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From: Daniel Bristot de Oliveira <bristot@kernel.org>
To: Nikita Yushchenko <nikita.yushchenko@virtuozzo.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org, kernel@openvz.org
Subject: Re: [PATCH v2] tracing/osnoise: Properly unhook events if start_per_cpu_kthreads() fails
Date: Mon, 10 Jan 2022 08:37:52 +0100	[thread overview]
Message-ID: <b8c59498-8ee2-0049-e215-93ed082aef0f@kernel.org> (raw)
In-Reply-To: <20220109153459.3701773-1-nikita.yushchenko@virtuozzo.com>

On 1/9/22 16:34, Nikita Yushchenko wrote:
> If start_per_cpu_kthreads() called from osnoise_workload_start() returns
> error, event hooks are left in broken state: unhook_irq_events() called
> but unhook_thread_events() and unhook_softirq_events() not called, and
> trace_osnoise_callback_enabled flag not cleared.
> 
> On the next tracer enable, hooks get not installed due to
> trace_osnoise_callback_enabled flag.
> 
> And on the further tracer disable an attempt to remove non-installed
> hooks happened, hitting a WARN_ON_ONCE() in tracepoint_remove_func().
> 
> Fix the error path by adding the missing part of cleanup.
> While at this, introduce osnoise_unhook_events() to avoid code
> duplication between this error path and normal tracer disable.
> 
> Fixes: bce29ac9ce0b ("trace: Add osnoise tracer")
> Signed-off-by: Nikita Yushchenko <nikita.yushchenko@virtuozzo.com>

Acked-by: Daniel Bristot de Oliveira <bristot@kernel.org>

Thanks Nikita!
-- Daniel

      reply	other threads:[~2022-01-10  7:46 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-09 15:34 [PATCH v2] tracing/osnoise: Properly unhook events if start_per_cpu_kthreads() fails Nikita Yushchenko
2022-01-10  7:37 ` Daniel Bristot de Oliveira [this message]

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