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From: Nam Cao <namcao@linutronix.de>
To: Gabriele Monaco <gmonaco@redhat.com>
Cc: linux-kernel@vger.kernel.org,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-trace-kernel@vger.kernel.org,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Tomas Glozar <tglozar@redhat.com>, Juri Lelli <jlelli@redhat.com>,
	Clark Williams <williams@redhat.com>,
	John Kacur <jkacur@redhat.com>
Subject: Re: [PATCH v3 11/17] rv: Retry when da monitor detects race conditions
Date: Wed, 16 Jul 2025 10:45:20 +0200	[thread overview]
Message-ID: <20250716084520._QLbd5AY@linutronix.de> (raw)
In-Reply-To: <f7028488e9d820848955de87ead3ec619fe5dbec.camel@redhat.com>

On Wed, Jul 16, 2025 at 10:38:11AM +0200, Gabriele Monaco wrote:
> On Wed, 2025-07-16 at 10:27 +0200, Nam Cao wrote:
> > Can't you bring the monitor back to the init state, and start over
> > again?
> > 
> > I think "da_mon->monitoring = 0;" does the trick?
> > 
> 
> Yes you can, but I wouldn't do so silently.

Why not? The absolute worst that we get, is the rare case where a bug
appears at the exact same time. In that case, we would get a false
negative.

And I think that is really really rare.

> I'd say the cleanest approach without reaction is to still return false
> for the system to do all the cleanup but trace the event or, at the
> very least, print a warning.
> 
> But you're right, this is more relevant for who develops the monitor
> rather than for the user, so should probably be tracked separately.

Yes, if you really want to emit some sort of warning here, it should be
absolutely clear that the monitor itself is having a hiccup, not the
monitored kernel.

Nam

  reply	other threads:[~2025-07-16  8:45 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20250715071434.22508-1-gmonaco@redhat.com>
2025-07-15  7:14 ` [PATCH v3 01/17] tools/rv: Do not skip idle in trace Gabriele Monaco
2025-07-16 11:50   ` Peter Zijlstra
2025-07-16 12:18     ` Gabriele Monaco
2025-07-16 12:41       ` Peter Zijlstra
2025-07-16 13:05         ` Gabriele Monaco
2025-07-16 13:08           ` Peter Zijlstra
2025-07-16 13:13             ` Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 02/17] tools/rv: Stop gracefully also on SIGTERM Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 03/17] rv: Add da_handle_start_run_event_ to per-task monitors Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 04/17] rv: Remove trailing whitespace from tracepoint string Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 05/17] rv: Return init error when registering monitors Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 06/17] rv: Use strings in da monitors tracepoints Gabriele Monaco
2025-07-15 14:11   ` Nam Cao
2025-07-15  7:14 ` [PATCH v3 07/17] rv: Adjust monitor dependencies Gabriele Monaco
2025-07-16  8:19   ` Nam Cao
2025-07-16  8:30     ` Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 08/17] verification/rvgen: Organise Kconfig entries for nested monitors Gabriele Monaco
2025-07-15 14:48   ` Nam Cao
2025-07-16  7:40     ` Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 09/17] tools/dot2c: Fix generated files going over 100 column limit Gabriele Monaco
2025-07-15 15:01   ` Nam Cao
     [not found]     ` <d69862275becf1d296c80a08b29b2081857a85a1.camel@redhat.com>
2025-07-16  9:34       ` Nam Cao
2025-07-15  7:14 ` [PATCH v3 10/17] rv: " Gabriele Monaco
2025-07-15 15:08   ` Nam Cao
2025-07-15 15:24     ` Gabriele Monaco
2025-07-16  8:13       ` Nam Cao
2025-07-16  9:07         ` Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 11/17] rv: Retry when da monitor detects race conditions Gabriele Monaco
2025-07-15 15:23   ` Nam Cao
2025-07-16  8:20     ` Gabriele Monaco
2025-07-16  8:27       ` Nam Cao
2025-07-16  8:38         ` Gabriele Monaco
2025-07-16  8:45           ` Nam Cao [this message]
2025-07-16  8:59             ` Gabriele Monaco
2025-07-16  9:02               ` Nam Cao
2025-07-15  7:14 ` [PATCH v3 12/17] sched: Adapt sched tracepoints for RV task model Gabriele Monaco
2025-07-16 12:38   ` Peter Zijlstra
2025-07-16 13:40     ` Gabriele Monaco
2025-07-16 13:45       ` Peter Zijlstra
2025-07-16 14:07         ` Gabriele Monaco
2025-07-16 14:19           ` Peter Zijlstra
2025-07-16 14:38             ` Gabriele Monaco
2025-07-16 15:31               ` Peter Zijlstra
2025-07-16 16:14                 ` Gabriele Monaco
2025-07-16 15:09     ` Gabriele Monaco
2025-07-16 15:47       ` Peter Zijlstra
2025-07-15  7:14 ` [PATCH v3 13/17] rv: Adapt the sco monitor to the new set_state Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 14/17] rv: Extend snroc model Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 15/17] rv: Replace tss monitor with more complete sts Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 16/17] rv: Add nrp and sssw per-task monitors Gabriele Monaco
2025-07-15  7:14 ` [PATCH v3 17/17] rv: Add opid per-cpu monitor Gabriele Monaco
2025-07-16  9:38   ` Nam Cao
2025-07-16 10:00     ` Gabriele Monaco
2025-07-18 10:26     ` Gabriele Monaco

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