[PATCH v2 0/3] Two changes of UFS sysfs

[PATCH v2 0/3] Two changes of UFS sysfs

[Bean Huo]

From: Bean Huo <beanhuo@micron.com>

Changelog:

V1---v2:
    1. Add new patch "Let resume callback return -EBUSY after ufshcd_shutdown",
       Because the ufshcd_*_resume still returns successful result 0 after
       ufshcd_shutdown(). Even add handling of the return value of
       pm_runtime_get_sync(), but still there is timeout.

Bean Huo (3):
  scsi: ufs: Replace sprintf and snprintf with sysfs_emit
  scsi: ufs: Add handling of the return value of pm_runtime_get_sync()
  scsi: ufs: Let resume callback return -EBUSY after ufshcd_shutdown

 drivers/scsi/ufs/ufs-sysfs.c | 68 +++++++++++++++++++++++++-----------
 drivers/scsi/ufs/ufshcd.c    | 12 ++++---
 2 files changed, 55 insertions(+), 25 deletions(-)

-- 
2.17.1

[PATCH v2 1/3] scsi: ufs: Replace sprintf and snprintf with sysfs_emit

[Bean Huo]

From: Bean Huo <beanhuo@micron.com>

sprintf and snprintf may cause output defect in sysfs content, it is
better to use new added sysfs_emit function which knows the size of the
temporary buffer.

Reviewed-by: Avri Altman <avri.altman@wdc.com>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Bean Huo <beanhuo@micron.com>
---
 drivers/scsi/ufs/ufs-sysfs.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-sysfs.c b/drivers/scsi/ufs/ufs-sysfs.c
index 08e72b7eef6a..0e1438485133 100644
--- a/drivers/scsi/ufs/ufs-sysfs.c
+++ b/drivers/scsi/ufs/ufs-sysfs.c
@@ -67,7 +67,7 @@ static ssize_t rpm_lvl_show(struct device *dev,
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 
-	return sprintf(buf, "%d\n", hba->rpm_lvl);
+	return sysfs_emit(buf, "%d\n", hba->rpm_lvl);
 }
 
 static ssize_t rpm_lvl_store(struct device *dev,
@@ -81,7 +81,7 @@ static ssize_t rpm_target_dev_state_show(struct device *dev,
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 
-	return sprintf(buf, "%s\n", ufschd_ufs_dev_pwr_mode_to_string(
+	return sysfs_emit(buf, "%s\n", ufschd_ufs_dev_pwr_mode_to_string(
 			ufs_pm_lvl_states[hba->rpm_lvl].dev_state));
 }
 
@@ -90,7 +90,7 @@ static ssize_t rpm_target_link_state_show(struct device *dev,
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 
-	return sprintf(buf, "%s\n", ufschd_uic_link_state_to_string(
+	return sysfs_emit(buf, "%s\n", ufschd_uic_link_state_to_string(
 			ufs_pm_lvl_states[hba->rpm_lvl].link_state));
 }
 
@@ -99,7 +99,7 @@ static ssize_t spm_lvl_show(struct device *dev,
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 
-	return sprintf(buf, "%d\n", hba->spm_lvl);
+	return sysfs_emit(buf, "%d\n", hba->spm_lvl);
 }
 
 static ssize_t spm_lvl_store(struct device *dev,
@@ -113,7 +113,7 @@ static ssize_t spm_target_dev_state_show(struct device *dev,
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 
-	return sprintf(buf, "%s\n", ufschd_ufs_dev_pwr_mode_to_string(
+	return sysfs_emit(buf, "%s\n", ufschd_ufs_dev_pwr_mode_to_string(
 				ufs_pm_lvl_states[hba->spm_lvl].dev_state));
 }
 
@@ -122,7 +122,7 @@ static ssize_t spm_target_link_state_show(struct device *dev,
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 
-	return sprintf(buf, "%s\n", ufschd_uic_link_state_to_string(
+	return sysfs_emit(buf, "%s\n", ufschd_uic_link_state_to_string(
 				ufs_pm_lvl_states[hba->spm_lvl].link_state));
 }
 
@@ -165,7 +165,7 @@ static ssize_t auto_hibern8_show(struct device *dev,
 	ufshcd_release(hba);
 	pm_runtime_put_sync(hba->dev);
 
