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Date: Tue, 24 Feb 2026 11:06:59 +0000
From: Leo Yan <leo.yan@arm.com>
To: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@arm.com>, James Clark <james.clark@linaro.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
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	Mao Jinlong <quic_jinlmao@quicinc.com>, coresight@lists.linaro.org,
	linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 0/8] coresight: Fix device registration and
 unregistration
Message-ID: <20260224110659.GA4184494@e132581.arm.com>
References: <20260209-arm_coresight_refactor_dev_register-v4-0-62d6042f76f7@arm.com>
 <ad38ffc4-eb0b-4430-8d5e-898a2e66977b@arm.com>
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In-Reply-To: <ad38ffc4-eb0b-4430-8d5e-898a2e66977b@arm.com>

On Mon, Feb 23, 2026 at 01:28:03PM +0000, Suzuki K Poulose wrote:

[...]

> [  827.216924]  Possible unsafe locking scenario:
> [  827.216924]
> [  827.222849]        CPU0                    CPU1
> [  827.227380]        ----                    ----
> [  827.231912]   lock(coresight_mutex);
> [  827.235491]                                lock(ect_mutex);
> [  827.241073]                                lock(coresight_mutex);
> [  827.247176]   lock(ect_mutex);
> [  827.250233]
> [  827.250233]  *** DEADLOCK ***

Thanks for the test, Suzuki.

I have sent a refactor patch to dismiss locking chain:
https://lore.kernel.org/linux-arm-kernel/20260224-arm_coresight_refactor_cti_resource_release-v1-1-ff1b2bca9176@arm.com/T/#u

For recording, I enabled the following configs to reproduce the lockdep
report:

  CONFIG_LOCKUP_DETECTOR
  CONFIG_PROVE_LOCKING

Thanks,
Leo