On Mon, 2006-12-18 at 20:05 +0100, Nicholas Mc Guire wrote:
>
> Hi !
>
> I have a phenomena that I don't quite understand. gdbserver forks and
> after setting ptrace (PTRACE_TRACEME, 0, 0, 0); it then execv
> (program, allargs); when this child process hits ptrace_stoped (breakpoint
> it does the following in kernel space:
>
> pid 1242 = child process
> pid 1241 = gdbserver
> pid 0 = kernel
> pid -1 = interrupt
> pid
> 1 559 5 1242 ptrace_stop
> 3 6 2 1242 | do_notify_parent_cldstop
> 4 3 2 1242 | | __group_send_sig_info
> 5 1 1 1242 | | | handle_stop_signal
> 7 0 0 1242 | | | sig_ignored
> 8 1 0 1242 | | __wake_up_sync
> 8 1 1 1242 | | | __wake_up_common
> 10 547 541 1242 | schedule
> 10 2 2 1242 | | profile_hit
> 13 1 1 1242 | | sched_clock
> 15 1 0 1242 | | deactivate_task
> 15 1 1 1242 | | | dequeue_task
> 19 2 2 0 | | __switch_to
> ----------- !!!! start --------------
> 24 574 574 0 default_idle
> ----------- $$$$ end ----------------
> ----------- //// start --------------
> 780 41 12 0 do_IRQ
> 780 29 2 -1 / __do_IRQ
> ...
> 807 2 2 -1 / / / enable_8259A_irq
> ----------- //// end ----------------
> ----------- {{{{ start --------------
> 810 11 0 0 do_softirq
> ...
> 820 0 0 -1 { { { preempt_schedule
> ----------- {{{{ end ----------------
> ----------- %%%% start --------------
> 822 358 1 0 preempt_schedule_irq
> ...
> 827 1 1 1241 % % __switch_to
> ----------- %%%% end ----------------
> 829 1 1 1241 ( ( ( del_timer
> ----------- (((( end ----------------
> ----------- ]]]] start --------------
> 837 8 2 1241 sys_waitpid
>
> So basically child signals -> delayed to next tick -> parent wakes up.
Hm. What does the trace of gdbserver look like prior to the clild doing
do_notify_parent_cldstop()? Sleeping someplace other than wait4?
-Mike
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