-	return scnprintf(buf, PAGE_SIZE, "%d\n", ufshcd_ahit_to_us(ahit));
+	return sysfs_emit(buf, "%d\n", ufshcd_ahit_to_us(ahit));
 }
 
 static ssize_t auto_hibern8_store(struct device *dev,
@@ -233,18 +233,18 @@ static ssize_t ufs_sysfs_read_desc_param(struct ufs_hba *hba,
 		return -EINVAL;
 	switch (param_size) {
 	case 1:
-		ret = sprintf(sysfs_buf, "0x%02X\n", *desc_buf);
+		ret = sysfs_emit(sysfs_buf, "0x%02X\n", *desc_buf);
 		break;
 	case 2:
-		ret = sprintf(sysfs_buf, "0x%04X\n",
+		ret = sysfs_emit(sysfs_buf, "0x%04X\n",
 			get_unaligned_be16(desc_buf));
 		break;
 	case 4:
-		ret = sprintf(sysfs_buf, "0x%08X\n",
+		ret = sysfs_emit(sysfs_buf, "0x%08X\n",
 			get_unaligned_be32(desc_buf));
 		break;
 	case 8:
-		ret = sprintf(sysfs_buf, "0x%016llX\n",
+		ret = sysfs_emit(sysfs_buf, "0x%016llX\n",
 			get_unaligned_be64(desc_buf));
 		break;
 	}
@@ -609,7 +609,7 @@ static ssize_t _name##_show(struct device *dev,				\
 				      SD_ASCII_STD);			\
 	if (ret < 0)							\
 		goto out;						\
-	ret = snprintf(buf, PAGE_SIZE, "%s\n", desc_buf);		\
+	ret = sysfs_emit(buf, "%s\n", desc_buf);		\
 out:									\
 	pm_runtime_put_sync(hba->dev);					\
 	kfree(desc_buf);						\
@@ -659,7 +659,7 @@ static ssize_t _name##_show(struct device *dev,				\
 	pm_runtime_put_sync(hba->dev);					\
 	if (ret)							\
 		return -EINVAL;						\
-	return sprintf(buf, "%s\n", flag ? "true" : "false"); \
+	return sysfs_emit(buf, "%s\n", flag ? "true" : "false");	\
 }									\
 static DEVICE_ATTR_RO(_name)
 
@@ -717,7 +717,7 @@ static ssize_t _name##_show(struct device *dev,				\
 	pm_runtime_put_sync(hba->dev);					\
 	if (ret)							\
 		return -EINVAL;						\
-	return sprintf(buf, "0x%08X\n", value);				\
+	return sysfs_emit(buf, "0x%08X\n", value);			\
 }									\
 static DEVICE_ATTR_RO(_name)
 
@@ -856,7 +856,7 @@ static ssize_t dyn_cap_needed_attribute_show(struct device *dev,
 	pm_runtime_put_sync(hba->dev);
 	if (ret)
 		return -EINVAL;
-	return sprintf(buf, "0x%08X\n", value);
+	return sysfs_emit(buf, "0x%08X\n", value);
 }
 static DEVICE_ATTR_RO(dyn_cap_needed_attribute);
 
-- 
2.17.1

[PATCH v2 2/3] scsi: ufs: Add handling of the return value of pm_runtime_get_sync()

[Bean Huo]

From: Bean Huo <beanhuo@micron.com>

The race issue may exist between UFS access in UFS sysfs context and UFS
shutdown, thus will cause pm_runtime_get_sync() resume failure.
Add handling of the return value of pm_runtime_get_sync(). Let it return
in case pm_runtime_get_sync() resume failed.

Signed-off-by: Bean Huo <beanhuo@micron.com>
---
 drivers/scsi/ufs/ufs-sysfs.c | 38 ++++++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-sysfs.c b/drivers/scsi/ufs/ufs-sysfs.c
index 0e1438485133..8e5e36e01bee 100644
--- a/drivers/scsi/ufs/ufs-sysfs.c
+++ b/drivers/scsi/ufs/ufs-sysfs.c
@@ -154,12 +154,17 @@ static ssize_t auto_hibern8_show(struct device *dev,
 				 struct device_attribute *attr, char *buf)
 {
 	u32 ahit;
+	int ret;
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 
 	if (!ufshcd_is_auto_hibern8_supported(hba))
 		return -EOPNOTSUPP;
 
