linux-kernel - Re: [PATCH v2 12/28] coresight: sysfs: Validate CPU online status for per-CPU sources

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Message-ID: <aGUsT6gMJkYDbGPG@e129823.arm.com>
Date: Wed, 2 Jul 2025 13:55:44 +0100
From: Yeoreum Yun <yeoreum.yun@....com>
To: Leo Yan <leo.yan@....com>
Cc: Suzuki K Poulose <suzuki.poulose@....com>,
	Mike Leach <mike.leach@...aro.org>,
	James Clark <james.clark@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Yabin Cui <yabinc@...gle.com>, Keita Morisaki <keyz@...gle.com>,
	Yuanfang Zhang <quic_yuanfang@...cinc.com>,
	coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 12/28] coresight: sysfs: Validate CPU online status
 for per-CPU sources

Reviewed-by: Yeoreum Yun <yeoreum.yun@....com>

> The current SysFS flow first enables the links and sink, then rolls back
> to disable them if the source fails to enable. This failure can occur if
> the associated CPU is offline, which causes the SMP call to fail.
>
> Validate whether the associated CPU is online for a per-CPU tracer. If
> the CPU is offline, return -ENODEV and bail out.
>
> Signed-off-by: Leo Yan <leo.yan@....com>
> ---
>  drivers/hwtracing/coresight/coresight-sysfs.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c
> index feadaf065b5318c8426aa53420b8e5f67a258683..14ee15297b98115122068cbe932f0b2ce004b77e 100644
> --- a/drivers/hwtracing/coresight/coresight-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-sysfs.c
> @@ -161,6 +161,9 @@ static int coresight_validate_source_sysfs(struct coresight_device *csdev,
>  		return -EINVAL;
>  	}
>
> +	if (coresight_is_percpu_source(csdev) && !cpu_online(csdev->cpu))
> +		return -ENODEV;
> +
>  	return 0;
>  }
>
>
> --
> 2.34.1
>

--
Sincerely,
Yeoreum Yun