src/gdb ChangeLog linux-nat.c gdbserver/Change ...

[palves at sourceware dot org]

CVSROOT:	/cvs/src
Module name:	src
Changes by:	palves@sourceware.org	2013-03-22 14:52:26

Modified files:
	gdb            : ChangeLog linux-nat.c 
	gdb/gdbserver  : ChangeLog linux-low.c 

Log message:
	Linux: No need to set ptrace event options in fork/clone children.
	
	Oleg Nesterov told me that the Linux kernel copies the parent's ptrace
	options to fork/clone children, so there's no need for GDB to do that
	manually.
	
	I was actually a bit surprised, since I thought the ptracer had to
	always set the ptrace options itself, and GDB is indeed calling
	PTRACE_SETOPTIONS for each new fork child, if it'll stay attached.
	
	Looking at the history of that code, I found that is was actually I
	who added that set-ptrace-options-in-children bit, back in
	http://sourceware.org/ml/gdb-patches/2009-05/msg00656.html.  But,
	honestly, I don't recall why I needed that.  I think I may have just
	blindly believed it was necessary.
	
	I then looked back at the history of all the PTRACE_SETOPTIONS code we
	have, and found that gdb never did copy the ptrace options before my
	patch.  But, when gdbserver learnt to use PTRACE_EVENT_CLONE, at
	http://sourceware.org/ml/gdb-patches/2007-10/msg00547.html, it was
	made to do 'ptrace (PTRACE_SETOPTIONS, new_pid, 0,
	PTRACE_O_TRACECLONE)' for all new clones.  Hmmm.  But, GDB itself
	never did that, so it can't really ever have been necessary, I
	believe, otherwise GDB should have been doing it too.
	
	(GDBserver doesn't support following forks, and so naturally doesn't
	do any PTRACE_SETOPTIONS on fork children.)
	
	So this patch removes the -I believe- unnecessary ptrace syscalls.
	
	Tested on x86_64 Fedora 17, native/gdbserver, and on x86_64 RHEL5
	native/gdbserver (Linux 2.6.18, I think a ptrace-on-utrace kernel).
	No regressions.
	
	gdb/
	2013-03-22  Pedro Alves  <palves@redhat.com>
	
	* linux-nat.c (linux_child_follow_fork): Don't call
	linux_enable_event_reporting.
	(linux_handle_extended_wait): Don't call
	linux_enable_event_reporting.
	
	gdb/gdbserver/
	2013-03-22  Pedro Alves  <palves@redhat.com>
	
	* linux-low.c (handle_extended_wait): Don't call
	linux_enable_event_reporting.

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/ChangeLog.diff?cvsroot=src&r1=1.15300&r2=1.15301
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/linux-nat.c.diff?cvsroot=src&r1=1.265&r2=1.266
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/gdbserver/ChangeLog.diff?cvsroot=src&r1=1.701&r2=1.702
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/gdbserver/linux-low.c.diff?cvsroot=src&r1=1.234&r2=1.235