Re: [PATCH v1] ufs: core: fix deadlock when rtc update

On 7/12/24 2:43 AM, peter.wang@mediatek.com wrote:

Three have deadlock when runtime suspend wait flush rtc work, and rtc work call ufshcd_rpm_put_sync to wait runtime resume.

"Three have"? The above description is very hard to understand. Please improve it.

• /* Update RTC only when there are no requests in progress and UFSHCI is operational */
  

• if (!ufshcd_is_ufs_dev_busy(hba) && hba->ufshcd_state == UFSHCD_STATE_OPERATIONAL)

• /*
  

•  * Update RTC only when
  

•  * 1. there are no requests in progress
  

•  * 2. UFSHCI is operational
  

•  * 3. pm operation is not in progress
  

•  */
  

• if (!ufshcd_is_ufs_dev_busy(hba) &&

•    hba->ufshcd_state == UFSHCD_STATE_OPERATIONAL &&
  

•    !hba->pm_op_in_progress)
  

  ufshcd_update_rtc(hba);

if (ufshcd_is_ufs_dev_active(hba) && hba->dev_info.rtc_update_period)

The above seems racy to me. I don't think there is any mechanism that prevents that hba->pm_op_in_progress is set after it has been checked and before ufshcd_update_rtc() is called. Has it been considered to add an ufshcd_rpm_get_sync_nowait() call before the hba->pm_op_in_progress check and a ufshcd_rpm_put_sync() call after the ufshcd_update_rtc() call?

Thanks,

Bart.