From: Oleg Nesterov <oleg@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: jan.kratochvil@redhat.com, vda.linux@googlemail.com,
linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
akpm@linux-foundation.org, indan@nul.nu, bdonlan@gmail.com
Subject: Re: [PATCH 6/9] job control: make task_clear_jobctl_pending() clear TRAPPING automatically
Date: Mon, 16 May 2011 14:25:35 +0200 [thread overview]
Message-ID: <20110516122535.GD4898@redhat.com> (raw)
In-Reply-To: <1305301580-9924-7-git-send-email-tj@kernel.org>
On 05/13, Tejun Heo wrote:
>
> @@ -264,6 +267,9 @@ void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
> mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
>
> task->jobctl &= ~mask;
> +
> + if (!(task->jobctl & JOBCTL_PENDING_MASK))
> + task_clear_jobctl_trapping(task);
> }
So, SIGCONT clears JOBCTL_TRAPPING and wakes up the tracer.
I can't really understand this without seeing the next changes, but
it seems this makes some things worse, although I am not sure.
For example. PTRACE_SEIZE should guarantee the tracee will trap and
report. However, if the tracee is stopped during attach, we can race
with SIGCONT. The previous version had the similar problem afaics, but
it was easy (I think) to fix. Now that SIGCONT clears JOBCTL_TRAPPING
we need more complications.
Oleg.
next prev parent reply other threads:[~2011-05-16 12:26 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-13 15:46 [PATCHSET ptrace] ptrace: prepare for PTRACE_SEIZE/INTERRUPT Tejun Heo
2011-05-13 15:46 ` [PATCH 1/9] job control: reorganize wait_task_stopped() Tejun Heo
2011-05-16 11:56 ` Oleg Nesterov
2011-05-13 15:46 ` [PATCH 2/9] job control: rename signal->group_stop and flags to jobctl and rearrange flags Tejun Heo
2011-05-13 15:46 ` [PATCH 3/9] ptrace: ptrace_check_attach(): rename @kill to @ignore_state and add comments Tejun Heo
2011-05-13 15:46 ` [PATCH 4/9] ptrace: relocate set_current_state(TASK_TRACED) in ptrace_stop() Tejun Heo
2011-05-16 11:57 ` Oleg Nesterov
2011-05-16 13:16 ` Tejun Heo
2011-05-16 15:51 ` Oleg Nesterov
2011-05-16 15:59 ` Tejun Heo
2011-05-16 16:34 ` Oleg Nesterov
2011-05-13 15:46 ` [PATCH 5/9] job control: introduce JOBCTL_PENDING_MASK and task_clear_jobctl_pending() Tejun Heo
2011-05-13 15:46 ` [PATCH 6/9] job control: make task_clear_jobctl_pending() clear TRAPPING automatically Tejun Heo
2011-05-16 12:25 ` Oleg Nesterov [this message]
2011-05-16 13:24 ` Tejun Heo
2011-05-16 16:00 ` Oleg Nesterov
2011-05-16 16:09 ` Tejun Heo
2011-05-13 15:46 ` [PATCH 7/9] ptrace: use bit_waitqueue for TRAPPING instead of wait_chldexit Tejun Heo
2011-05-13 15:46 ` [PATCH 8/9] ptrace: move JOBCTL_TRAPPING wait to wait(2) and ptrace_check_attach() Tejun Heo
2011-05-14 14:22 ` [PATCH UPDATED " Tejun Heo
2011-05-16 12:11 ` Oleg Nesterov
2011-05-16 13:36 ` Tejun Heo
2011-05-16 16:04 ` Oleg Nesterov
2011-05-13 15:46 ` [PATCH 9/9] ptrace: make TRAPPING wait interruptible Tejun Heo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20110516122535.GD4898@redhat.com \
--to=oleg@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=bdonlan@gmail.com \
--cc=indan@nul.nu \
--cc=jan.kratochvil@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=tj@kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=vda.linux@googlemail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).