Linux/ptrace: don't convert ptids when asking inf-ptrace layer to resume LWP
Commit Message
On 03/03/2015 04:25 PM, Pedro Alves wrote:
> On 03/03/2015 04:04 PM, Mark Kettenis wrote:
>> I see that this assumption has made its way into infrun.c:
>>
>> inferior_ptid = ptid_build (child_pid, child_pid, 0);
>>
>> That's wrong. The OS-specific code should fill in the LWPID part with
>> the appropriate value by using thread_change_ptid(). AFAICT, the
>> linux-nat.c code does that properly.
>
> I think you're pointing at the follow fork code. That was born out
> of a generalization of code that used to live in linux-nat.c, inf-ptrace.c,
> etc. (d83ad864). The old inf-ptrace.c code used to do:
>
> /* Switch inferior_ptid out of the parent's way. */
> inferior_ptid = pid_to_ptid (fpid);
>
> /* Delete the parent. */
> detach_inferior (pid);
>
> add_thread_silent (inferior_ptid);
>
>
> 'child_pid' is set at the top of follow_fork_inferior, like:
>
> child_pid
> = ptid_get_pid (inferior_thread ()->pending_follow.value.related_pid);
>
> I think I even remember that long ago "related_pid" used to be
> a single int, not a ptid.
>
> This is again another case of losing information. I think we could
> easily make that:
>
> child_pid = inferior_thread ()->pending_follow.value.related_pid;
>
> and drop that ptid_build, and things should work everywhere.
>
> I have no idea if "follow fork" actually works on BSD targets correctly.
> A buildbot slave would catch breakages like these. ( hint :-) )
Like this. Let me know what you think.
----
From c557c13f6bfe0126dd9ab74576951b127fd39531 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Tue, 3 Mar 2015 16:36:28 +0000
Subject: [PATCH] follow-fork: don't lose the ptids as set by the target
This Linuxism has made its way into infrun.c, in the follow-fork code:
inferior_ptid = ptid_build (child_pid, child_pid, 0);
The OS-specific code should fill in the LWPID, TID parts with the
appropriate values, if any, and the core code should not be peeking at
the components of the ptids.
gdb/
2015-03-03 Pedro Alves <palves@redhat.com>
* infrun.c (follow_fork_inferior): Use the whole of the
inferior_ptid and pending_follow.related_pid ptids instead of
building ptids from the process components. Adjust verbose output
to use target_pid_to_str.
* linux-nat.c (linux_child_follow_fork): Use the whole of the
inferior_ptid and pending_follow.related_pid ptids instead of
building ptids from the process components.
---
gdb/infrun.c | 33 ++++++++++++++-------------------
gdb/linux-nat.c | 15 +++++++--------
2 files changed, 21 insertions(+), 27 deletions(-)
@@ -408,15 +408,12 @@ static int
follow_fork_inferior (int follow_child, int detach_fork)
{
int has_vforked;
- int parent_pid, child_pid;
+ ptid_t parent_ptid, child_ptid;
has_vforked = (inferior_thread ()->pending_follow.kind
== TARGET_WAITKIND_VFORKED);
- parent_pid = ptid_get_lwp (inferior_ptid);
- if (parent_pid == 0)
- parent_pid = ptid_get_pid (inferior_ptid);
- child_pid
- = ptid_get_pid (inferior_thread ()->pending_follow.value.related_pid);
+ parent_ptid = inferior_ptid;
+ child_ptid = inferior_thread ()->pending_follow.value.related_pid;
if (has_vforked
&& !non_stop /* Non-stop always resumes both branches. */
@@ -460,10 +457,9 @@ holding the child stopped. Try \"set detach-on-fork\" or \
{
target_terminal_ours_for_output ();
fprintf_filtered (gdb_stdlog,