-	pm_runtime_get_sync(hba->dev);
+	ret = pm_runtime_get_sync(hba->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(hba->dev);
+		return ret;
+	}
 	ufshcd_hold(hba, false);
 	ahit = ufshcd_readl(hba, REG_AUTO_HIBERNATE_IDLE_TIMER);
 	ufshcd_release(hba);
@@ -225,7 +230,12 @@ static ssize_t ufs_sysfs_read_desc_param(struct ufs_hba *hba,
 	if (param_size > 8)
 		return -EINVAL;
 
-	pm_runtime_get_sync(hba->dev);
+	ret = pm_runtime_get_sync(hba->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(hba->dev);
+		return ret;
+	}
+
 	ret = ufshcd_read_desc_param(hba, desc_id, desc_index,
 				param_offset, desc_buf, param_size);
 	pm_runtime_put_sync(hba->dev);
@@ -594,7 +604,11 @@ static ssize_t _name##_show(struct device *dev,				\
 	desc_buf = kzalloc(QUERY_DESC_MAX_SIZE, GFP_ATOMIC);		\
 	if (!desc_buf)                                                  \
 		return -ENOMEM;                                         \
-	pm_runtime_get_sync(hba->dev);					\
+	ret = pm_runtime_get_sync(hba->dev);				\
+	if (ret < 0) {							\
+		pm_runtime_put_noidle(hba->dev);			\
+		return ret;						\
+	}								\
 	ret = ufshcd_query_descriptor_retry(hba,			\
 		UPIU_QUERY_OPCODE_READ_DESC, QUERY_DESC_IDN_DEVICE,	\
 		0, 0, desc_buf, &desc_len);				\
@@ -653,7 +667,11 @@ static ssize_t _name##_show(struct device *dev,				\
 	struct ufs_hba *hba = dev_get_drvdata(dev);			\
 	if (ufshcd_is_wb_flags(QUERY_FLAG_IDN##_uname))			\
 		index = ufshcd_wb_get_query_index(hba);			\
-	pm_runtime_get_sync(hba->dev);					\
+	ret = pm_runtime_get_sync(hba->dev);				\
+	if (ret < 0) {							\
+		pm_runtime_put_noidle(hba->dev);			\
+		return ret;						\
+	}								\
 	ret = ufshcd_query_flag(hba, UPIU_QUERY_OPCODE_READ_FLAG,	\
 		QUERY_FLAG_IDN##_uname, index, &flag);			\
 	pm_runtime_put_sync(hba->dev);					\
@@ -711,7 +729,11 @@ static ssize_t _name##_show(struct device *dev,				\
 	u8 index = 0;							\
 	if (ufshcd_is_wb_attrs(QUERY_ATTR_IDN##_uname))			\
 		index = ufshcd_wb_get_query_index(hba);			\
-	pm_runtime_get_sync(hba->dev);					\
+	ret = pm_runtime_get_sync(hba->dev);				\
+	if (ret < 0) {							\
+		pm_runtime_put_noidle(hba->dev);			\
+		return ret;						\
+	}								\
 	ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,	\
 		QUERY_ATTR_IDN##_uname, index, 0, &value);		\
 	pm_runtime_put_sync(hba->dev);					\
@@ -850,7 +872,11 @@ static ssize_t dyn_cap_needed_attribute_show(struct device *dev,
 	u8 lun = ufshcd_scsi_to_upiu_lun(sdev->lun);
 	int ret;
 
-	pm_runtime_get_sync(hba->dev);
+	ret = pm_runtime_get_sync(hba->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(hba->dev);
+		return ret;
+	}
 	ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
 		QUERY_ATTR_IDN_DYN_CAP_NEEDED, lun, 0, &value);
 	pm_runtime_put_sync(hba->dev);
-- 
2.17.1

Re: [PATCH v2 2/3] scsi: ufs: Add handling of the return value of pm_runtime_get_sync()

[Can Guo]

On 2020-12-25 01:20, Bean Huo wrote:
> From: Bean Huo <beanhuo@micron.com>
> 
> The race issue may exist between UFS access in UFS sysfs context and 
> UFS
> shutdown, thus will cause pm_runtime_get_sync() resume failure.

Are you trying to fix the race condition by adding these checks or just
adding these checks in case pm_runtime_get_sync() fails?

Can Guo.

