[PATCH V2 0/4] scsi: ufs-debugfs: Add UFS Exception Event reporting

[PATCH V2 0/4] scsi: ufs-debugfs: Add UFS Exception Event reporting

[Adrian Hunter]

Hi

Here are V2 patches to add a tracepoint for UFS Exception Events and to
allow users to enable specific exception events without affecting the
driver's use of exception events.


Changes in V2:

    scsi: ufs: Add exception event tracepoint
	Change status field from "exception event status" to "status"

    scsi: ufs: Add exception event definitions
	Add Reviewed-by: Bean Huo


Adrian Hunter (4):
      scsi: ufs: Add exception event tracepoint
      scsi: ufs: Add exception event definitions
      scsi: ufs-debugfs: Add user-defined exception_event_mask
      scsi: ufs-debugfs: Add user-defined exception event rate limiting

 drivers/scsi/ufs/ufs-debugfs.c | 90 ++++++++++++++++++++++++++++++++++++++++++
 drivers/scsi/ufs/ufs-debugfs.h |  2 +
 drivers/scsi/ufs/ufs.h         | 10 ++++-
 drivers/scsi/ufs/ufshcd.c      | 87 +++++++++++++++++++++++++---------------
 drivers/scsi/ufs/ufshcd.h      | 26 +++++++++++-
 include/trace/events/ufs.h     | 21 ++++++++++
 6 files changed, 201 insertions(+), 35 deletions(-)


Regards
Adrian

[PATCH V2 1/4] scsi: ufs: Add exception event tracepoint

[Adrian Hunter]

Currently, exception event status can be read from wExceptionEventStatus
attribute (sysfs file attributes/exception_event_status under the UFS host
controller device directory). Polling that attribute to track UFS exception
events is impractical, so add a tracepoint to track exception events for
testing and debugging purposes.

Note, by the time the exception event status is read, the exception event
may have cleared, so the value can be zero - see example below.

Note also, only enabled exception events can be reported. A subsequent
patch adds the ability for users to enable selected exception events via
debugfs.

Example with driver instrumented to enable all exception events:

  # echo 1 > /sys/kernel/debug/tracing/events/ufs/ufshcd_exception_event/enable

  ... do some I/O ...

  # cat /sys/kernel/debug/tracing/trace
  # tracer: nop
  #
  # entries-in-buffer/entries-written: 3/3   #P:5
  #
  #                                _-----=> irqs-off
  #                               / _----=> need-resched
  #                              | / _---=> hardirq/softirq
  #                              || / _--=> preempt-depth
  #                              ||| /     delay
  #           TASK-PID     CPU#  ||||   TIMESTAMP  FUNCTION
  #              | |         |   ||||      |         |
       kworker/2:2-173     [002] ....   731.486419: ufshcd_exception_event: 0000:00:12.5: status 0x0
       kworker/2:2-173     [002] ....   732.608918: ufshcd_exception_event: 0000:00:12.5: status 0x4
       kworker/2:2-173     [002] ....   732.609312: ufshcd_exception_event: 0000:00:12.5: status 0x4

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/scsi/ufs/ufshcd.c  |  2 ++
 include/trace/events/ufs.h | 21 +++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 721f55db181f..d6fdce655388 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5616,6 +5616,8 @@ static void ufshcd_exception_event_handler(struct work_struct *work)
 		goto out;
 	}
 
+	trace_ufshcd_exception_event(dev_name(hba->dev), status);
+
 	status &= hba->ee_ctrl_mask;
 
 	if (status & MASK_EE_URGENT_BKOPS)
diff --git a/include/trace/events/ufs.h b/include/trace/events/ufs.h
index e151477d645c..1cb6f1afba0e 100644
--- a/include/trace/events/ufs.h
+++ b/include/trace/events/ufs.h
@@ -349,6 +349,27 @@ TRACE_EVENT(ufshcd_upiu,
 	)
 );
 
