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Re: problem with new vforkdone stop reply in 7.10
- From: Pedro Alves <palves at redhat dot com>
- To: "Breazeal, Don" <donb at codesourcery dot com>
- Cc: "gdb at sourceware dot org" <gdb at sourceware dot org>
- Date: Tue, 15 Sep 2015 15:51:41 +0100
- Subject: Re: problem with new vforkdone stop reply in 7.10
- Authentication-results: sourceware.org; auth=none
- References: <55F828D9 dot 8050100 at redhat dot com>
On 09/15/2015 03:19 PM, Pedro Alves wrote:
> Hi Don,
>
> Unfortunately, I missed in review that the vforkdone stop reply
> misses indicating the thread ID of the vfork parent which the
> event relates to:
I'm testing this. I wonder whether I'm missing some reason
to keep the vforkdone switch case separate?
At least foll-vfork.exp still passes.
I should split this to a separate patch, but I also noticed that
the TARGET_WAITKIND_EXECD handling checks multi_process instead of
report_exec_events:
- else if (status->kind == TARGET_WAITKIND_EXECD && multi_process)
+ else if (status->kind == TARGET_WAITKIND_EXECD && report_exec_events)
which I think would be the check we want.
Thanks,
Pedro Alves
>From 85989d3ce1cc931aa7025e21952136ef037388a1 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Tue, 15 Sep 2015 15:43:12 +0100
Subject: [PATCH] Fix vforkdone stop reply
The vforkdone stop reply misses indicating the thread ID of the vfork
parent which the event relates to:
@cindex vfork events, remote reply
@item vfork
The packet indicates that @code{vfork} was called, and @var{r}
is the thread ID of the new child process. Refer to
@ref{thread-id syntax} for the format of the @var{thread-id}
field. This packet is only applicable to targets that support
vfork events.
@cindex vforkdone events, remote reply
@item vforkdone
The packet indicates that a child process created by a vfork
has either called @code{exec} or terminated, so that the
address spaces of the parent and child process are no longer
shared. The @var{r} part is ignored. This packet is only
applicable to targets that support vforkdone events.
Unfortunately, this is not just a documentation issue. GDBserver
is really not specifying the thread ID. I noticed because
in non-stop mode, gdb complains:
[Thread 6089.6089] #1 stopped.
#0 0x0000003615a011f0 in ?? ()
0x0000003615a011f0 in ?? ()
(gdb) set debug remote 1
(gdb) c
Continuing.
Sending packet: $QPassSignals:e;10;14;17;1a;1b;1c;21;24;25;2c;4c;#5f...Packet received: OK
Sending packet: $vCont;c:p17c9.17c9#88...Packet received: OK
Notification received: Stop:T05vfork:p17ce.17ce;06:40d7ffffff7f0000;07:30d7ffffff7f0000;10:e4c9eb1536000000;thread:p17c9.17c9;core:2;
Sending packet: $vStopped#55...Packet received: OK
Sending packet: $D;17ce#af...Packet received: OK
Sending packet: $vCont;c:p17c9.17c9#88...Packet received: OK
Notification received: Stop:T05vforkdone:;
No process or thread specified in stop reply: T05vforkdone:;
(gdb)
This is not non-stop-mode-specific, however. Consider e.g., that in
all-stop, you may be debugging more than one process at the same time.
You continue, and both processes vfork. So when you next get a
T05vforkdone, there's no way to tell which of the parent processes is
done with the vfork.
gdb/ChangeLog:
2015-09-15 Pedro Alves <palves@redhat.com>
* remote-utils.c (prepare_resume_reply): Merge
TARGET_WAITKIND_VFORK_DONE switch case with the
TARGET_WAITKIND_FORKED case.
gdb/doc/ChangeLog:
2015-09-15 Pedro Alves <palves@redhat.com>
* gdb.texinfo: Explain that vforkdone's 'r' part indicates the
parent process.
---
gdb/doc/gdb.texinfo | 9 +++++----
gdb/gdbserver/remote-utils.c | 19 ++++++++-----------
2 files changed, 13 insertions(+), 15 deletions(-)
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 395f0d4..3ac8c43 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -35498,10 +35498,11 @@ indicating support.
@cindex vforkdone events, remote reply
@item vforkdone
-The packet indicates that a child process created by a vfork
-has either called @code{exec} or terminated, so that the
-address spaces of the parent and child process are no longer
-shared. The @var{r} part is ignored. This packet is only
+The packet indicates that a child process created by a vfork has
+either called @code{exec} or terminated, so that the address spaces of
+the parent and child process are no longer shared. The @var{r} part is
+the thread ID of the parent process. Refer to @ref{thread-id syntax}
+for the format of the @var{thread-id} field. This packet is only
applicable to targets that support vforkdone events.
This packet should not be sent by default; older @value{GDBN} versions
diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
index ac86dd5..7cf66cc 100644
--- a/gdb/gdbserver/remote-utils.c
+++ b/gdb/gdbserver/remote-utils.c
@@ -1117,6 +1117,7 @@ prepare_resume_reply (char *buf, ptid_t ptid,
case TARGET_WAITKIND_STOPPED:
case TARGET_WAITKIND_FORKED:
case TARGET_WAITKIND_VFORKED:
+ case TARGET_WAITKIND_VFORK_DONE:
case TARGET_WAITKIND_EXECD:
{
struct thread_info *saved_thread;
@@ -1135,7 +1136,13 @@ prepare_resume_reply (char *buf, ptid_t ptid,
buf = write_ptid (buf, status->value.related_pid);
strcat (buf, ";");
}
- else if (status->kind == TARGET_WAITKIND_EXECD && multi_process)
+ else if (status->kind == TARGET_WAITKIND_VFORK_DONE && report_vfork_events)
+ {
+ enum gdb_signal signal = GDB_SIGNAL_TRAP;
+
+ sprintf (buf, "T%02xvforkdone:;", signal);
+ }
+ else if (status->kind == TARGET_WAITKIND_EXECD && report_exec_events)
{
enum gdb_signal signal = GDB_SIGNAL_TRAP;
const char *event = "exec";
@@ -1269,16 +1276,6 @@ prepare_resume_reply (char *buf, ptid_t ptid,
else
sprintf (buf, "X%02x", status->value.sig);
break;
- case TARGET_WAITKIND_VFORK_DONE:
- if (report_vfork_events)
- {
- enum gdb_signal signal = GDB_SIGNAL_TRAP;
-
- sprintf (buf, "T%02xvforkdone:;", signal);
- }
- else
- sprintf (buf, "T%02x", GDB_SIGNAL_0);
- break;
default:
error ("unhandled waitkind");
break;
--
1.9.3