> Add handling of the return value of pm_runtime_get_sync(). Let it 
> return
> in case pm_runtime_get_sync() resume failed.
> 
> Signed-off-by: Bean Huo <beanhuo@micron.com>
> ---
>  drivers/scsi/ufs/ufs-sysfs.c | 38 ++++++++++++++++++++++++++++++------
>  1 file changed, 32 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufs-sysfs.c 
> b/drivers/scsi/ufs/ufs-sysfs.c
> index 0e1438485133..8e5e36e01bee 100644
> --- a/drivers/scsi/ufs/ufs-sysfs.c
> +++ b/drivers/scsi/ufs/ufs-sysfs.c
> @@ -154,12 +154,17 @@ static ssize_t auto_hibern8_show(struct device 
> *dev,
>  				 struct device_attribute *attr, char *buf)
>  {
>  	u32 ahit;
> +	int ret;
>  	struct ufs_hba *hba = dev_get_drvdata(dev);
> 
>  	if (!ufshcd_is_auto_hibern8_supported(hba))
>  		return -EOPNOTSUPP;
> 
> -	pm_runtime_get_sync(hba->dev);
> +	ret = pm_runtime_get_sync(hba->dev);
> +	if (ret < 0) {
> +		pm_runtime_put_noidle(hba->dev);
> +		return ret;
> +	}
>  	ufshcd_hold(hba, false);
>  	ahit = ufshcd_readl(hba, REG_AUTO_HIBERNATE_IDLE_TIMER);
>  	ufshcd_release(hba);
> @@ -225,7 +230,12 @@ static ssize_t ufs_sysfs_read_desc_param(struct
> ufs_hba *hba,
>  	if (param_size > 8)
>  		return -EINVAL;
> 
> -	pm_runtime_get_sync(hba->dev);
> +	ret = pm_runtime_get_sync(hba->dev);
> +	if (ret < 0) {
> +		pm_runtime_put_noidle(hba->dev);
> +		return ret;
> +	}
> +
>  	ret = ufshcd_read_desc_param(hba, desc_id, desc_index,
>  				param_offset, desc_buf, param_size);
>  	pm_runtime_put_sync(hba->dev);
> @@ -594,7 +604,11 @@ static ssize_t _name##_show(struct device 
> *dev,				\
>  	desc_buf = kzalloc(QUERY_DESC_MAX_SIZE, GFP_ATOMIC);		\
>  	if (!desc_buf)                                                  \
>  		return -ENOMEM;                                         \
> -	pm_runtime_get_sync(hba->dev);					\
> +	ret = pm_runtime_get_sync(hba->dev);				\
> +	if (ret < 0) {							\
> +		pm_runtime_put_noidle(hba->dev);			\
> +		return ret;						\
> +	}								\
>  	ret = ufshcd_query_descriptor_retry(hba,			\
>  		UPIU_QUERY_OPCODE_READ_DESC, QUERY_DESC_IDN_DEVICE,	\
>  		0, 0, desc_buf, &desc_len);				\
> @@ -653,7 +667,11 @@ static ssize_t _name##_show(struct device 
> *dev,				\
>  	struct ufs_hba *hba = dev_get_drvdata(dev);			\
>  	if (ufshcd_is_wb_flags(QUERY_FLAG_IDN##_uname))			\
>  		index = ufshcd_wb_get_query_index(hba);			\
> -	pm_runtime_get_sync(hba->dev);					\
> +	ret = pm_runtime_get_sync(hba->dev);				\
> +	if (ret < 0) {							\
> +		pm_runtime_put_noidle(hba->dev);			\
> +		return ret;						\
> +	}								\
>  	ret = ufshcd_query_flag(hba, UPIU_QUERY_OPCODE_READ_FLAG,	\
>  		QUERY_FLAG_IDN##_uname, index, &flag);			\
>  	pm_runtime_put_sync(hba->dev);					\
> @@ -711,7 +729,11 @@ static ssize_t _name##_show(struct device 
> *dev,				\
>  	u8 index = 0;							\
>  	if (ufshcd_is_wb_attrs(QUERY_ATTR_IDN##_uname))			\
>  		index = ufshcd_wb_get_query_index(hba);			\
> -	pm_runtime_get_sync(hba->dev);					\
> +	ret = pm_runtime_get_sync(hba->dev);				\
> +	if (ret < 0) {							\
> +		pm_runtime_put_noidle(hba->dev);			\
> +		return ret;						\
> +	}								\
>  	ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,	\
>  		QUERY_ATTR_IDN##_uname, index, 0, &value);		\
>  	pm_runtime_put_sync(hba->dev);					\
> @@ -850,7 +872,11 @@ static ssize_t
> dyn_cap_needed_attribute_show(struct device *dev,
>  	u8 lun = ufshcd_scsi_to_upiu_lun(sdev->lun);
>  	int ret;
> 
> -	pm_runtime_get_sync(hba->dev);
> +	ret = pm_runtime_get_sync(hba->dev);
> +	if (ret < 0) {
> +		pm_runtime_put_noidle(hba->dev);
> +		return ret;
> +	}
>  	ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
>  		QUERY_ATTR_IDN_DYN_CAP_NEEDED, lun, 0, &value);
>  	pm_runtime_put_sync(hba->dev);

