[Bug gdb/10236] asyncronous execution becomes unusable if you single step to the end of an executable

["pedro at codesourcery dot com" <sourceware-bugzilla at sourceware dot org>]

------- Additional Comments From pedro at codesourcery dot com  2009-06-03 22:55 -------
Subject: Re:  New: asyncronous execution becomes unusable if you single step to the end of an executable

Thanks.  I can reproduce this in current mainline.  longjmp
breakpoints are being left behind:

(gdb) set target-async 1
(gdb) r&
Starting program: /home/pedro/gdb/sspaces/build/gdb/a.out
(gdb)
Breakpoint 1, main () at bug.c:1
1       int main(int,char**){return 0;}
Current language:  auto; currently c++
maint info breakpoints
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   0x0000000000400543 in main at bug.c:1
        breakpoint already hit 1 time
-1      shlib events   keep y   0x00007ffff7dee990 <_dl_debug_state>
        breakpoint already hit 2 times
(gdb) n
0x00007ffff73021c4 in __libc_start_main () from /lib/libc.so.6
(gdb)
Single stepping until exit from function __libc_start_main,
which has no line number information.

Program exited normally.
(gdb) maint info breakpoints
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   0x0000000000400543 in main at bug.c:1
        breakpoint already hit 1 time
-1      shlib events   keep y   0x00007ffff7dee990 <_dl_debug_state>
        breakpoint already hit 2 times
0       longjmp        keep y   0x00007ffff7315eb0 <siglongjmp> thread 1
        stop only in thread 1
0       longjmp        keep y   0x00007ffff7315eb0 <siglongjmp> thread 1
        stop only in thread 1
0       longjmp        keep y   0x00007ffff7315eb0 <siglongjmp> thread 1
        stop only in thread 1
0       step resume    dstp y   0x00007ffff73021cb <__libc_start_main+251> thread 1
        stop only in thread 1
(gdb) r
Starting program: /home/pedro/gdb/sspaces/build/gdb/a.out
Warning:
Cannot insert breakpoint 0.
Error accessing memory address 0x7ffff7315eb0: Input/output error.

(gdb) 

Sounds like something is wrong with cleaning up after threads that
had continuations on them (step_1_continuation is responsible for
clearing longjmp breakpoints).  I do wonder if replacing opaque
continuations with state flags wouldn't be better...


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http://sourceware.org/bugzilla/show_bug.cgi?id=10236

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