- _("Detaching after %s from "
- "child process %d.\n"),
+ _("Detaching after %s from child %s.\n"),
has_vforked ? "vfork" : "fork",
- child_pid);
+ target_pid_to_str (child_ptid));
}
}
else
@@ -472,7 +468,7 @@ holding the child stopped. Try \"set detach-on-fork\" or \
struct cleanup *old_chain;
/* Add process to GDB's tables. */
- child_inf = add_inferior (child_pid);
+ child_inf = add_inferior (ptid_get_pid (child_ptid));
parent_inf = current_inferior ();
child_inf->attach_flag = parent_inf->attach_flag;
@@ -483,7 +479,7 @@ holding the child stopped. Try \"set detach-on-fork\" or \
old_chain = save_inferior_ptid ();
save_current_program_space ();
- inferior_ptid = ptid_build (child_pid, child_pid, 0);
+ inferior_ptid = child_ptid;
add_thread (inferior_ptid);
child_inf->symfile_flags = SYMFILE_NO_READ;
@@ -549,17 +545,16 @@ holding the child stopped. Try \"set detach-on-fork\" or \
{
target_terminal_ours_for_output ();
fprintf_filtered (gdb_stdlog,
- _("Attaching after process %d "
- "%s to child process %d.\n"),
- parent_pid,
+ _("Attaching after %s %s to child %s.\n"),
+ target_pid_to_str (parent_ptid),
has_vforked ? "vfork" : "fork",
- child_pid);
+ target_pid_to_str (child_ptid));
}
/* Add the new inferior first, so that the target_detach below
doesn't unpush the target. */
- child_inf = add_inferior (child_pid);
+ child_inf = add_inferior (ptid_get_pid (child_ptid));
parent_inf = current_inferior ();
child_inf->attach_flag = parent_inf->attach_flag;
@@ -596,8 +591,8 @@ holding the child stopped. Try \"set detach-on-fork\" or \
target_terminal_ours_for_output ();
fprintf_filtered (gdb_stdlog,
_("Detaching after fork from "
- "child process %d.\n"),
- child_pid);
+ "child %s.\n"),
+ target_pid_to_str (child_ptid));
}
target_detach (NULL, 0);
@@ -609,7 +604,7 @@ holding the child stopped. Try \"set detach-on-fork\" or \
this new thread, before cloning the program space, and
informing the solib layer about this new process. */
- inferior_ptid = ptid_build (child_pid, child_pid, 0);
+ inferior_ptid = child_ptid;
add_thread (inferior_ptid);
/* If this is a vfork child, then the address-space is shared
@@ -387,20 +387,19 @@ linux_child_follow_fork (struct target_ops *ops, int follow_child,
int status = W_STOPCODE (0);
struct cleanup *old_chain;
int has_vforked;
+ ptid_t parent_ptid, child_ptid;
int parent_pid, child_pid;
has_vforked = (inferior_thread ()->pending_follow.kind
== TARGET_WAITKIND_VFORKED);
- parent_pid = ptid_get_lwp (inferior_ptid);
- if (parent_pid == 0)
- parent_pid = ptid_get_pid (inferior_ptid);
- child_pid
- = ptid_get_pid (inferior_thread ()->pending_follow.value.related_pid);
-
+ parent_ptid = inferior_ptid;
+ child_ptid = inferior_thread ()->pending_follow.value.related_pid;
+ parent_pid = ptid_get_lwp (parent_ptid);
+ child_pid = ptid_get_lwp (child_ptid);
/* We're already attached to the parent, by default. */
old_chain = save_inferior_ptid ();
- inferior_ptid = ptid_build (child_pid, child_pid, 0);
+ inferior_ptid = child_ptid;
child_lp = add_lwp (inferior_ptid);
child_lp->stopped = 1;
child_lp->last_resume_kind = resume_stop;
@@ -457,7 +456,7 @@ linux_child_follow_fork (struct target_ops *ops, int follow_child,
{
struct lwp_info *parent_lp;
- parent_lp = find_lwp_pid (pid_to_ptid (parent_pid));
+ parent_lp = find_lwp_pid (parent_ptid);
gdb_assert (linux_supports_tracefork () >= 0);
if (linux_supports_tracevforkdone ())