Re: [PATCH] scsi: ufs: Start the RTC update work later

[Neil Armstrong <neil.armstrong@linaro.org>]

On 31/10/2024 22:26, Bart Van Assche wrote:
> The RTC update work involves runtime resuming the UFS controller. Hence,
> only start the RTC update work after runtime power management in the UFS
> driver has been fully initialized. This patch fixes the following kernel
> crash:
> 
> Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
> Workqueue: events ufshcd_rtc_work
> Call trace:
>   _raw_spin_lock_irqsave+0x34/0x8c (P)
>   pm_runtime_get_if_active+0x24/0x9c (L)
>   pm_runtime_get_if_active+0x24/0x9c
>   ufshcd_rtc_work+0x138/0x1b4
>   process_one_work+0x148/0x288
>   worker_thread+0x2cc/0x3d4
>   kthread+0x110/0x114
>   ret_from_fork+0x10/0x20
> 
> Reported-by: Neil Armstrong <neil.armstrong@linaro.org>
> Closes: https://lore.kernel.org/linux-scsi/0c0bc528-fdc2-4106-bc99-f23ae377f6f5@linaro.org/
> Fixes: 6bf999e0eb41 ("scsi: ufs: core: Add UFS RTC support")
> Cc: Bean Huo <beanhuo@micron.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>   drivers/ufs/core/ufshcd.c | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 585557eaa9a2..ed82ff329314 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -8633,6 +8633,14 @@ static int ufshcd_add_lus(struct ufs_hba *hba)
>   		ufshcd_init_clk_scaling_sysfs(hba);
>   	}
>   
> +	/*
> +	 * The RTC update code accesses the hba->ufs_device_wlun->sdev_gendev
> +	 * pointer and hence must only be started after the WLUN pointer has
> +	 * been initialized by ufshcd_scsi_add_wlus().
> +	 */
> +	schedule_delayed_work(&hba->ufs_rtc_update_work,
> +			      msecs_to_jiffies(UFS_RTC_UPDATE_INTERVAL_MS));
> +
>   	ufs_bsg_probe(hba);
>   	scsi_scan_host(hba->host);
>   
> @@ -8727,8 +8735,6 @@ static int ufshcd_post_device_init(struct ufs_hba *hba)
>   	ufshcd_force_reset_auto_bkops(hba);
>   
>   	ufshcd_set_timestamp_attr(hba);
> -	schedule_delayed_work(&hba->ufs_rtc_update_work,
> -			      msecs_to_jiffies(UFS_RTC_UPDATE_INTERVAL_MS));
>   
>   	if (!hba->max_pwr_info.is_valid)
>   		return 0;

Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-HDK

Thanks!
Neil