From: Miroslav Benes <[email protected]>
To: Jens Axboe <[email protected]>
Cc: Oleg Nesterov <[email protected]>,
[email protected], [email protected],
[email protected], [email protected],
[email protected]
Subject: Re: [PATCHSET RFC v3 0/6] Add support for TIF_NOTIFY_SIGNAL
Date: Mon, 12 Oct 2020 19:27:48 +0200 (CEST) [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On Sat, 10 Oct 2020, Jens Axboe wrote:
> On 10/9/20 9:21 AM, Jens Axboe wrote:
> > On 10/9/20 2:01 AM, Miroslav Benes wrote:
> >> On Thu, 8 Oct 2020, Oleg Nesterov wrote:
> >>
> >>> On 10/05, Jens Axboe wrote:
> >>>>
> >>>> Hi,
> >>>>
> >>>> The goal is this patch series is to decouple TWA_SIGNAL based task_work
> >>>> from real signals and signal delivery.
> >>>
> >>> I think TIF_NOTIFY_SIGNAL can have more users. Say, we can move
> >>> try_to_freeze() from get_signal() to tracehook_notify_signal(), kill
> >>> fake_signal_wake_up(), and remove freezing() from recalc_sigpending().
> >>>
> >>> Probably the same for TIF_PATCH_PENDING, klp_send_signals() can use
> >>> set_notify_signal() rather than signal_wake_up().
> >>
> >> Yes, that was my impression from the patch set too, when I accidentally
> >> noticed it.
> >>
> >> Jens, could you CC our live patching ML when you submit v4, please? It
> >> would be a nice cleanup.
> >
> > Definitely, though it'd be v5 at this point. But we really need to get
> > all archs supporting TIF_NOTIFY_SIGNAL first. Once we have that, there's
> > a whole slew of cleanups that'll fall out naturally:
> >
> > - Removal of JOBCTL_TASK_WORK
> > - Removal of special path for TWA_SIGNAL in task_work
> > - TIF_PATCH_PENDING can be converted and then removed
> > - try_to_freeze() cleanup that Oleg mentioned
> >
> > And probably more I'm not thinking of right now :-)
>
> Here's the current series, I took a stab at converting all archs to
> support TIF_NOTIFY_SIGNAL so we have a base to build on top of. Most
> of them were straight forward, but I need someone to fixup powerpc,
> verify arm and s390.
>
> But it's a decent start I think, and means that we can drop various
> bits as is done at the end of the series. I could swap things around
> a bit and avoid having the intermediate step, but I envision that
> getting this in all archs will take a bit longer than just signing off
> on the generic/x86 bits. So probably best to keep the series as it is
> for now, and work on getting the arch bits verified/fixed/tested.
>
> https://git.kernel.dk/cgit/linux-block/log/?h=tif-task_work
Thanks, Jens.
Crude diff for live patching on top of the series is below. Tested only on
x86_64, but it passes the tests without an issue.
Miroslav
---
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index f6310f848f34..3a4beb9395c4 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -9,6 +9,7 @@
#include <linux/cpu.h>
#include <linux/stacktrace.h>
+#include <linux/tracehook.h>
#include "core.h"
#include "patch.h"
#include "transition.h"
@@ -369,9 +370,7 @@ static void klp_send_signals(void)
* Send fake signal to all non-kthread tasks which are
* still not migrated.
*/
- spin_lock_irq(&task->sighand->siglock);
- signal_wake_up(task, 0);
- spin_unlock_irq(&task->sighand->siglock);
+ set_notify_signal(task);
}
}
read_unlock(&tasklist_lock);
diff --git a/kernel/signal.c b/kernel/signal.c
index a15c584a0455..b7cf4eda8611 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -181,8 +181,7 @@ void recalc_sigpending_and_wake(struct task_struct *t)
void recalc_sigpending(void)
{
- if (!recalc_sigpending_tsk(current) && !freezing(current) &&
- !klp_patch_pending(current))
+ if (!recalc_sigpending_tsk(current) && !freezing(current))
clear_thread_flag(TIF_SIGPENDING);
}
next prev parent reply other threads:[~2020-10-12 17:27 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-05 15:04 [PATCHSET RFC v3 0/6] Add support for TIF_NOTIFY_SIGNAL Jens Axboe
2020-10-05 15:04 ` [PATCH 1/6] tracehook: clear TIF_NOTIFY_RESUME in tracehook_notify_resume() Jens Axboe
2020-10-08 12:37 ` Oleg Nesterov
2020-10-08 13:36 ` Jens Axboe
2020-10-05 15:04 ` [PATCH 2/6] kernel: add task_sigpending() helper Jens Axboe
2020-10-08 12:58 ` Oleg Nesterov
2020-10-08 13:36 ` Jens Axboe
2020-10-08 13:24 ` Oleg Nesterov
2020-10-08 13:38 ` Jens Axboe
2020-10-05 15:04 ` [PATCH 3/6] kernel: split syscall restart from signal handling Jens Axboe
2020-10-08 14:21 ` Oleg Nesterov
2020-10-08 14:31 ` Jens Axboe
2020-10-08 14:41 ` Jens Axboe
2020-10-08 14:45 ` Oleg Nesterov
2020-10-08 14:47 ` Jens Axboe
2020-10-05 15:04 ` [PATCH 4/6] kernel: add support for TIF_NOTIFY_SIGNAL Jens Axboe
2020-10-08 13:53 ` Oleg Nesterov
2020-10-08 14:07 ` Jens Axboe
2020-10-08 14:27 ` Oleg Nesterov
2020-10-05 15:04 ` [PATCH 5/6] x86: define _TIF_NOTIFY_SIGNAL Jens Axboe
2020-10-05 15:04 ` [PATCH 6/6] task_work: use TIF_NOTIFY_SIGNAL if available Jens Axboe
2020-10-08 14:56 ` [PATCHSET RFC v3 0/6] Add support for TIF_NOTIFY_SIGNAL Oleg Nesterov
2020-10-08 15:00 ` Jens Axboe
2020-10-09 8:01 ` Miroslav Benes
2020-10-09 15:21 ` Jens Axboe
2020-10-10 16:53 ` Jens Axboe
2020-10-12 17:27 ` Miroslav Benes [this message]
2020-10-13 19:39 ` Jens Axboe
2020-10-13 23:34 ` Thomas Gleixner
2020-10-13 23:37 ` Jens Axboe
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