+TRACE_EVENT(ufshcd_exception_event,
+
+	TP_PROTO(const char *dev_name, u16 status),
+
+	TP_ARGS(dev_name, status),
+
+	TP_STRUCT__entry(
+		__string(dev_name, dev_name)
+		__field(u16, status)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev_name, dev_name);
+		__entry->status = status;
+	),
+
+	TP_printk("%s: status 0x%x",
+		__get_str(dev_name), __entry->status
+	)
+);
+
 #endif /* if !defined(_TRACE_UFS_H) || defined(TRACE_HEADER_MULTI_READ) */
 
 /* This part must be outside protection */
-- 
2.17.1

RE: [PATCH V2 1/4] scsi: ufs: Add exception event tracepoint

[Avri Altman]

> 
> Currently, exception event status can be read from wExceptionEventStatus
> attribute (sysfs file attributes/exception_event_status under the UFS host
> controller device directory). Polling that attribute to track UFS exception
> events is impractical, so add a tracepoint to track exception events for
> testing and debugging purposes.
> 
> Note, by the time the exception event status is read, the exception event
> may have cleared, so the value can be zero - see example below.
> 
> Note also, only enabled exception events can be reported. A subsequent
> patch adds the ability for users to enable selected exception events via
> debugfs.
> 
> Example with driver instrumented to enable all exception events:
> 
>   # echo 1 >
> /sys/kernel/debug/tracing/events/ufs/ufshcd_exception_event/enable
> 
>   ... do some I/O ...
> 
>   # cat /sys/kernel/debug/tracing/trace
>   # tracer: nop
>   #
>   # entries-in-buffer/entries-written: 3/3   #P:5
>   #
>   #                                _-----=> irqs-off
>   #                               / _----=> need-resched
>   #                              | / _---=> hardirq/softirq
>   #                              || / _--=> preempt-depth
>   #                              ||| /     delay
>   #           TASK-PID     CPU#  ||||   TIMESTAMP  FUNCTION
>   #              | |         |   ||||      |         |
>        kworker/2:2-173     [002] ....   731.486419: ufshcd_exception_event:
> 0000:00:12.5: status 0x0
>        kworker/2:2-173     [002] ....   732.608918: ufshcd_exception_event:
> 0000:00:12.5: status 0x4
>        kworker/2:2-173     [002] ....   732.609312: ufshcd_exception_event:
> 0000:00:12.5: status 0x4
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>

Re: [PATCH V2 1/4] scsi: ufs: Add exception event tracepoint

[Bean Huo]

On Tue, 2021-02-09 at 08:24 +0200, Adrian Hunter wrote:
>   # cat /sys/kernel/debug/tracing/trace
>   # tracer: nop
>   #
>   # entries-in-buffer/entries-written: 3/3   #P:5
>   #
>   #                                _-----=> irqs-off
>   #                               / _----=> need-resched
>   #                              | / _---=> hardirq/softirq
>   #                              || / _--=> preempt-depth
>   #                              ||| /     delay
>   #           TASK-PID     CPU#  ||||   TIMESTAMP  FUNCTION
>   #              | |         |   ||||      |         |
>        kworker/2:2-173     [002] ....   731.486419:
> ufshcd_exception_event: 0000:00:12.5: status 0x0
>        kworker/2:2-173     [002] ....   732.608918:
> ufshcd_exception_event: 0000:00:12.5: status 0x4
>        kworker/2:2-173     [002] ....   732.609312:
> ufshcd_exception_event: 0000:00:12.5: status 0x4
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>

[PATCH V2 2/4] scsi: ufs: Add exception event definitions

[Adrian Hunter]

For readability and completeness, add exception event definitions.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
---
 drivers/scsi/ufs/ufs.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
index bf1897a72532..cb80b9670bfe 100644
--- a/drivers/scsi/ufs/ufs.h
+++ b/drivers/scsi/ufs/ufs.h
@@ -348,8 +348,14 @@ enum power_desc_param_offset {
 
