998d452ac8
Running gdb.threads/fork-plus-threads.exp against gdbserver in extended-remote mode, even though the test passes, we still see broken behavior: (gdb) PASS: gdb.threads/fork-plus-threads.exp: set detach-on-fork off continue & Continuing. (gdb) PASS: gdb.threads/fork-plus-threads.exp: continue & [New Thread 28092.28092] [Thread 28092.28092] #2 stopped. [New Thread 28094.28094] [Inferior 2 (process 28092) exited normally] [New Thread 28094.28105] [New Thread 28094.28109] ... [Thread 28174.28174] #18 stopped. [New Thread 28185.28185] [Inferior 10 (process 28174) exited normally] [New Thread 28185.28196] [Thread 28185.28185] #20 stopped. Cannot remove breakpoints because program is no longer writable. Further execution is probably impossible. [Inferior 11 (process 28185) exited normally] [Inferior 1 (process 28091) exited normally] PASS: gdb.threads/fork-plus-threads.exp: reached breakpoint info threads No threads. (gdb) PASS: gdb.threads/fork-plus-threads.exp: no threads left info inferiors Num Description Executable * 1 <null> /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.threads/fork-plus-threads (gdb) PASS: gdb.threads/fork-plus-threads.exp: only inferior 1 left All the "[Thread FOO] #NN stopped." above are bogus, as well as the "Cannot remove breakpoints because program is no longer writable.", which is a consequence. The problem is that when we intercept a fork event, we should report the event for the parent, only, and leave the child stopped, but not report its stop event. GDB later decides whether to follow the parent or the child. But because handle_extended_wait does not set the child's last_status.kind to TARGET_WAITKIND_STOPPED, a stop_all_threads/unstop_all_lwps sequence (e.g., from trying to access memory) by mistake ends up queueing a SIGSTOP on the child, resuming it, and then when that SIGSTOP is intercepted, because the LWP has last_resume_kind set to resume_stop, gdbserver reports the stop to GDB, as GDB_SIGNAL_0: ... >>>> entering unstop_all_lwps unstopping all lwps proceed_one_lwp: lwp 1600 client wants LWP to remain 1600 stopped proceed_one_lwp: lwp 1828 Client wants LWP 1828 to stop. Making sure it has a SIGSTOP pending ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Sending sigstop to lwp 1828 pc is 0x3615ebc7cc Resuming lwp 1828 (continue, signal 0, stop expected) continue from pc 0x3615ebc7cc unstop_all_lwps done sigchld_handler <<<< exiting unstop_all_lwps handling possible target event >>>> entering linux_wait_1 linux_wait_1: [<all threads>] my_waitpid (-1, 0x40000001) my_waitpid (-1, 0x1): status(137f), 1828 LWFE: waitpid(-1, ...) returned 1828, ERRNO-OK LLW: waitpid 1828 received Stopped (signal) (stopped) pc is 0x3615ebc7cc Expected stop. LLW: resume_stop SIGSTOP caught for LWP 1828.1828. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ... linux_wait_1 ret = LWP 1828.1828, 1, 0 <<<< exiting linux_wait_1 Writing resume reply for LWP 1828.1828:1 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Tested on x86_64 Fedora 20, extended-remote. gdb/gdbserver/ChangeLog: 2015-07-30 Pedro Alves <palves@redhat.com> * linux-low.c (handle_extended_wait): Set the child's last reported status to TARGET_WAITKIND_STOPPED. |
||
|---|---|---|
| bfd | ||
| binutils | ||
| config | ||
| cpu | ||
| elfcpp | ||
| etc | ||
| gas | ||
| gdb | ||
| gold | ||
| gprof | ||
| include | ||
| intl | ||
| ld | ||
| libdecnumber | ||
| libiberty | ||
| opcodes | ||
| readline | ||
| sim | ||
| texinfo | ||
| zlib | ||
| .cvsignore | ||
| .gitattributes | ||
| .gitignore | ||
| COPYING | ||
| COPYING.LIB | ||
| COPYING.LIBGLOSS | ||
| COPYING.NEWLIB | ||
| COPYING3 | ||
| COPYING3.LIB | ||
| ChangeLog | ||
| MAINTAINERS | ||
| Makefile.def | ||
| Makefile.in | ||
| Makefile.tpl | ||
| README | ||
| README-maintainer-mode | ||
| compile | ||
| config-ml.in | ||
| config.guess | ||
| config.rpath | ||
| config.sub | ||
| configure | ||
| configure.ac | ||
| depcomp | ||
| djunpack.bat | ||
| install-sh | ||
| libtool.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
| ltversion.m4 | ||
| lt~obsolete.m4 | ||
| makefile.vms | ||
| missing | ||
| mkdep | ||
| mkinstalldirs | ||
| move-if-change | ||
| setup.com | ||
| src-release.sh | ||
| symlink-tree | ||
| ylwrap | ||
README
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.