From: Doug Evans <dje@google.com>
To: Pedro Alves <palves@redhat.com>
Cc: gdb-patches <gdb-patches@sourceware.org>
Subject: Re: [pushed+7.8] Re: [PATCH] Fix "attach" command vs user input race [Re: Regression for attach from stdin [Re: [pushed] Re: [PATCH v6 0/2] enable target-async by default]]
Date: Tue, 29 Jul 2014 22:03:00 -0000 [thread overview]
Message-ID: <CADPb22Qt1ctMb9DZg-ftxeAycTqJAkGjtz10ADkoOiDwLggPow@mail.gmail.com> (raw)
In-Reply-To: <53BD7749.5000800@redhat.com>
On Wed, Jul 9, 2014 at 10:09 AM, Pedro Alves <palves@redhat.com> wrote:
> On 07/09/2014 05:37 PM, Doug Evans wrote:
>
>> spurious change
>
> Fixed.
>
>> I like this a lot better. Thanks.
>> The patch is ok with me, modulo removing the spurious change.
>
> Here's what I pushed to both master and gdb-7.8-branch.
>
> Thanks.
>
> -------------
> From 1fe2833b6dd03602ba86aa334e81466ea9abe66a Mon Sep 17 00:00:00 2001
> From: Pedro Alves <palves@redhat.com>
> Date: Wed, 9 Jul 2014 17:52:58 +0100
> Subject: [PATCH] Fix "attach" command vs user input race
>
> On async targets, a synchronous attach is done like this:
>
> #1 - target_attach is called (PTRACE_ATTACH is issued)
> #2 - a continuation is installed
> #3 - we go back to the event loop
> #4 - target reports stop (SIGSTOP), event loop wakes up, and
> attach continuation is called
> #5 - among other things, the continuation calls
> target_terminal_inferior, which removes stdin from the event
> loop
>
> Note that in #3, GDB is still processing user input. If the user is
> fast enough, e.g., with something like:
>
> echo -e "attach PID\nset xxx=1" | gdb
>
> ... then the "set" command is processed before the attach completes.
>
> We get worse behavior even, if input is a tty and therefore
> readline/editing is enabled, with e.g.,:
>
> (gdb) attach PID\nset xxx=1
>
> we then crash readline/gdb, with:
>
> Attaching to program: attach-wait-input, process 14537
> readline: readline_callback_read_char() called with no handler!
> Aborted
> $
>
> Fix this by calling target_terminal_inferior before #3 above.
>
> The test covers both scenarios by running with editing/readline forced
> to both on and off.
>
> gdb/
> 2014-07-09 Pedro Alves <palves@redhat.com>
>
> * infcmd.c (attach_command_post_wait): Don't call
> target_terminal_inferior here.
> (attach_command): Call it here instead.
>
> gdb/testsuite/
> 2014-07-09 Pedro Alves <palves@redhat.com>
>
> * gdb.base/attach-wait-input.exp: New file.
> * gdb.base/attach-wait-input.c: New file.
Hi.
Is this TODO still needed after this patch?
infcmd.c:
/*
* TODO:
* Should save/restore the tty state since it might be that the
* program to be debugged was started on this tty and it wants
* the tty in some state other than what we want. If it's running
* on another terminal or without a terminal, then saving and
* restoring the tty state is a harmless no-op.
* This only needs to be done if we are attaching to a process.
*/
next prev parent reply other threads:[~2014-07-29 21:48 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-23 20:59 [PATCH v6 0/2] enable target-async by default Pedro Alves
2014-05-23 20:59 ` [PATCH v6 2/2] enable target async by default; separate MI and target notions of async Pedro Alves
2014-05-24 7:03 ` Eli Zaretskii
2014-05-29 13:49 ` Pedro Alves
2014-07-30 18:40 ` Doug Evans
2014-05-23 20:59 ` [PATCH v6 1/2] Make display_gdb_prompt CLI-only Pedro Alves
2014-05-29 13:44 ` [pushed] Re: [PATCH v6 0/2] enable target-async by default Pedro Alves
2014-07-01 16:28 ` Regression for attach from stdin [Re: [pushed] Re: [PATCH v6 0/2] enable target-async by default] Jan Kratochvil
2014-07-02 8:59 ` Mark Wielaard
2014-07-02 9:16 ` Pedro Alves
2014-07-03 15:39 ` Pedro Alves
2014-07-04 13:48 ` [PATCH] Fix "attach" command vs user input race [Re: Regression for attach from stdin [Re: [pushed] Re: [PATCH v6 0/2] enable target-async by default]] Pedro Alves
2014-07-04 21:13 ` Mark Wielaard
2014-07-07 16:39 ` Doug Evans
2014-07-08 15:24 ` Pedro Alves
2014-07-09 16:37 ` Doug Evans
2014-07-09 17:09 ` [pushed+7.8] " Pedro Alves
2014-07-29 22:03 ` Doug Evans [this message]
2014-07-29 23:10 ` Doug Evans
2014-07-30 12:46 ` Pedro Alves
2014-07-30 12:38 ` Pedro Alves
2014-07-30 16:59 ` Doug Evans
2014-08-21 16:34 ` [PUSHED] infcmd.c: Remove stale TODO Pedro Alves
2014-09-03 7:59 ` Regression: GDB stopped on run with attached process (PR 17347) [Re: [pushed+7.8] Re: [PATCH] Fix "attach" command vs user input race [Re: Regression for attach from stdin [Re: [pushed] Re: [PATCH v6 0/2] enable target-async by default]]] Jan Kratochvil
2014-09-03 20:11 ` Regression: GDB stopped on run with attached process (PR 17347) [Re: [pushed+7.8] Re: [PATCH] Fix "attach" command vs user input race Pedro Alves
2014-09-07 19:28 ` Jan Kratochvil
2014-09-08 16:19 ` [PATCH 1/2] testsuite: refactor spawn and wait for attach (was: Re: Regression: GDB stopped on run with attached process) Pedro Alves
2014-09-09 17:29 ` Jan Kratochvil
2014-09-09 17:35 ` [PATCH 1/2] testsuite: refactor spawn and wait for attach Pedro Alves
2014-09-10 21:25 ` Pedro Alves
2014-09-11 12:34 ` Pedro Alves
2014-09-08 16:27 ` Regression: GDB stopped on run with attached process (PR 17347) [Re: [pushed+7.8] Re: [PATCH] Fix "attach" command vs user input race Pedro Alves
2014-09-09 18:25 ` Jan Kratochvil
2014-09-11 12:36 ` Pedro Alves
2014-09-12 7:34 ` [testsuite patch] runaway attach processes [Re: Regression: GDB stopped on run with attached process (PR 17347)] Jan Kratochvil
2014-09-12 10:14 ` Pedro Alves
2014-09-12 11:40 ` [commit] " Jan Kratochvil
2014-07-07 17:02 ` [PATCH] Fix "attach" command vs user input race [Re: Regression for attach from stdin [Re: [pushed] Re: [PATCH v6 0/2] enable target-async by default]] Jan Kratochvil
2014-10-05 14:00 ` Crash regression for annota1.exp w/vDSO debuginfo [Re: [pushed] Re: [PATCH v6 0/2] enable target-async by default] Jan Kratochvil
2014-10-05 14:14 ` Jan Kratochvil
2014-10-05 16:43 ` Jan Kratochvil
2014-10-09 15:48 ` Pedro Alves
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