[Bug gdb/23251] New: GDB ignores breakpoint when scheduler-locking is on

[vivi00791 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=23251

Bug ID: 23251
Summary: GDB ignores breakpoint when scheduler-locking is on
Product: gdb
Version: 8.1
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: gdb
Assignee: unassigned at sourceware dot org
Reporter: vivi00791 at gmail dot com
Target Milestone: ---

gdb will ignore the breakpoint on line 10 of program below
-------------------------------------------------------------
#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>

int i=2;
void sub(void)
{
if(i != 0){
i = 1/i;
}
}
int main(void)
{
pthread_t id, id2;
int ret, ret2;
ret=pthread_create(&id,NULL,(void *) sub,NULL);
ret2=pthread_create(&id2,NULL,(void *) sub,NULL);
if(ret!=0 & ret2!=0)
{
printf ("Create pthread error!\n");
exit (1);
}
pthread_join(id,NULL);
int re = 0;
pthread_join(id2,NULL);
return (0);
}
------------------------------------------------------------------
all gdb command and response list below:

(gdb) b 9
Breakpoint 1 at 0x804: file ./if.c, line 9.
(gdb) b 10
Breakpoint 2 at 0x80e: file ./if.c, line 10.
(gdb) r
Starting program: /home/aaaa/code/if
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff77f1700 (LWP 4035)]
[New Thread 0x7ffff6ff0700 (LWP 4036)]
[Switching to Thread 0x7ffff77f1700 (LWP 4035)]

Thread 2 "if" hit Breakpoint 1, sub () at ./if.c:9
9 if(i != 0){
(gdb) info th
Id Target Id Frame
1 Thread 0x7ffff7fda700 (LWP 4031) "if" 0x00007ffff7bc19dd in pthread_join
(
threadid=140737345689344, thread_return=0x0) at pthread_join.c:90
* 2 Thread 0x7ffff77f1700 (LWP 4035) "if" sub () at ./if.c:9
3 Thread 0x7ffff6ff0700 (LWP 4036) "if" clone ()
at ../sysdeps/unix/sysv/linux/x86_64/clone.S:80
(gdb) thread 3
[Switching to thread 3 (Thread 0x7ffff6ff0700 (LWP 4036))]
#0 clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:80
80 ../sysdeps/unix/sysv/linux/x86_64/clone.S: No such file or directory.
(gdb) set scheduler-locking on
(gdb) r
The program being debugged has been started already.
Start it from the beginning? (y or n) n
Program not restarted.
(gdb) c
Continuing.

Thread 3 "if" hit Breakpoint 1, sub () at ./if.c:9
9 if(i != 0){
(gdb) info th
Id Target Id Frame
1 Thread 0x7ffff7fda700 (LWP 4031) "if" 0x00007ffff7bc19dd in pthread_join
(
threadid=140737345689344, thread_return=0x0) at pthread_join.c:90
2 Thread 0x7ffff77f1700 (LWP 4035) "if" sub () at ./if.c:9
* 3 Thread 0x7ffff6ff0700 (LWP 4036) "if" sub () at ./if.c:9
(gdb) thread 2
[Switching to thread 2 (Thread 0x7ffff77f1700 (LWP 4035))]
#0 sub () at ./if.c:9
9 if(i != 0){
(gdb) c
Continuing.

Thread 2 "if" hit Breakpoint 2, sub () at ./if.c:10
10 i = 1/i;
(gdb) thread 2
[Switching to thread 2 (Thread 0x7ffff77f1700 (LWP 4035))]
#0 sub () at ./if.c:10
10 i = 1/i;
(gdb) c
Continuing.
[Thread 0x7ffff77f1700 (LWP 4035) exited]
No unwaited-for children left.
(gdb) thread 3
[Switching to thread 3 (Thread 0x7ffff6ff0700 (LWP 4036))]
#0 sub () at ./if.c:9
9 if(i != 0){
(gdb) c
Continuing.
[Thread 0x7ffff6ff0700 (LWP 4036) exited]
No unwaited-for children left.
(gdb) info b
Num Type Disp Enb Address What
1 breakpoint keep y 0x0000555555554804 in sub at ./if.c:9
breakpoint already hit 2 times
2 breakpoint keep y 0x000055555555480e in sub at ./if.c:10
breakpoint already hit 1 time
(gdb)

[vivi00791 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=23251

Sherl Chen <vivi00791 at gmail dot com> changed:

What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |critical