https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=209521

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=219118

http://sources.redhat.com/ml/gdb-patches/2006-09/msg00092.html

Specific to Red Hat kernels, kernel.org kernels lockup on gdb "attach".

2007-03-20  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.base/attachstop.exp: Fix an incorrect adaptation on utrace

	regression of `kernel-xen-2.6.18-1.2767.el5.i686'.

2006-12-11  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb-6.5/gdb/linux-nat.c (linux_nat_attach): Handle already stopped

	processes, compiled either in a nonthreaded or a threaded mode.

2006-12-11  Jeff Johnston  <jjohnstn@redhat.com>

	    Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.base/attachstop.exp, gdb.base/attachstop.c: New files,

	test attaching to already stopped processes, compiled either in

	a nonthreaded or a threaded mode.

diff -u -ruNp gdb-6.5-orig/gdb/linux-nat.c gdb-6.5/gdb/linux-nat.c

--- gdb-6.5-orig/gdb/linux-nat.c	2006-12-12 00:30:18.000000000 +0100

+++ gdb-6.5/gdb/linux-nat.c	2006-12-11 23:42:23.000000000 +0100

@@ -567,7 +567,9 @@ linux_handle_extended_wait (int pid, int

 	  else if (ret != new_pid)

 	    internal_error (__FILE__, __LINE__,

 			    _("wait returned unexpected PID %d"), ret);

-	  else if (!WIFSTOPPED (status) || WSTOPSIG (status) != SIGSTOP)

+	  /* In some cases we get 0 for the `SIGSTOP' signal.  */

+	  else if (!WIFSTOPPED (status) ||

+		   (WSTOPSIG (status) != SIGSTOP && WSTOPSIG (status) != 0))

 	    internal_error (__FILE__, __LINE__,

 			    _("wait returned unexpected status 0x%x"), status);

 	}

@@ -1007,8 +1009,9 @@ lin_lwp_attach_lwp (ptid_t ptid, int ver

 	  lp->cloned = 1;

 	}

+      /* In some cases we get 0 for the `SIGSTOP' signal.  */

       gdb_assert (pid == GET_LWP (ptid)

-		  && WIFSTOPPED (status) && WSTOPSIG (status));

+		  && WIFSTOPPED (status));

       target_post_attach (pid);

@@ -1062,13 +1065,14 @@ linux_nat_attach (char *args, int from_t

       lp->cloned = 1;

     }

-  gdb_assert (pid == GET_PID (inferior_ptid)

-	      && WIFSTOPPED (status) && WSTOPSIG (status) == SIGSTOP);

+  /* In some cases we get 0 for the `SIGSTOP' signal.  */

+  gdb_assert (pid == GET_PID (inferior_ptid) && WIFSTOPPED (status)

+              && (WSTOPSIG (status) == SIGSTOP || WSTOPSIG (status) == 0));

   lp->stopped = 1;

-  /* Fake the SIGSTOP that core GDB expects.  */

-  lp->status = W_STOPCODE (SIGSTOP);

+  /* Provide the stop status that core GDB expects.  */

+  lp->status = status;

   lp->resumed = 1;

   if (debug_linux_nat)

     {

@@ -1509,7 +1513,8 @@ stop_wait_callback (struct lwp_info *lp,

 	  return stop_wait_callback (lp, flush_mask);

 	}

-      if (WSTOPSIG (status) != SIGSTOP)

+      /* In some cases we get 0 for the `SIGSTOP' signal.  */

+      if (WSTOPSIG (status) != SIGSTOP && WSTOPSIG (status) != 0)

 	{

 	  if (WSTOPSIG (status) == SIGTRAP)

 	    {

@@ -2093,8 +2098,10 @@ retry:

 	      if (options & __WCLONE)

 		lp->cloned = 1;

+	      /* In some cases we get 0 for the `SIGSTOP' signal.  */

 	      gdb_assert (WIFSTOPPED (status)

-			  && WSTOPSIG (status) == SIGSTOP);

+			  && (WSTOPSIG (status) == SIGSTOP

+			      || WSTOPSIG (status) == 0));

 	      lp->signalled = 1;

 	      if (!in_thread_list (inferior_ptid))

@@ -2195,8 +2202,10 @@ retry:

 	  /* Make sure we don't report a SIGSTOP that we sent

 	     ourselves in an attempt to stop an LWP, unless we

 	     intentionally want to see the SIGSTOP.  */

+	  /* In some cases we get 0 for the `SIGSTOP' signal.  */

 	  if (lp->signalled && !intentional_stop

-	      && WIFSTOPPED (status) && WSTOPSIG (status) == SIGSTOP)

+	      && WIFSTOPPED (status) && (WSTOPSIG (status) == SIGSTOP

+					 || WSTOPSIG (status) == 0))

 	    {

 	      if (debug_linux_nat)

 		fprintf_unfiltered (gdb_stdlog,

diff -u -ruNp gdb-6.5-orig/gdb/testsuite/gdb.base/attachstop.c gdb-6.5/gdb/testsuite/gdb.base/attachstop.c

--- gdb-6.5-orig/gdb/testsuite/gdb.base/attachstop.c	1970-01-01 01:00:00.000000000 +0100

+++ gdb-6.5/gdb/testsuite/gdb.base/attachstop.c	2006-12-11 23:58:22.000000000 +0100

@@ -0,0 +1,51 @@

+/* This testcase is part of GDB, the GNU debugger.

