Re: [patch] s390*: watchpoints regression [repost]

[Pedro Alves <pedro@codesourcery.com>]

On Saturday 17 December 2011 19:56:32, Pedro Alves wrote:
> On Saturday 17 December 2011 19:44:54, Jan Kratochvil wrote:
> > On Sat, 17 Dec 2011 20:40:13 +0100, Pedro Alves wrote:
> > > In the loop that runs through the shell, fork-child.c:startup_inferior,
> > > nothing inserts breakpoints/watchpoints.  So nothing ends up
> > > setting lwp->arch_private->debug_registers_changed, and so we should
> > > not be setting DR_CONTROL to 0 for the wrapper shell.  Do you
> > > actually see it happen?
> > 
> > I see it happenning.  [attached]
> 
> Ah, I forgot this:
> 
> static void
> i386_linux_new_thread (struct lwp_info *lp)
> {
>   struct arch_lwp_info *info = XCNEW (struct arch_lwp_info);
> 
>   info->debug_registers_changed = 1;
> 
>   lp->arch_private = info;
> }
> 
> Hmm.  I'm starting to think that the easiest is jut to
> go back at not calling new_thread for the first thread.
> Let me give that a try.

Seems to work fine.  This should obsolete the s390 patch.

I think GDBserver has a similar problem with --wrapper.

-- 
Pedro Alves

2011-12-17  Pedro Alves  <pedro@codesourcery.com>
            Jan Kratochvil  <jan.kratochvil@redhat.com>

        * linux-nat.c (add_lwp): Don't call linux_nat_new_thread on the
	first LWP.
	* amd64-linux-nat.c (update_debug_registers_callback): Instantiate
	`lwp->arch_private' if NULL.
	(amd64_linux_prepare_to_resume): Do nothing if `lwp->arch_private'
	is NULL.
	* i386-linux-nat.c (update_debug_registers_callback): Instantiate
	`lwp->arch_private' if NULL.
	(i386_linux_prepare_to_resume): Do nothing if `lwp->arch_private'
	is NULL.
---

 gdb/amd64-linux-nat.c |    8 ++++++++
 gdb/i386-linux-nat.c  |    8 ++++++++
 gdb/linux-nat.c       |    2 +-
 3 files changed, 17 insertions(+), 1 deletions(-)

diff --git a/gdb/amd64-linux-nat.c b/gdb/amd64-linux-nat.c
index 288160b..6ee9596 100644
--- a/gdb/amd64-linux-nat.c
+++ b/gdb/amd64-linux-nat.c
@@ -343,6 +343,9 @@ amd64_linux_dr_get_status (void)
 static int
 update_debug_registers_callback (struct lwp_info *lwp, void *arg)
 {
+  if (lwp->arch_private == NULL)
+    lwp->arch_private = XCNEW (struct arch_lwp_info);
+
   /* The actual update is done later just before resuming the lwp, we
      just mark that the registers need updating.  */
   lwp->arch_private->debug_registers_changed = 1;
@@ -386,6 +389,11 @@ amd64_linux_prepare_to_resume (struct lwp_info *lwp)
 {
   int clear_status = 0;
 
+  /* This is the main thread still going through the shell, or, no
+     watchpoint has been set yet.  */
+  if (lwp->arch_private == NULL)
+    return;
+
   if (lwp->arch_private->debug_registers_changed)
     {
       struct i386_debug_reg_state *state = i386_debug_reg_state ();
diff --git a/gdb/i386-linux-nat.c b/gdb/i386-linux-nat.c
index 190979b..3c56a22 100644
--- a/gdb/i386-linux-nat.c
+++ b/gdb/i386-linux-nat.c
@@ -715,6 +715,9 @@ i386_linux_dr_get_status (void)
 static int
 update_debug_registers_callback (struct lwp_info *lwp, void *arg)
 {
+  if (lwp->arch_private == NULL)
+    lwp->arch_private = XCNEW (struct arch_lwp_info);
+
   /* The actual update is done later just before resuming the lwp, we
      just mark that the registers need updating.  */
   lwp->arch_private->debug_registers_changed = 1;
@@ -758,6 +761,11 @@ i386_linux_prepare_to_resume (struct lwp_info *lwp)
 {
   int clear_status = 0;
 
+  /* This is the main thread still going through the shell, or, no
+     watchpoint has been set yet.  */
+  if (lwp->arch_private == NULL)
+    return;
+
   if (lwp->arch_private->debug_registers_changed)
     {
       struct i386_debug_reg_state *state = i386_debug_reg_state ();
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index 1cbfc44..2b1ecb7 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -1151,7 +1151,7 @@ add_lwp (ptid_t ptid)
   lp->next = lwp_list;
   lwp_list = lp;
 
-  if (linux_nat_new_thread != NULL)
+  if (num_lwps (GET_PID (ptid)) > 1 && linux_nat_new_thread != NULL)
     linux_nat_new_thread (lp);
 
   return lp;