 /* Exception event mask values */
 enum {
-	MASK_EE_STATUS		= 0xFFFF,
-	MASK_EE_URGENT_BKOPS	= (1 << 2),
+	MASK_EE_STATUS			= 0xFFFF,
+	MASK_EE_DYNCAP_EVENT		= BIT(0),
+	MASK_EE_SYSPOOL_EVENT		= BIT(1),
+	MASK_EE_URGENT_BKOPS		= BIT(2),
+	MASK_EE_TOO_HIGH_TEMP		= BIT(3),
+	MASK_EE_TOO_LOW_TEMP		= BIT(4),
+	MASK_EE_WRITEBOOSTER_EVENT	= BIT(5),
+	MASK_EE_PERFORMANCE_THROTTLING	= BIT(6),
 };
 
 /* Background operation status */
-- 
2.17.1

[PATCH V2 3/4] scsi: ufs-debugfs: Add user-defined exception_event_mask

[Adrian Hunter]

Allow users to enable specific exception events via debugfs.

The bits enabled by the driver ee_drv_ctrl are separated from the bits
enabled by the user ee_usr_ctrl. The control mask ee_mask_ctrl is the
logical-or of those two. A mutex is needed to ensure that the masks match
what was written to the device.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/scsi/ufs/ufs-debugfs.c | 46 ++++++++++++++++++
 drivers/scsi/ufs/ufshcd.c      | 86 +++++++++++++++++++++-------------
 drivers/scsi/ufs/ufshcd.h      | 22 ++++++++-
 3 files changed, 120 insertions(+), 34 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-debugfs.c b/drivers/scsi/ufs/ufs-debugfs.c
index dee98dc72d29..59729073b569 100644
--- a/drivers/scsi/ufs/ufs-debugfs.c
+++ b/drivers/scsi/ufs/ufs-debugfs.c
@@ -44,10 +44,56 @@ static int ufs_debugfs_stats_show(struct seq_file *s, void *data)
 }
 DEFINE_SHOW_ATTRIBUTE(ufs_debugfs_stats);
 
+static int ee_usr_mask_get(void *data, u64 *val)
+{
+	struct ufs_hba *hba = data;
+
+	*val = hba->ee_usr_mask;
+	return 0;
+}
+
+static int ufs_debugfs_get_user_access(struct ufs_hba *hba)
+__acquires(&hba->host_sem)
+{
+	down(&hba->host_sem);
+	if (!ufshcd_is_user_access_allowed(hba)) {
+		up(&hba->host_sem);
+		return -EBUSY;
+	}
+	pm_runtime_get_sync(hba->dev);
+	return 0;
+}
+
+static void ufs_debugfs_put_user_access(struct ufs_hba *hba)
+__releases(&hba->host_sem)
+{
+	pm_runtime_put_sync(hba->dev);
+	up(&hba->host_sem);
+}
+
+static int ee_usr_mask_set(void *data, u64 val)
+{
+	struct ufs_hba *hba = data;
+	int err;
+
+	if (val & ~(u64)MASK_EE_STATUS)
+		return -EINVAL;
+	err = ufs_debugfs_get_user_access(hba);
+	if (err)
+		return err;
+	err = ufshcd_update_ee_usr_mask(hba, val, MASK_EE_STATUS);
+	ufs_debugfs_put_user_access(hba);
+	return err;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(ee_usr_mask_fops, ee_usr_mask_get, ee_usr_mask_set, "%#llx\n");
+
 void ufs_debugfs_hba_init(struct ufs_hba *hba)
 {
 	hba->debugfs_root = debugfs_create_dir(dev_name(hba->dev), ufs_debugfs_root);
 	debugfs_create_file("stats", 0400, hba->debugfs_root, hba, &ufs_debugfs_stats_fops);
+	debugfs_create_file("exception_event_mask", 0600, hba->debugfs_root,
+			    hba, &ee_usr_mask_fops);
 }
 
 void ufs_debugfs_hba_exit(struct ufs_hba *hba)
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index d6fdce655388..065a662e7886 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5160,6 +5160,46 @@ static irqreturn_t ufshcd_transfer_req_compl(struct ufs_hba *hba)
 	}
 }
 