+

+   Copyright 2005 Free Software Foundation, Inc.

+

+   This program is free software; you can redistribute it and/or modify

+   it under the terms of the GNU General Public License as published by

+   the Free Software Foundation; either version 2 of the License, or

+   (at your option) any later version.

+

+   This program is distributed in the hope that it will be useful,

+   but WITHOUT ANY WARRANTY; without even the implied warranty of

+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

+   GNU General Public License for more details.

+ 

+   You should have received a copy of the GNU General Public License

+   along with this program; if not, write to the Free Software

+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */

+

+/* This program is intended to be started outside of gdb, then

+   manually stopped via a signal.  */

+

+#include <stddef.h>

+#include <unistd.h>

+#ifdef USE_THREADS

+#include <pthread.h>

+#endif

+

+static void *func (void *arg)

+{

+  sleep (10000);  /* Ridiculous time, but we will eventually kill it.  */

+  sleep (10000);  /* Second sleep.  */

+  return NULL;

+}

+

+int main ()

+{

+

+#ifndef USE_THREADS

+

+  func (NULL);

+

+#else

+

+  pthread_t th;

+  pthread_create (&th, NULL, func, NULL);

+  pthread_join (th, NULL);

+

+#endif

+

+  return 0;

+}

diff -u -ruNp gdb-6.5-orig/gdb/testsuite/gdb.base/attachstop.exp gdb-6.5/gdb/testsuite/gdb.base/attachstop.exp

--- gdb-6.5-orig/gdb/testsuite/gdb.base/attachstop.exp	1970-01-01 01:00:00.000000000 +0100

+++ gdb-6.5/gdb/testsuite/gdb.base/attachstop.exp	2006-12-12 00:26:39.000000000 +0100

@@ -0,0 +1,228 @@

+# Copyright 2005-2006

+

+# This program is free software; you can redistribute it and/or modify

+# it under the terms of the GNU General Public License as published by

+# the Free Software Foundation; either version 2 of the License, or

+# (at your option) any later version.

+# 

+# This program is distributed in the hope that it will be useful,

+# but WITHOUT ANY WARRANTY; without even the implied warranty of

+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

+# GNU General Public License for more details.

+# 

+# You should have received a copy of the GNU General Public License

+# along with this program; if not, write to the Free Software

+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

+

+# This test was created by modifying attach.exp.

+# This file was created by Jeff Johnston <jjohnstn@redhat.com>.

+# This file was updated by Jan Kratochvil <jan.kratochvil@redhat.com>.

+

+if $tracelevel then {

+    strace $tracelevel

+}

+

+set prms_id 0

+set bug_id 0

+

+# This test only works on Linux

+if { ![istarget "*-*-linux-gnu*"] } {

+    return 0

+}

+

+set testfile "attachstop"

+set srcfile  ${testfile}.c

+set binfile  ${objdir}/${subdir}/${testfile}

+set escapedbinfile  [string_to_regexp ${objdir}/${subdir}/${testfile}]

+

+#execute_anywhere "rm -f ${binfile}"

+remote_exec build "rm -f ${binfile}"

+# For debugging this test

+#

+#log_user 1

+

+proc corefunc { threadtype } {

+    global srcfile

+    global binfile

+    global escapedbinfile

+    global srcdir

+    global subdir

+    global gdb_prompt

+

+    if [get_compiler_info ${binfile}] {

+	return -1

+    }

+

+    # Start the program running and then wait for a bit, to be sure

+    # that it can be attached to.

+

+    set testpid [eval exec $binfile &]

+    exec sleep 2

+       

+    # Stop the program 

+    remote_exec build "kill -s STOP ${testpid}"

+

+    # Start with clean gdb

+    gdb_exit

+    gdb_start

+    gdb_reinitialize_dir $srcdir/$subdir

+    gdb_load ${binfile}

+

+    # Verify that we can attach to the process by first giving its

+    # executable name via the file command, and using attach with the

+    # process ID.