Re: [PATCH v2 2/3] scsi: ufs: Add handling of the return value of pm_runtime_get_sync()

[Bean Huo]

On Mon, 2020-12-28 at 09:50 +0800, Can Guo wrote:
> > The race issue may exist between UFS access in UFS sysfs context
> > and 
> > UFS
> > shutdown, thus will cause pm_runtime_get_sync() resume failure.
> 
> Are you trying to fix the race condition by adding these checks or
> just
> adding these checks in case pm_runtime_get_sync() fails?
> 
> Can Guo.

Can,
thanks for your review. Sorry, I didn't quite get your point.
This patch is just to add checkup in case pm_runtime_get_sync() failed.

what else should be added?

Bean

[PATCH v2 3/3] scsi: ufs: Let resume callback return -EBUSY after ufshcd_shutdown

[Bean Huo]

From: Bean Huo <beanhuo@micron.com>

After ufshcd_shutdown(), both UFS device and UFS LINk are powered off,
return '0' will mislead the upper PM layer since the device has not been
successfully resumed yet. This will let pm_runtime_get_sync() caller
mistakenly believe the device/LINK has been resumed, which leads to
request processing timeout that was en-queued later.

To fix this, let ufshcd_system/runtimie_resume() return -EBUSY in case of
hba->is_powered == false.

Signed-off-by: Bean Huo <beanhuo@micron.com>
---
 drivers/scsi/ufs/ufshcd.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index e221add25a7e..e1bcac51c01f 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -8950,14 +8950,16 @@ int ufshcd_system_resume(struct ufs_hba *hba)
 		return -EINVAL;
 	}
 
-	if (!hba->is_powered || pm_runtime_suspended(hba->dev))
+	if (!hba->is_powered || pm_runtime_suspended(hba->dev)) {
 		/*
 		 * Let the runtime resume take care of resuming
 		 * if runtime suspended.
 		 */
+		ret = -EBUSY;
 		goto out;
-	else
+	} else {
 		ret = ufshcd_resume(hba, UFS_SYSTEM_PM);
+	}
 out:
 	trace_ufshcd_system_resume(dev_name(hba->dev), ret,
 		ktime_to_us(ktime_sub(ktime_get(), start)),
@@ -9026,10 +9028,12 @@ int ufshcd_runtime_resume(struct ufs_hba *hba)
 	if (!hba)
 		return -EINVAL;
 
-	if (!hba->is_powered)
+	if (!hba->is_powered) {
+		ret = -EBUSY;
 		goto out;
-	else
+	} else {
 		ret = ufshcd_resume(hba, UFS_RUNTIME_PM);
+	}
 out:
 	trace_ufshcd_runtime_resume(dev_name(hba->dev), ret,
 		ktime_to_us(ktime_sub(ktime_get(), start)),
-- 
2.17.1

Re: [PATCH v2 3/3] scsi: ufs: Let resume callback return -EBUSY after ufshcd_shutdown

[Bean Huo]

Hi Rafael

Would you please help to review this patch assoociated with PM resume
callback implementation?
 
Original code that ufshcd_system/runtime_resume returns '0' in case
resume failed due to the UFS device and UFS LINk are powered off(hba-
>is_powered == false).

In the patch 2/3 Add handling of the return value of
pm_runtime_get_sync() is to fix race exists between shudown path and
device access through sysfs node.