+static int __ufshcd_write_ee_control(struct ufs_hba *hba, u32 ee_ctrl_mask)
+{
+	return ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
+				       QUERY_ATTR_IDN_EE_CONTROL, 0, 0,
+				       &ee_ctrl_mask);
+}
+
+static int ufshcd_write_ee_control(struct ufs_hba *hba)
+{
+	int err;
+
+	mutex_lock(&hba->ee_ctrl_mutex);
+	err = __ufshcd_write_ee_control(hba, hba->ee_ctrl_mask);
+	mutex_unlock(&hba->ee_ctrl_mutex);
+	if (err)
+		dev_err(hba->dev, "%s: failed to write ee control %d\n",
+			__func__, err);
+	return err;
+}
+
+int ufshcd_update_ee_control(struct ufs_hba *hba, u16 *mask, u16 *other_mask,
+			     u16 set, u16 clr)
+{
+	u16 new_mask, ee_ctrl_mask;
+	int err = 0;
+
+	mutex_lock(&hba->ee_ctrl_mutex);
+	new_mask = (*mask & ~clr) | set;
+	ee_ctrl_mask = new_mask | *other_mask;
+	if (ee_ctrl_mask != hba->ee_ctrl_mask)
+		err = __ufshcd_write_ee_control(hba, ee_ctrl_mask);
+	/* Still need to update 'mask' even if 'ee_ctrl_mask' was unchanged */
+	if (!err) {
+		hba->ee_ctrl_mask = ee_ctrl_mask;
+		*mask = new_mask;
+	}
+	mutex_unlock(&hba->ee_ctrl_mutex);
+	return err;
+}
+
 /**
  * ufshcd_disable_ee - disable exception event
  * @hba: per-adapter instance
@@ -5170,22 +5210,9 @@ static irqreturn_t ufshcd_transfer_req_compl(struct ufs_hba *hba)
  *
  * Returns zero on success, non-zero error value on failure.
  */
-static int ufshcd_disable_ee(struct ufs_hba *hba, u16 mask)
+static inline int ufshcd_disable_ee(struct ufs_hba *hba, u16 mask)
 {
-	int err = 0;
-	u32 val;
-
-	if (!(hba->ee_ctrl_mask & mask))
-		goto out;
-
-	val = hba->ee_ctrl_mask & ~mask;
-	val &= MASK_EE_STATUS;
-	err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
-			QUERY_ATTR_IDN_EE_CONTROL, 0, 0, &val);
-	if (!err)
-		hba->ee_ctrl_mask &= ~mask;
-out:
-	return err;
+	return ufshcd_update_ee_drv_mask(hba, 0, mask);
 }
 
 /**
@@ -5198,22 +5225,9 @@ static int ufshcd_disable_ee(struct ufs_hba *hba, u16 mask)
  *
  * Returns zero on success, non-zero error value on failure.
  */
-static int ufshcd_enable_ee(struct ufs_hba *hba, u16 mask)
+static inline int ufshcd_enable_ee(struct ufs_hba *hba, u16 mask)
 {
-	int err = 0;
-	u32 val;
-
-	if (hba->ee_ctrl_mask & mask)
-		goto out;
-
-	val = hba->ee_ctrl_mask | mask;
-	val &= MASK_EE_STATUS;
-	err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
-			QUERY_ATTR_IDN_EE_CONTROL, 0, 0, &val);
-	if (!err)
-		hba->ee_ctrl_mask |= mask;
-out:
-	return err;
+	return ufshcd_update_ee_drv_mask(hba, mask, 0);
 }
 
 /**
@@ -5618,9 +5632,7 @@ static void ufshcd_exception_event_handler(struct work_struct *work)
 
 	trace_ufshcd_exception_event(dev_name(hba->dev), status);
 
-	status &= hba->ee_ctrl_mask;
-
-	if (status & MASK_EE_URGENT_BKOPS)
+	if (status & hba->ee_drv_mask & MASK_EE_URGENT_BKOPS)
 		ufshcd_bkops_exception_event_handler(hba);
 
 out:
@@ -7921,6 +7933,8 @@ static int ufshcd_probe_hba(struct ufs_hba *hba, bool async)
 	ufshcd_set_active_icc_lvl(hba);
 
 	ufshcd_wb_config(hba);
+	if (hba->ee_usr_mask)
+		ufshcd_write_ee_control(hba);
 	/* Enable Auto-Hibernate if configured */
 	ufshcd_auto_hibern8_enable(hba);
 
