[PATCH] Remove support for thread events without PTRACE_EVENT_CLONE in GDB.
Antoine Tremblay
antoine.tremblay@ericsson.com
Thu Dec 10 15:21:00 GMT 2015
On 12/10/2015 09:47 AM, Pedro Alves wrote:
> On 12/09/2015 05:39 PM, Antoine Tremblay wrote:
>> Before, on systems that did not support PTRACE_EVENT_CLONE, both GDB and
>> GDBServer coordinated with libthread_db.so to insert breakpoints at magic
>> locations in libpthread.so, in order to break at thread creation and
>> thread death.
>>
>> Support for thread events was removed from GDBServer as patch:
>> https://sourceware.org/ml/gdb-patches/2015-11/msg00466.html
>>
>> This patch removes support for thread events in GDB.
>>
>> No regressions found on Ubuntu 14.04 x86_64.
>>
>> gdb/ChangeLog:
>> * breakpoint.c (create_thread_event_breakpoint): Remove.
>> (remove_thread_event_breakpoints): Remove.
>
> That's still used:
>
> $ grep create_thread_event_breakpoint gdb/*
> gdb/aix-thread.c: if (!create_thread_event_breakpoint (target_gdbarch (), pd_brk_addr))
>
>
Ouch, I had missed that one. I'll re-add the function.
Also I noticed I forgot to remove the declaration in breakpoint.h I'll
fix that for remove_thread_event_breakpoint.
>
>> - /* Under GNU/Linux, we have to attach to each and every thread. */
>> - if (target_has_execution
>> - && tp == NULL)
>> - {
>> - int res;
>> -
>> - res = lin_lwp_attach_lwp (ptid_build (ptid_get_pid (ptid),
>> - ti_p->ti_lid, 0));
>> - if (res < 0)
>> - {
>> - /* Error, stop iterating. */
>
>
> Is lin_lwp_attach_lwp used anywhere after this?
>
No indeed, Removing.
>
>
>> @@ -1592,24 +1200,10 @@ find_new_threads_callback (const td_thrhandle_t *th_p, void *data)
>>
>> if (ti.ti_tid == 0)
>> {
>> - /* A thread ID of zero means that this is the main thread, but
>> - glibc has not yet initialized thread-local storage and the
>> - pthread library. We do not know what the thread's TID will
>> - be yet. Just enable event reporting and otherwise ignore
>> - it. */
>
> You shouldn't remove the whole comment -- it's still all correct
> except the last sentence.
>
Yes I hesitated on that one, it felt like the reason for the comment was
the last sentence so I removed it.
But I'm OK with leaving it there.
V2 follows in next mail.
Thanks,
Antoine
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