Thanks,
Bean


On Thu, 2020-12-24 at 18:20 +0100, Bean Huo wrote:
> From: Bean Huo <beanhuo@micron.com>
> 
> After ufshcd_shutdown(), both UFS device and UFS LINk are powered
> off,
> return '0' will mislead the upper PM layer since the device has not
> been
> successfully resumed yet. This will let pm_runtime_get_sync() caller
> mistakenly believe the device/LINK has been resumed, which leads to
> request processing timeout that was en-queued later.
> 
> To fix this, let ufshcd_system/runtimie_resume() return -EBUSY in
> case of
> hba->is_powered == false.
> 
> Signed-off-by: Bean Huo <beanhuo@micron.com>
> ---
>  drivers/scsi/ufs/ufshcd.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index e221add25a7e..e1bcac51c01f 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -8950,14 +8950,16 @@ int ufshcd_system_resume(struct ufs_hba *hba)
>  		return -EINVAL;
>  	}
>  
> -	if (!hba->is_powered || pm_runtime_suspended(hba->dev))
> +	if (!hba->is_powered || pm_runtime_suspended(hba->dev)) {
>  		/*
>  		 * Let the runtime resume take care of resuming
>  		 * if runtime suspended.
>  		 */
> +		ret = -EBUSY;
>  		goto out;
> -	else
> +	} else {
>  		ret = ufshcd_resume(hba, UFS_SYSTEM_PM);
> +	}
>  out:
>  	trace_ufshcd_system_resume(dev_name(hba->dev), ret,
>  		ktime_to_us(ktime_sub(ktime_get(), start)),
> @@ -9026,10 +9028,12 @@ int ufshcd_runtime_resume(struct ufs_hba
> *hba)
>  	if (!hba)
>  		return -EINVAL;
>  
> -	if (!hba->is_powered)
> +	if (!hba->is_powered) {
> +		ret = -EBUSY;
>  		goto out;
> -	else
> +	} else {
>  		ret = ufshcd_resume(hba, UFS_RUNTIME_PM);
> +	}
>  out:
>  	trace_ufshcd_runtime_resume(dev_name(hba->dev), ret,
>  		ktime_to_us(ktime_sub(ktime_get(), start)),

Re: [PATCH v2 3/3] scsi: ufs: Let resume callback return -EBUSY after ufshcd_shutdown

[Can Guo]

On 2020-12-25 01:20, Bean Huo wrote:
> From: Bean Huo <beanhuo@micron.com>
> 
> After ufshcd_shutdown(), both UFS device and UFS LINk are powered off,
> return '0' will mislead the upper PM layer since the device has not 
> been
> successfully resumed yet. This will let pm_runtime_get_sync() caller
> mistakenly believe the device/LINK has been resumed, which leads to
> request processing timeout that was en-queued later.
> 
> To fix this, let ufshcd_system/runtimie_resume() return -EBUSY in case 
> of
> hba->is_powered == false.

This change won't work as you expect...

During/after shutdown, for UFS's case only,
pm_runtime_get_sync(hba->dev) will most likely return 0,
because it is already RUNTIME_ACTIVE, pm_runtime_get_sync()
will directly return 0... meaning your change won't even be
exercised.

Check Stanley's change -
https://lore.kernel.org/patchwork/patch/1341389/

Can Guo.

> 
> Signed-off-by: Bean Huo <beanhuo@micron.com>
> ---
>  drivers/scsi/ufs/ufshcd.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index e221add25a7e..e1bcac51c01f 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -8950,14 +8950,16 @@ int ufshcd_system_resume(struct ufs_hba *hba)
>  		return -EINVAL;
>  	}
> 
> -	if (!hba->is_powered || pm_runtime_suspended(hba->dev))
> +	if (!hba->is_powered || pm_runtime_suspended(hba->dev)) {
>  		/*
>  		 * Let the runtime resume take care of resuming
>  		 * if runtime suspended.
>  		 */
> +		ret = -EBUSY;
>  		goto out;
> -	else
> +	} else {
>  		ret = ufshcd_resume(hba, UFS_SYSTEM_PM);
> +	}
>  out:
>  	trace_ufshcd_system_resume(dev_name(hba->dev), ret,
>  		ktime_to_us(ktime_sub(ktime_get(), start)),
> @@ -9026,10 +9028,12 @@ int ufshcd_runtime_resume(struct ufs_hba *hba)
>  	if (!hba)
>  		return -EINVAL;
> 
> -	if (!hba->is_powered)
> +	if (!hba->is_powered) {
> +		ret = -EBUSY;
>  		goto out;
> -	else
> +	} else {
>  		ret = ufshcd_resume(hba, UFS_RUNTIME_PM);
> +	}
>  out:
>  	trace_ufshcd_runtime_resume(dev_name(hba->dev), ret,
>  		ktime_to_us(ktime_sub(ktime_get(), start)),