@@ -8918,6 +8932,9 @@ static int ufshcd_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 		 */
 		ufshcd_urgent_bkops(hba);
 
+	if (hba->ee_usr_mask)
+		ufshcd_write_ee_control(hba);
+
 	hba->clk_gating.is_suspended = false;
 
 	if (ufshcd_is_clkscaling_supported(hba))
@@ -9355,6 +9372,9 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 	/* Initialize mutex for device management commands */
 	mutex_init(&hba->dev_cmd.lock);
 
+	/* Initialize mutex for exception event control */
+	mutex_init(&hba->ee_ctrl_mutex);
+
 	init_rwsem(&hba->clk_scaling_lock);
 
 	ufshcd_init_clk_gating(hba);
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index ee61f821f75d..9b7413f35def 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -773,7 +773,10 @@ struct ufs_hba {
 	u32 ufshcd_state;
 	u32 eh_flags;
 	u32 intr_mask;
-	u16 ee_ctrl_mask;
+	u16 ee_ctrl_mask; /* Exception event mask */
+	u16 ee_drv_mask;  /* Exception event mask for driver */
+	u16 ee_usr_mask;  /* Exception event mask for user (via debugfs) */
+	struct mutex ee_ctrl_mutex;
 	bool is_powered;
 	bool shutting_down;
 	struct semaphore host_sem;
@@ -1285,4 +1288,21 @@ static inline u8 ufshcd_scsi_to_upiu_lun(unsigned int scsi_lun)
 int ufshcd_dump_regs(struct ufs_hba *hba, size_t offset, size_t len,
 		     const char *prefix);
 
+int ufshcd_update_ee_control(struct ufs_hba *hba, u16 *mask, u16 *other_mask,
+			     u16 set, u16 clr);
+
+static inline int ufshcd_update_ee_drv_mask(struct ufs_hba *hba,
+					    u16 set, u16 clr)
+{
+	return ufshcd_update_ee_control(hba, &hba->ee_drv_mask,
+					&hba->ee_usr_mask, set, clr);
+}
+
+static inline int ufshcd_update_ee_usr_mask(struct ufs_hba *hba,
+					    u16 set, u16 clr)
+{
+	return ufshcd_update_ee_control(hba, &hba->ee_usr_mask,
+					&hba->ee_drv_mask, set, clr);
+}
+
 #endif /* End of Header */
-- 
2.17.1

Re: [PATCH V2 3/4] scsi: ufs-debugfs: Add user-defined exception_event_mask

[Bean Huo]

On Tue, 2021-02-09 at 08:24 +0200, Adrian Hunter wrote:
> Allow users to enable specific exception events via debugfs.
> 
> The bits enabled by the driver ee_drv_ctrl are separated from the
> bits
> enabled by the user ee_usr_ctrl. The control mask ee_mask_ctrl is the
> logical-or of those two. A mutex is needed to ensure that the masks
> match
> what was written to the device.
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Hi Adrian,
I tested this series patch on my platform, and you can add:

Acked-by: Bean Huo <beanhuo@micron.com>


Bean

[PATCH V2 4/4] scsi: ufs-debugfs: Add user-defined exception event rate limiting

[Adrian Hunter]

An enabled user-specified exception event that does not clear quickly will
repeatedly cause the handler to run. That could unduly disturb the driver
behaviour being tested or debugged. To prevent that add debugfs file
exception_event_rate_limit_ms. When a exception event happens, it is
disabled, and then after a period of time (default 20ms) the exception
event is enabled again.

