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[patch] Fix remote.c incorrectly using pop_target (wrt btrace)
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: gdb-patches at sourceware dot org
- Cc: "Metzger, Markus T" <markus dot t dot metzger at intel dot com>
- Date: Mon, 11 Mar 2013 18:28:36 +0100
- Subject: [patch] Fix remote.c incorrectly using pop_target (wrt btrace)
Hi,
with the btrace patchset checked in one may get stuck when using btrace and
gdbserver:
./gdbserver :1234 true
./gdb true -ex 'target remote localhost:1234' -ex 'set debug remote 1' -ex 'record btrace'
(gdb) stepi
Sending packet: $qTStatus#49...qTStatus: Remote connection closed
Sending packet: $Z0,7ffff7debd10,1#09...Sending packet: $QPassSignals:e;10;14;17;1a;1b;1c;21;24;25;2c;4c;#5f...0x00007ffff7ddd420 in _start () from /lib64/ld-linux-x86-64.so.2
putpkt: write failed: Broken pipe.
(gdb) q
A debugging session is active.
Inferior 1 [process 26817] will be killed.
Quit anyway? (y or n) y
Sending packet: $qTStatus#49...putpkt: write failed: Broken pipe.
(gdb) _
as discussed in:
RE: Crash of GDB with gdbserver btrace enabled [Re: [patch v9 00/23] branch tracing support for Atom]
http://sourceware.org/ml/gdb-patches/2013-03/msg00296.html
Message-ID: <A78C989F6D9628469189715575E55B2307B9C2F6@IRSMSX102.ger.corp.intel.com>
From: "Metzger, Markus T" <markus.t.metzger@intel.com>
with the fix below:
(gdb) stepi
Sending packet: $qTStatus#49...qTStatus: You can't do that when your target is `record-btrace'
PC register is not available
(gdb) stepi
The program is not being run.
(gdb) q
$ _
Those two removed pop_target calls around
target_preopen (from_tty);
unpush_target (target);
were redundant as they were added by:
commit ef378e83937c25e9da9c4e545bb1a8bb5fd767f1
Author: Daniel Jacobowitz <dan@debian.org>
Date: Wed Jan 30 00:51:50 2008 +0000
but later target_preopen started removing all the targets in target_preopen by:
commit 3db54b199473ba136a4821c420f85096ff17e98e
Author: Pedro Alves <pedro@codesourcery.com>
Date: Mon Aug 18 23:12:39 2008 +0000
No regressions on {x86_64,x86_64-m32,i686}-fedora19pre-linux-gnu and with
gdbserver.
I would like to get it checked in for 7.6 is it is some sort of regression
from btrace.
Thanks,
Jan
gdb/
2013-03-11 Jan Kratochvil <jan.kratochvil@redhat.com>
* remote.c (remote_unpush_target): New function.
(remote_open_1): Remove two pop_target calls, update one comment, add
comment to target_preopen call. Replace pop_target call by
remote_unpush_target call.
(interrupt_query, readchar, getpkt_or_notif_sane_1): Replace
pop_target calls by remote_unpush_target calls.
diff --git a/gdb/remote.c b/gdb/remote.c
index 8fc6b85..6e6c0d6 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -4188,6 +4188,14 @@ remote_query_supported (void)
}
}
+/* Remove any of the remote.c targets from target stack. */
+
+static void
+remote_unpush_target (void)
+{
+ unpush_target (&remote_ops);
+ unpush_target (&extended_remote_ops);
+}
static void
remote_open_1 (char *name, int from_tty,
@@ -4205,30 +4213,18 @@ remote_open_1 (char *name, int from_tty,
wait_forever_enabled_p = 1;
/* If we're connected to a running target, target_preopen will kill it.
- But if we're connected to a target system with no running process,
- then we will still be connected when it returns. Ask this question
- first, before target_preopen has a chance to kill anything. */
+ Ask this question first, before target_preopen has a chance to kill
+ anything. */
if (remote_desc != NULL && !have_inferiors ())
{
- if (!from_tty
- || query (_("Already connected to a remote target. Disconnect? ")))
- pop_target ();
- else
+ if (from_tty
+ && !query (_("Already connected to a remote target. Disconnect? ")))
error (_("Still connected."));
}
+ /* Here the possibly existing remote target gets unpushed. */
target_preopen (from_tty);
- unpush_target (target);
-
- /* This time without a query. If we were connected to an
- extended-remote target and target_preopen killed the running
- process, we may still be connected. If we are starting "target
- remote" now, the extended-remote target will not have been
- removed by unpush_target. */
- if (remote_desc != NULL && !have_inferiors ())
- pop_target ();
-
/* Make sure we send the passed signals list the next time we resume. */
xfree (last_pass_packet);
last_pass_packet = NULL;
@@ -4348,7 +4344,7 @@ remote_open_1 (char *name, int from_tty,
/* Pop the partially set up target - unless something else did
already before throwing the exception. */
if (remote_desc != NULL)
- pop_target ();
+ remote_unpush_target ();
if (target_async_permitted)
wait_forever_enabled_p = 1;
throw_exception (ex);
@@ -5096,7 +5092,7 @@ interrupt_query (void)
if (query (_("Interrupted while waiting for the program.\n\
Give up (and stop debugging it)? ")))
{
- pop_target ();
+ remote_unpush_target ();
deprecated_throw_reason (RETURN_QUIT);
}
}
@@ -7051,11 +7047,11 @@ readchar (int timeout)
switch ((enum serial_rc) ch)
{
case SERIAL_EOF:
- pop_target ();
+ remote_unpush_target ();
error (_("Remote connection closed"));
/* no return */
case SERIAL_ERROR:
- pop_target ();
+ remote_unpush_target ();
perror_with_name (_("Remote communication error. "
"Target disconnected."));
/* no return */
@@ -7579,7 +7575,7 @@ getpkt_or_notif_sane_1 (char **buf, long *sizeof_buf, int forever,
if (forever) /* Watchdog went off? Kill the target. */
{
QUIT;
- pop_target ();
+ remote_unpush_target ();
error (_("Watchdog timeout has expired. Target detached."));
}
if (remote_debug)