+

+    set test "$threadtype: set file, before attach1 to stopped process"

+    gdb_test_multiple "file $binfile" "$test" {

+       -re "Load new symbol table from.*y or n. $" {

+	    gdb_test "y" "Reading symbols from $escapedbinfile\.\.\.*done." \

+		    "$test (re-read)"

+	}

+	-re "Reading symbols from $escapedbinfile\.\.\.*done.*$gdb_prompt $" {

+	    pass "$test"

+	}

+    }

+

+    set test "$threadtype: attach1 to stopped, after setting file"

+    gdb_test_multiple "attach $testpid" "$test" {

+	-re "Attaching to program.*`?$escapedbinfile'?, process $testpid.*$gdb_prompt $" {

+	    pass "$test"

+	}

+    }

+

+    if {[string equal $threadtype threaded]} {

+	gdb_test "thread apply all bt" ".*sleep.*clone.*" "$threadtype: attach1 to stopped bt"

+    } else {

+	gdb_test "bt" ".*sleep.*main.*" "$threadtype: attach1 to stopped bt"

+    }

+

+    # Exit and detach the process.

+       

+    gdb_exit

+

+    set fileid [open /proc/${testpid}/status r];

+    gets $fileid line1;

+    gets $fileid line2;

+    close $fileid;

+

+    set test "$threadtype: attach1, exit leaves process stopped"

+    if {[string match "*(stopped)*" $line2]} {

+      pass $test

+    } else {

+      fail $test

+    }

+

+    # At this point, the process should still be stopped

+

+    gdb_start

+    gdb_reinitialize_dir $srcdir/$subdir

+    gdb_load ${binfile}

+

+    # Verify that we can attach to the process just by giving the

+    # process ID.

+       

+    set test "$threadtype: attach2 to stopped, after setting file"

+    gdb_test_multiple "attach $testpid" "$test" {

+	-re "Attaching to program.*`?$escapedbinfile'?, process $testpid.*$gdb_prompt $" {

+	    pass "$test"

+	}

+    }

+

+    if {[string equal $threadtype threaded]} {

+	gdb_test "thread apply all bt" ".*sleep.*clone.*" "$threadtype: attach2 to stopped bt"

+    } else {

+	gdb_test "bt" ".*sleep.*main.*" "$threadtype: attach2 to stopped bt"

+    }

+    gdb_breakpoint [gdb_get_line_number "$threadtype: Second sleep"]

+    set test "$threadtype: attach2 continue"

+    send_gdb "continue\n"

+    gdb_expect {

+      -re "Continuing"

+	{ pass "continue ($test)" }

+      timeout

+	{ fail "continue ($test) (timeout)" }

+    }

+

+    # For this to work we must be sure to consume the "Continuing."

+    # message first, or GDB's signal handler may not be in place.

+    after 1000 {send_gdb "\003"}

+    set test "$threadtype: attach2 stop unbreakable interrupt"

+    gdb_expect 4 {

+      -re "Program received signal SIGINT.*$gdb_prompt $"

+	{

+	  fail "$test (broke into)"

+	}

+      -re "Breakpoint \[0-9\].*$srcfile.*$gdb_prompt $"

+	{

+	  fail "$test (broke into)"

+	}

+      timeout

+	{

+	  pass $test

+	}

+    }

+

+    # Continue the program 

+    remote_exec build "kill -s CONT ${testpid}"

+

+    # Already sent before: after 1000 {send_gdb "\003"}

+    set test "$threadtype: attach2 stop by interrupt"

+    gdb_expect {

+      -re "Program received signal SIGSTOP,.*$gdb_prompt $"

+	{

+	  pass $test

+	}

+      -re "Breakpoint \[0-9\].*$srcfile.*$gdb_prompt $"

+	{

+	  pass $test

+	}

+      timeout

+	{

+	  fail "$test (timeout)"

+	}

+    }

+

+    gdb_exit

+

+    # Avoid some race:

+    exec sleep 2

+

+    # At this point, the process should be sleeping

+

+    set fileid2 [open /proc/${testpid}/status r];

+    gets $fileid2 line1;

+    gets $fileid2 line2;

+    close $fileid2;

+

+    set test "$threadtype: attach2, exit leaves process sleeping"

+    if {[string match "*(sleeping)*" $line2]} {

+      pass $test

+    } else {

+      fail $test

+    }

+

+    # Make sure we don't leave a process around to confuse

+    # the next test run (and prevent the compile by keeping

+    # the text file busy), in case the "set should_exit" didn't

+    # work.

+       

+    remote_exec build "kill -9 ${testpid}"

+}

+

+# build the test case first without threads

+#

+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {

+    gdb_suppress_entire_file "Testcase nonthraded compile failed, so all tests in this file will automatically fail."

+}

+

+corefunc nonthreaded

+

+# build the test case first without threads

+#

+if  { [gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug additional_flags=-DUSE_THREADS}] != "" } {

+    gdb_suppress_entire_file "Testcase threaded compile failed, so all tests in this file will automatically fail."

+}

+

+corefunc threaded

+

+return 0