Note that if the driver also has that exception event enabled, it will not
be disabled.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/scsi/ufs/ufs-debugfs.c | 44 ++++++++++++++++++++++++++++++++++
 drivers/scsi/ufs/ufs-debugfs.h |  2 ++
 drivers/scsi/ufs/ufshcd.c      |  5 ++--
 drivers/scsi/ufs/ufshcd.h      |  4 ++++
 4 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-debugfs.c b/drivers/scsi/ufs/ufs-debugfs.c
index 59729073b569..ced9ef4d7c78 100644
--- a/drivers/scsi/ufs/ufs-debugfs.c
+++ b/drivers/scsi/ufs/ufs-debugfs.c
@@ -88,15 +88,59 @@ static int ee_usr_mask_set(void *data, u64 val)
 
 DEFINE_DEBUGFS_ATTRIBUTE(ee_usr_mask_fops, ee_usr_mask_get, ee_usr_mask_set, "%#llx\n");
 
+void ufs_debugfs_exception_event(struct ufs_hba *hba, u16 status)
+{
+	bool chgd = false;
+	u16 ee_ctrl_mask;
+	int err = 0;
+
+	if (!hba->debugfs_ee_rate_limit_ms || !status)
+		return;
+
+	mutex_lock(&hba->ee_ctrl_mutex);
+	ee_ctrl_mask = hba->ee_drv_mask | (hba->ee_usr_mask & ~status);
+	chgd = ee_ctrl_mask != hba->ee_ctrl_mask;
+	if (chgd) {
+		err = __ufshcd_write_ee_control(hba, ee_ctrl_mask);
+		if (err)
+			dev_err(hba->dev, "%s: failed to write ee control %d\n",
+				__func__, err);
+	}
+	mutex_unlock(&hba->ee_ctrl_mutex);
+
+	if (chgd && !err) {
+		unsigned long delay = msecs_to_jiffies(hba->debugfs_ee_rate_limit_ms);
+
+		queue_delayed_work(system_freezable_wq, &hba->debugfs_ee_work, delay);
+	}
+}
+
+static void ufs_debugfs_restart_ee(struct work_struct *work)
+{
+	struct ufs_hba *hba = container_of(work, struct ufs_hba, debugfs_ee_work.work);
+
+	if (!hba->ee_usr_mask || pm_runtime_suspended(hba->dev) ||
+	    ufs_debugfs_get_user_access(hba))
+		return;
+	ufshcd_write_ee_control(hba);
+	ufs_debugfs_put_user_access(hba);
+}
+
 void ufs_debugfs_hba_init(struct ufs_hba *hba)
 {
+	/* Set default exception event rate limit period to 20ms */
+	hba->debugfs_ee_rate_limit_ms = 20;
+	INIT_DELAYED_WORK(&hba->debugfs_ee_work, ufs_debugfs_restart_ee);
 	hba->debugfs_root = debugfs_create_dir(dev_name(hba->dev), ufs_debugfs_root);
 	debugfs_create_file("stats", 0400, hba->debugfs_root, hba, &ufs_debugfs_stats_fops);
 	debugfs_create_file("exception_event_mask", 0600, hba->debugfs_root,
 			    hba, &ee_usr_mask_fops);
+	debugfs_create_u32("exception_event_rate_limit_ms", 0600, hba->debugfs_root,
+			   &hba->debugfs_ee_rate_limit_ms);
 }
 
 void ufs_debugfs_hba_exit(struct ufs_hba *hba)
 {
 	debugfs_remove_recursive(hba->debugfs_root);
+	cancel_delayed_work_sync(&hba->debugfs_ee_work);
 }
diff --git a/drivers/scsi/ufs/ufs-debugfs.h b/drivers/scsi/ufs/ufs-debugfs.h
index f35b39c4b4f5..3ca29d30460a 100644
--- a/drivers/scsi/ufs/ufs-debugfs.h
+++ b/drivers/scsi/ufs/ufs-debugfs.h
@@ -12,11 +12,13 @@ void __init ufs_debugfs_init(void);
 void __exit ufs_debugfs_exit(void);
 void ufs_debugfs_hba_init(struct ufs_hba *hba);
 void ufs_debugfs_hba_exit(struct ufs_hba *hba);
+void ufs_debugfs_exception_event(struct ufs_hba *hba, u16 status);
 #else
 static inline void ufs_debugfs_init(void) {}
 static inline void ufs_debugfs_exit(void) {}
 static inline void ufs_debugfs_hba_init(struct ufs_hba *hba) {}
 static inline void ufs_debugfs_hba_exit(struct ufs_hba *hba) {}
+static inline void ufs_debugfs_exception_event(struct ufs_hba *hba, u16 status) {}
 #endif
 
