Re: [PATCH] coresight: cti: disclaim device only when it's claimed

From: Mike Leach
Date: Thu Aug 20 2020 - 04:16:04 EST


On Tue, 18 Aug 2020 at 12:11, Tingwei Zhang <tingwei@xxxxxxxxxxxxxx> wrote:
>
> Coresight_claim_device() is called in cti_starting_cpu() only
> when CTI is enabled while coresight_disclaim_device() is called
> uncontionally in cti_dying_cpu(). This triggered below WARNING.
> Only call disclaim device when CTI device is enabled to fix it.
>
> [ 75.989643] WARNING: CPU: 1 PID: 14 at
> kernel/drivers/hwtracing/coresight/coresight.c:209
> coresight_disclaim_device_unlocked+0x10/0x24
> [ 75.989697] CPU: 1 PID: 14 Comm: migration/1 Not tainted
> 5.9.0-rc1-gff1304be0a05-dirty #21
> [ 75.989709] Hardware name: Thundercomm Dragonboard 845c (DT)
> [ 75.989737] pstate: 80c00085 (Nzcv daIf +PAN +UAO BTYPE=--)
> [ 75.989758] pc : coresight_disclaim_device_unlocked+0x10/0x24
> [ 75.989775] lr : coresight_disclaim_device+0x24/0x38
> [ 75.989783] sp : ffff800011cd3c90
> .
> [ 75.990018] Call trace:
> [ 75.990041] coresight_disclaim_device_unlocked+0x10/0x24
> [ 75.990066] cti_dying_cpu+0x34/0x4c
> [ 75.990101] cpuhp_invoke_callback+0x84/0x1e0
> [ 75.990121] take_cpu_down+0x90/0xe0
> [ 75.990154] multi_cpu_stop+0x134/0x160
> [ 75.990171] cpu_stopper_thread+0xb0/0x13c
> [ 75.990196] smpboot_thread_fn+0x1c4/0x270
> [ 75.990222] kthread+0x128/0x154
> [ 75.990251] ret_from_fork+0x10/0x18
>
> Fixes: e9b880581d55 ("coresight: cti: Add CPU Hotplug handling to CTI driver")
> Signed-off-by: Tingwei Zhang <tingwei@xxxxxxxxxxxxxx>
> ---
> drivers/hwtracing/coresight/coresight-cti.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-cti.c b/drivers/hwtracing/coresight/coresight-cti.c
> index 3ccc703dc940..d6fea6efec71 100644
> --- a/drivers/hwtracing/coresight/coresight-cti.c
> +++ b/drivers/hwtracing/coresight/coresight-cti.c
> @@ -742,7 +742,8 @@ static int cti_dying_cpu(unsigned int cpu)
>
> spin_lock(&drvdata->spinlock);
> drvdata->config.hw_powered = false;
> - coresight_disclaim_device(drvdata->base);
> + if (drvdata->config.hw_enabled)
> + coresight_disclaim_device(drvdata->base);
> spin_unlock(&drvdata->spinlock);
> return 0;
> }
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
Reviewed-by: Mike Leach <mike.leach@xxxxxxxxxx>

--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK