[v4,0/3] Minor fixes to UFS error handling

This series mainly fixes below two things which come along with UFS error
handling in some corner cases.
[1] Concurrency problems btw err_handler and paths like system suspend/resume/shutdown and async scan.
[2] Race condition btw UFS error recovery and task abort which happens to W-LU during suspend/resume/shutdown.

The 1st change is tested with error/fault injections to power mode change
operations during system PM operations and async scan. The 2nd change is
tested by mimicing SSU cmd timeout during suspend/resume/shutdown. The 3rd
one is just a minor change to a check condition in IRQ handler such that
the driver can dump host regs when AH8 error happens.

Change since v3:
- Slightly updated some commit msg lines, no code changes.

Change since v2:
- Added one more minor change into this series.

Change since v1:
- Removed Change-Id from commit msg

Can Guo (3):
  scsi: ufs: Serialize eh_work with system PM events and async scan
  scsi: ufs: Fix a race condition between ufshcd_abort and eh_work
  scsi: ufs: Print host regs in IRQ handler when AH8 error happens

 drivers/scsi/ufs/ufshcd.c | 122 ++++++++++++++++++++++++++++++++--------------
 drivers/scsi/ufs/ufshcd.h |   3 ++
 2 files changed, 88 insertions(+), 37 deletions(-)

On 2020-12-02 15:31, Stanley Chu wrote:
> Hi Can,
> 
> On Tue, 2020-12-01 at 19:47 -0800, Can Guo wrote:
>> Serialize eh_work with system PM events and async scan to make sure 
>> eh_work
>> does not run in parallel with them.
>> 
>> Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
>> Reviewed-by: Hongwu Su<hongwus@codeaurora.org>
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> ---
>>  drivers/scsi/ufs/ufshcd.c | 64 
>> +++++++++++++++++++++++++++++------------------
>>  drivers/scsi/ufs/ufshcd.h |  1 +
>>  2 files changed, 41 insertions(+), 24 deletions(-)
>> 
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 1d8134e..7e764e8 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -5597,7 +5597,9 @@ static inline void 
>> ufshcd_schedule_eh_work(struct ufs_hba *hba)
>>  static void ufshcd_err_handling_prepare(struct ufs_hba *hba)
>>  {
>>  	pm_runtime_get_sync(hba->dev);
>> -	if (pm_runtime_suspended(hba->dev)) {
>> +	if (pm_runtime_status_suspended(hba->dev) || hba->is_sys_suspended) 
>> {
>> +		enum ufs_pm_op pm_op;
>> +
>>  		/*
>>  		 * Don't assume anything of pm_runtime_get_sync(), if
>>  		 * resume fails, irq and clocks can be OFF, and powers
>> @@ -5612,7 +5614,8 @@ static void ufshcd_err_handling_prepare(struct 
>> ufs_hba *hba)
>>  		if (!ufshcd_is_clkgating_allowed(hba))
>>  			ufshcd_setup_clocks(hba, true);
>>  		ufshcd_release(hba);
>> -		ufshcd_vops_resume(hba, UFS_RUNTIME_PM);
>> +		pm_op = hba->is_sys_suspended ? UFS_RUNTIME_PM : UFS_SYSTEM_PM;
> 
> Perhaps typo here? Shall be as below?
> 
> pm_op = hba->is_sys_suspended ? UFS_SYSTEM_PM : UFS_RUNTIME_PM;
> 
> Otherwise looks good to me.

You are right. Will update it in next version.

Thanks,

Can Guo.

> 
> Thanks,
> Stanley Chu
> 
>> +		ufshcd_vops_resume(hba, pm_op);
>>  	} else {
>>  		ufshcd_hold(hba, false);
>>  		if (hba->clk_scaling.is_allowed) {
>> @@ -5633,7 +5636,7 @@ static void ufshcd_err_handling_unprepare(struct 
>> ufs_hba *hba)
>> 
>>  static inline bool ufshcd_err_handling_should_stop(struct ufs_hba 
>> *hba)
>>  {
>> -	return (hba->ufshcd_state == UFSHCD_STATE_ERROR ||
>> +	return (!hba->is_powered || hba->ufshcd_state == UFSHCD_STATE_ERROR 
>> ||
>>  		(!(hba->saved_err || hba->saved_uic_err || hba->force_reset ||
>>  			ufshcd_is_link_broken(hba))));
>>  }
>> @@ -5646,6 +5649,7 @@ static void ufshcd_recover_pm_error(struct 
>> ufs_hba *hba)
>>  	struct request_queue *q;
>>  	int ret;
>> 
>> +	hba->is_sys_suspended = false;
>>  	/*
>>  	 * Set RPM status of hba device to RPM_ACTIVE,
>>  	 * this also clears its runtime error.
>> @@ -5704,11 +5708,13 @@ static void ufshcd_err_handler(struct 
>> work_struct *work)
>> 
>>  	hba = container_of(work, struct ufs_hba, eh_work);
>> 
>> +	down(&hba->eh_sem);
>>  	spin_lock_irqsave(hba->host->host_lock, flags);
>>  	if (ufshcd_err_handling_should_stop(hba)) {
>>  		if (hba->ufshcd_state != UFSHCD_STATE_ERROR)
>>  			hba->ufshcd_state = UFSHCD_STATE_OPERATIONAL;
>>  		spin_unlock_irqrestore(hba->host->host_lock, flags);
>> +		up(&hba->eh_sem);
>>  		return;
>>  	}
>>  	ufshcd_set_eh_in_progress(hba);
>> @@ -5716,20 +5722,18 @@ static void ufshcd_err_handler(struct 
>> work_struct *work)
>>  	ufshcd_err_handling_prepare(hba);
>>  	spin_lock_irqsave(hba->host->host_lock, flags);
>>  	ufshcd_scsi_block_requests(hba);
>> -	/*
>> -	 * A full reset and restore might have happened after preparation
>> -	 * is finished, double check whether we should stop.
>> -	 */
>> -	if (ufshcd_err_handling_should_stop(hba)) {
>> -		if (hba->ufshcd_state != UFSHCD_STATE_ERROR)
>> -			hba->ufshcd_state = UFSHCD_STATE_OPERATIONAL;
>> -		goto out;
>> -	}
>>  	hba->ufshcd_state = UFSHCD_STATE_RESET;
>> 
>>  	/* Complete requests that have door-bell cleared by h/w */
>>  	ufshcd_complete_requests(hba);
>> 
>> +	/*
>> +	 * A full reset and restore might have happened after preparation
>> +	 * is finished, double check whether we should stop.
>> +	 */
>> +	if (ufshcd_err_handling_should_stop(hba))
>> +		goto skip_err_handling;
>> +
>>  	if (hba->dev_quirks & UFS_DEVICE_QUIRK_RECOVERY_FROM_DL_NAC_ERRORS) 
>> {
>>  		bool ret;
>> 
>> @@ -5737,17 +5741,10 @@ static void ufshcd_err_handler(struct 
>> work_struct *work)
>>  		/* release the lock as ufshcd_quirk_dl_nac_errors() may sleep */
>>  		ret = ufshcd_quirk_dl_nac_errors(hba);
>>  		spin_lock_irqsave(hba->host->host_lock, flags);
>> -		if (!ret && !hba->force_reset && ufshcd_is_link_active(hba))
>> +		if (!ret && ufshcd_err_handling_should_stop(hba))
>>  			goto skip_err_handling;
>>  	}
>> 
>> -	if (hba->force_reset || ufshcd_is_link_broken(hba) ||
>> -	    ufshcd_is_saved_err_fatal(hba) ||
>> -	    ((hba->saved_err & UIC_ERROR) &&
>> -	     (hba->saved_uic_err & (UFSHCD_UIC_DL_NAC_RECEIVED_ERROR |
>> -				    UFSHCD_UIC_DL_TCx_REPLAY_ERROR))))
>> -		needs_reset = true;
>> -
>>  	if ((hba->saved_err & (INT_FATAL_ERRORS | UFSHCD_UIC_HIBERN8_MASK)) 
>> ||
>>  	    (hba->saved_uic_err &&
>>  	     (hba->saved_uic_err != UFSHCD_UIC_PA_GENERIC_ERROR))) {
>> @@ -5767,8 +5764,14 @@ static void ufshcd_err_handler(struct 
>> work_struct *work)
>>  	 * transfers forcefully because they will get cleared during
>>  	 * host reset and restore
>>  	 */
>> -	if (needs_reset)
>> +	if (hba->force_reset || ufshcd_is_link_broken(hba) ||
>> +	    ufshcd_is_saved_err_fatal(hba) ||
>> +	    ((hba->saved_err & UIC_ERROR) &&
>> +	     (hba->saved_uic_err & (UFSHCD_UIC_DL_NAC_RECEIVED_ERROR |
>> +				    UFSHCD_UIC_DL_TCx_REPLAY_ERROR)))) {
>> +		needs_reset = true;
>>  		goto do_reset;
>> +	}
>> 
>>  	/*
>>  	 * If LINERESET was caught, UFS might have been put to PWM mode,
>> @@ -5876,12 +5879,11 @@ static void ufshcd_err_handler(struct 
>> work_struct *work)
>>  			dev_err_ratelimited(hba->dev, "%s: exit: saved_err 0x%x 
>> saved_uic_err 0x%x",
>>  			    __func__, hba->saved_err, hba->saved_uic_err);
>>  	}
>> -
>> -out:
>>  	ufshcd_clear_eh_in_progress(hba);
>>  	spin_unlock_irqrestore(hba->host->host_lock, flags);
>>  	ufshcd_scsi_unblock_requests(hba);
>>  	ufshcd_err_handling_unprepare(hba);
>> +	up(&hba->eh_sem);
>>  }
>> 
>>  /**
>> @@ -6856,6 +6858,7 @@ static int ufshcd_reset_and_restore(struct 
>> ufs_hba *hba)
>>  	 */
>>  	scsi_report_bus_reset(hba->host, 0);
>>  	if (err) {
>> +		hba->ufshcd_state = UFSHCD_STATE_ERROR;
>>  		hba->saved_err |= saved_err;
>>  		hba->saved_uic_err |= saved_uic_err;
>>  	}
>> @@ -7704,8 +7707,10 @@ static void ufshcd_async_scan(void *data, 
>> async_cookie_t cookie)
>>  	struct ufs_hba *hba = (struct ufs_hba *)data;
>>  	int ret;
>> 
>> +	down(&hba->eh_sem);
>>  	/* Initialize hba, detect and initialize UFS device */
>>  	ret = ufshcd_probe_hba(hba, true);
>> +	up(&hba->eh_sem);
>>  	if (ret)
>>  		goto out;
>> 
>> @@ -8718,6 +8723,7 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
>>  	int ret = 0;
>>  	ktime_t start = ktime_get();
>> 
>> +	down(&hba->eh_sem);
>>  	if (!hba || !hba->is_powered)
>>  		return 0;
>> 
>> @@ -8748,6 +8754,8 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
>>  		hba->curr_dev_pwr_mode, hba->uic_link_state);
>>  	if (!ret)
>>  		hba->is_sys_suspended = true;
>> +	else
>> +		up(&hba->eh_sem);
>>  	return ret;
>>  }
>>  EXPORT_SYMBOL(ufshcd_system_suspend);
>> @@ -8764,8 +8772,10 @@ int ufshcd_system_resume(struct ufs_hba *hba)
>>  	int ret = 0;
>>  	ktime_t start = ktime_get();
>> 
>> -	if (!hba)
>> +	if (!hba) {
>> +		up(&hba->eh_sem);
>>  		return -EINVAL;
>> +	}
>> 
>>  	if (!hba->is_powered || pm_runtime_suspended(hba->dev))
>>  		/*
>> @@ -8781,6 +8791,7 @@ int ufshcd_system_resume(struct ufs_hba *hba)
>>  		hba->curr_dev_pwr_mode, hba->uic_link_state);
>>  	if (!ret)
>>  		hba->is_sys_suspended = false;
>> +	up(&hba->eh_sem);
>>  	return ret;
>>  }
>>  EXPORT_SYMBOL(ufshcd_system_resume);
>> @@ -8872,6 +8883,7 @@ int ufshcd_shutdown(struct ufs_hba *hba)
>>  {
>>  	int ret = 0;
>> 
>> +	down(&hba->eh_sem);
>>  	if (!hba->is_powered)
>>  		goto out;
>> 
>> @@ -8888,6 +8900,8 @@ int ufshcd_shutdown(struct ufs_hba *hba)
>>  out:
>>  	if (ret)
>>  		dev_err(hba->dev, "%s failed, err %d\n", __func__, ret);
>> +	hba->is_powered = false;
>> +	up(&hba->eh_sem);
>>  	/* allow force shutdown even in case of errors */
>>  	return 0;
>>  }
>> @@ -9082,6 +9096,8 @@ int ufshcd_init(struct ufs_hba *hba, void 
>> __iomem *mmio_base, unsigned int irq)
>>  	INIT_WORK(&hba->eh_work, ufshcd_err_handler);
>>  	INIT_WORK(&hba->eeh_work, ufshcd_exception_event_handler);
>> 
>> +	sema_init(&hba->eh_sem, 1);
>> +
>>  	/* Initialize UIC command mutex */
>>  	mutex_init(&hba->uic_cmd_mutex);
>> 
>> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
>> index 47eb143..1e680bf 100644
>> --- a/drivers/scsi/ufs/ufshcd.h
>> +++ b/drivers/scsi/ufs/ufshcd.h
>> @@ -728,6 +728,7 @@ struct ufs_hba {
>>  	u32 intr_mask;
>>  	u16 ee_ctrl_mask;
>>  	bool is_powered;
>> +	struct semaphore eh_sem;
>> 
>>  	/* Work Queues */
>>  	struct workqueue_struct *eh_wq;