 #endif
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 065a662e7886..42d9a96a5721 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5160,14 +5160,14 @@ static irqreturn_t ufshcd_transfer_req_compl(struct ufs_hba *hba)
 	}
 }
 
-static int __ufshcd_write_ee_control(struct ufs_hba *hba, u32 ee_ctrl_mask)
+int __ufshcd_write_ee_control(struct ufs_hba *hba, u32 ee_ctrl_mask)
 {
 	return ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
 				       QUERY_ATTR_IDN_EE_CONTROL, 0, 0,
 				       &ee_ctrl_mask);
 }
 
-static int ufshcd_write_ee_control(struct ufs_hba *hba)
+int ufshcd_write_ee_control(struct ufs_hba *hba)
 {
 	int err;
 
@@ -5635,6 +5635,7 @@ static void ufshcd_exception_event_handler(struct work_struct *work)
 	if (status & hba->ee_drv_mask & MASK_EE_URGENT_BKOPS)
 		ufshcd_bkops_exception_event_handler(hba);
 
+	ufs_debugfs_exception_event(hba, status);
 out:
 	ufshcd_scsi_unblock_requests(hba);
 	/*
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 9b7413f35def..8a52b63ad4e6 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -843,6 +843,8 @@ struct ufs_hba {
 #endif
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *debugfs_root;
+	struct delayed_work debugfs_ee_work;
+	u32 debugfs_ee_rate_limit_ms;
 #endif
 };
 
@@ -1288,6 +1290,8 @@ static inline u8 ufshcd_scsi_to_upiu_lun(unsigned int scsi_lun)
 int ufshcd_dump_regs(struct ufs_hba *hba, size_t offset, size_t len,
 		     const char *prefix);
 
+int __ufshcd_write_ee_control(struct ufs_hba *hba, u32 ee_ctrl_mask);
+int ufshcd_write_ee_control(struct ufs_hba *hba);
 int ufshcd_update_ee_control(struct ufs_hba *hba, u16 *mask, u16 *other_mask,
 			     u16 set, u16 clr);
 
-- 
2.17.1

Re: [PATCH V2 4/4] scsi: ufs-debugfs: Add user-defined exception event rate limiting

[Bean Huo]

On Tue, 2021-02-09 at 08:24 +0200, Adrian Hunter wrote:
> An enabled user-specified exception event that does not clear quickly
> will
> repeatedly cause the handler to run. That could unduly disturb the
> driver
> behaviour being tested or debugged. To prevent that add debugfs file
> exception_event_rate_limit_ms. When a exception event happens, it is
> disabled, and then after a period of time (default 20ms) the
> exception
> event is enabled again.
> 
> Note that if the driver also has that exception event enabled, it
> will not
> be disabled.
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Bean Huo <beanhuo@micron.com>

Re: [PATCH V2 0/4] scsi: ufs-debugfs: Add UFS Exception Event reporting

[Martin K. Petersen]

On Tue, 9 Feb 2021 08:24:33 +0200, Adrian Hunter wrote:

> Here are V2 patches to add a tracepoint for UFS Exception Events and to
> allow users to enable specific exception events without affecting the
> driver's use of exception events.
> 
> 
> Changes in V2:
> 
> [...]

Applied to 5.13/scsi-queue, thanks!

[1/4] scsi: ufs: Add exception event tracepoint
      https://git.kernel.org/mkp/scsi/c/26b01633fac8
[2/4] scsi: ufs: Add exception event definitions
      https://git.kernel.org/mkp/scsi/c/8fd31fc2b84f
[3/4] scsi: ufs-debugfs: Add user-defined exception_event_mask
      https://git.kernel.org/mkp/scsi/c/e1c8b528dd23
[4/4] scsi: ufs-debugfs: Add user-defined exception event rate limiting
      https://git.kernel.org/mkp/scsi/c/c3f04083d653

-- 
Martin K. Petersen	Oracle Linux Engineering