a2 in print_wheel_timer (wt=0x555555577180)
at WheelTimer/WheelTimer.c:276
Code :
========
void
print_wheel_timer(wheel_timer_t *wt){
int i = 0, j = 0;
glthread_t *curr;
glthread_t *slot_list_head = NULL;
wheel_timer_elem_t *wt_elem = NULL;
printf("Printing Wheel Timer DS\n");
pthread_mutex_lock(&wt->global_lock);
printf("wt->current_clock_tic = %d\n", wt->current_clock_tic);
printf("wt->clock_tic_interval = %d\n", wt->clock_tic_interval);
printf("wt->wheel_size = %d\n", wt->wheel_size);
printf("wt->current_cycle_no = %d\n", wt->current_cycle_no);
printf("wt->wheel_thread = %p\n", &wt->wheel_thread);
printf("WT uptime = %s\n", hrs_min_sec_format(WT_UPTIME(wt)));
printf("wt->no_of_wt_elem = %u\n", wt->no_of_wt_elem);
printf("printing slots : \n");
for(; i < wt->wheel_size; i++){
slot_list_head = WT_SLOTLIST_HEAD(wt, i);
ITERATE_GLTHREAD_BEGIN(slot_list_head, curr){ << segfaulting here for i = 1
wt_elem = glthread_to_wt_elem(curr);
如果某个神圣的灵魂想在他的机器上试试。
请在这里下载代码:
https://github.com/sachinites/tcpip_stack
After downloading :
switch to branch "Hellos"
git checkout Hellos
Compile :
make all
run
./test.exe
to reproduce , run the cmd :
debug show node H1 timer
现在它的核心功能是:
print_wheel_timer()
实施于
轮定时器/轮定时器.c