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Pedro Alves ced2dffbf1 Fix failure to detach if process exits while detaching on Linux
This commit fixes detaching on Linux when some thread exits the whole
thread group (process) just while we're detaching.

On Linux, a ptracer must detach from each LWP individually, with
PTRACE_DETACH.  Since PTRACE_DETACH sets the thread running free, if
one of the already-detached threads causes the whole thread group to
exit (e.g., simply calls exit), the kernel force-kills the other
threads in the group, making them zombie, just as we're still
detaching them.  Since PTRACE_DETACH against a zombie thread fails
with ESRCH, and gdb/gdbserver are not expecting this, the detach fails
with an error like: "Can't detach process: No such process.".

This patch detects this detach failure as normal, and instead of
erroring out, reaps the now-dead thread.

New test included, that exercises several different scenarios that
cause GDB/GDBserver to error out when it should not.

Tested on x86-64 GNU/Linux with {unix, native-gdbserver,
native-extended-gdbserver}

Note: without the previous fix, the "single-process + continue"
variant of the new test would fail with:

 (gdb) PASS: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: switch to parent
 continue
 Continuing.
 Warning:
 Could not insert hardware watchpoint 3.
 Could not insert hardware breakpoints:
 You may have requested too many hardware breakpoints/watchpoints.

 Command aborted.
 (gdb) FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue

gdb/gdbserver/ChangeLog:
2016-07-01  Pedro Alves  <palves@redhat.com>
	    Antoine Tremblay  <antoine.tremblay@ericsson.com>

	* linux-low.c: Change interface to take the target lwp_info
	pointer directly and return void.  Handle detaching from a zombie
	thread.
	(linux_detach_lwp_callback): New function.
	(linux_detach): Detach from the leader thread after detaching from
	the clone threads.

gdb/ChangeLog:
2016-07-01  Pedro Alves  <palves@redhat.com>
	    Antoine Tremblay  <antoine.tremblay@ericsson.com>

	* inf-ptrace.c (inf_ptrace_detach_success): New function, factored
	out from ...
	(inf_ptrace_detach): ... here.
	* inf-ptrace.h (inf_ptrace_detach_success): New declaration.
	* linux-nat.c (get_pending_status): Rename to ...
	(get_detach_signal): ... this, and return a host signal instead of
	filling in a wait status.
	(detach_one_lwp): New function, factored out from detach_callback
	and adjusted to handle detaching from a zombie thread.
	(detach_callback): Skip the leader thread.
	(linux_nat_detach): No longer defer to inf_ptrace_detach to detach
	the leader thread, nor build a signal string to pass down.
	Instead, use target_announce_detach, detach_one_lwp and
	inf_ptrace_detach_success.

gdb/testsuite/ChangeLog:
2016-07-01  Pedro Alves  <palves@redhat.com>
	    Antoine Tremblay  <antoine.tremblay@ericsson.com>

	* gdb.threads/process-dies-while-detaching.c: New file.
	* gdb.threads/process-dies-while-detaching.exp: New file.
2016-07-01 11:27:06 +01:00
bfd Automatic date update in version.in 2016-07-01 00:00:22 +00:00
binutils Expect the objcopy without global symbols test to fail for ARM and AArch64 targets. 2016-07-01 10:34:08 +01:00
config
cpu
elfcpp Add support for MIPS .rld_map section. 2016-06-20 12:16:26 -07:00
etc Fix compile time warning messages building with gcc v6.1.1 2016-06-13 10:49:26 +01:00
gas x86-64/MPX: relax no-RIP-relative-addressing testcase 2016-07-01 11:17:30 +02:00
gdb Fix failure to detach if process exits while detaching on Linux 2016-07-01 11:27:06 +01:00
gold Fix gold testsuite failure with GCC 6. 2016-06-29 23:24:35 -07:00
gprof
include [ARM][GAS] ARMv8.2 should enable ARMv8.1 NEON instructions. 2016-06-30 10:46:51 +01:00
intl
ld Add marker for 2.27 branch. 2016-07-01 10:58:29 +02:00
libdecnumber
libiberty
opcodes x86: allow suffix-less movzw and 64-bit movzb 2016-07-01 09:01:41 +02:00
readline
sim Add support for simulating big-endian AArch64 binaries. 2016-06-30 09:10:41 +01:00
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ChangeLog [TILEPro] Don't build gdb 2016-06-28 14:16:15 -04:00
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configure.ac [TILEPro] Don't build gdb 2016-06-28 14:16:15 -04:00
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		   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,
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If you have more than one compiler on your system, it is often best to
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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.