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8a06aea71e
On GNU/Linux, if the running kernel supports clone events, then
linux-thread-db.c defers thread listing to the target beneath:
static void
thread_db_update_thread_list (struct target_ops *ops)
{
...
if (target_has_execution && !thread_db_use_events ())
ops->beneath->to_update_thread_list (ops->beneath);
else
thread_db_update_thread_list_td_ta_thr_iter (ops);
...
}
However, when live debugging, the target beneath, linux-nat.c, does
not implement the to_update_thread_list method. The result is that if
a thread is marked exited (because it can't be deleted right now,
e.g., it was the selected thread), then it won't ever be deleted,
until the process exits or is killed/detached.
A similar thing happens with the remote.c target. Because its
target_update_thread_list implementation skips exited threads when it
walks the current thread list looking for threads that no longer exits
on the target side, using ALL_NON_EXITED_THREADS_SAFE, stale exited
threads are never deleted.
This is not a big deal -- I can't think of any way this might be user
visible, other than gdb's memory growing a tiny bit whenever a thread
gets stuck in exited state. Still, might as well clean things up
properly.
All other targets use prune_threads, so are unaffected.
The fix adds a ALL_THREADS_SAFE macro, that like
ALL_NON_EXITED_THREADS_SAFE, walks the thread list and allows deleting
the iterated thread, and uses that in places that are walking the
thread list in order to delete threads. Actually, after converting
linux-nat.c and remote.c to use this, we find the only other user of
ALL_NON_EXITED_THREADS_SAFE is also walking the list to delete
threads. So we convert that too, and end up deleting
ALL_NON_EXITED_THREADS_SAFE.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/ChangeLog
2015-04-07 Pedro Alves <palves@redhat.com>
* gdbthread.h (ALL_NON_EXITED_THREADS_SAFE): Rename to ...
(ALL_THREADS_SAFE): ... this, and don't skip exited threads.
(delete_exited_threads): New declaration.
* infrun.c (follow_exec): Use ALL_THREADS_SAFE.
* linux-nat.c (linux_nat_update_thread_list): New function.
(linux_nat_add_target): Install it.
* remote.c (remote_update_thread_list): Use ALL_THREADS_SAFE.
* thread.c (prune_threads): Use ALL_THREADS_SAFE.
(delete_exited_threads): New function.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.