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acpi: indicate to platform when hot remove returns busy

PATCH Superseded Lee, Chun-Yi 3 participants 3 messages Jun 9, 2017 – Jun 10, 2017 ACPI

v2 of 4 Superseded Latest is v4 →

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Lee, Chun-Yi

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#0 lore raw

PATCH v2 1/1 acpi: indicate to platform when hot remove returns busy

In hotplug logic, it always indicates non-specific failure to platform through _OST when handing acpi hot-remove event failed. Then platform terminates the hot-remove process but it can not identify the reason.

Base on current hot-remove code, there have two situations that it returns busy:
- OSPM try to offline an individual device, but the device offline function returns busy.
- When the ejection event is applied to an "not offlined yet" container. OSPM send kobject change event to userspace and returns busy.

Both of them will returns -EBUSY to acpi device hotplug function then hotplug function indicates non-specific failure to platform just like any other error, e.g. -ENODEV or -EIO.

The benefit to platform for identifying the OS busy state is that platform can be applied different approach to handle the busy but not just terminate the hot-remove process by unknown reason. For example, platform can wait for a while then triggers hot-remove again.

This RFC patch adds one more parameter to the handler function of acpi generic hotplug event to give the function a chance to propose the return code of _OST. In this case, it sets ost return code to ACPI_OST_SC_DEVICE_BUSY when the acpi hot remove function returns -EBUSY.

v2:
Do not overwrite ost code in acpi_generic_hotplug_event(). Move the "error code to ost code" logic to a help function.

Cc "Rafael J. Wysocki" <[email protected]>
Cc Len Brown <[email protected]>
Cc Andy Shevchenko <[email protected]>
Signed-off-by "Lee, Chun-Yi" <[email protected]>
---
 drivers/acpi/scan.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)
drivers/acpi/scan.c +15 -6
index 2433569..e407eed 100644
@@ -394,6 +394,20 @@ static int acpi_generic_hotplug_event(struct acpi_device *adev, u32 type)
 	return -EINVAL;
 }
 
+static int acpi_ost_status_code(u32 src, int error)
+{
+	switch (src) {
+	case ACPI_NOTIFY_EJECT_REQUEST:
+	case ACPI_OST_EC_OSPM_EJECT:
+		if (error == -EPERM)
+			return ACPI_OST_SC_EJECT_NOT_SUPPORTED;
+		else if (error == -EBUSY)
+			return ACPI_OST_SC_DEVICE_BUSY;
+		break;
+	}
+	return error ? ACPI_OST_SC_NON_SPECIFIC_FAILURE : ACPI_OST_SC_SUCCESS;
+}
+
 void acpi_device_hotplug(struct acpi_device *adev, u32 src)
 {
 	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;

@@ -414,10 +428,6 @@ void acpi_device_hotplug(struct acpi_device *adev, u32 src)
 		error = dock_notify(adev, src);
 	} else if (adev->flags.hotplug_notify) {
 		error = acpi_generic_hotplug_event(adev, src);
-		if (error == -EPERM) {
-			ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED;
-			goto err_out;
-		}
 	} else {
 		int (*notify)(struct acpi_device *, u32);
 

@@ -433,9 +443,8 @@ void acpi_device_hotplug(struct acpi_device *adev, u32 src)
 		else
 			goto out;
 	}
-	if (!error)
-		ost_code = ACPI_OST_SC_SUCCESS;
 
+	ost_code = acpi_ost_status_code(src, error);
  err_out:
 	acpi_evaluate_ost(adev->handle, src, ost_code, NULL);
Signature · 1 line
2.10.2
#1 lore raw
Quoted 22 lines · Chun-Yi

In hotplug logic, it always indicates non-specific failure to platform through _OST when handing acpi hot-remove event failed. Then platform terminates the hot-remove process but it can not identify the reason.

Base on current hot-remove code, there have two situations that it returns busy:
- OSPM try to offline an individual device, but the device offline function returns busy.
- When the ejection event is applied to an "not offlined yet" container. OSPM send kobject change event to userspace and returns busy.

Both of them will returns -EBUSY to acpi device hotplug function then hotplug function indicates non-specific failure to platform just like any other error, e.g. -ENODEV or -EIO.

The benefit to platform for identifying the OS busy state is that platform can be applied different approach to handle the busy but not just terminate the hot-remove process by unknown reason. For example, platform can wait for a while then triggers hot-remove again.

Quoted 5 lines

This RFC patch adds one more parameter to the handler function of acpi generic hotplug event to give the function a chance to propose the return code of _OST. In this case, it sets ost return code to ACPI_OST_SC_DEVICE_BUSY when the acpi hot remove function returns -EBUSY.

Below looks better for my taste.
See also comments.

drivers/acpi/scan.c static int acpi_generic_hotplug_event(struct acpi_device *adev, u32 type) · line 404

Quoted 9 lines
drivers/acpi/scan.c +8 -0
+static int acpi_ost_status_code(u32 src, int error)
+{
+       switch (src) {
+       case ACPI_NOTIFY_EJECT_REQUEST:
+       case ACPI_OST_EC_OSPM_EJECT:
 
+               if (error == -EPERM)
+                       return ACPI_OST_SC_EJECT_NOT_SUPPORTED;
+               else if (error == -EBUSY)

Redundant else...

Quoted 1 line

+ return ACPI_OST_SC_DEVICE_BUSY;

Perhaps switch case here as well?
switch (error) {
case -EPERM;
return X;
case -EBUSY:
return Y;
}

drivers/acpi/scan.c static int acpi_generic_hotplug_event(struct acpi_device *adev, u32 type)

Quoted 8 lines
drivers/acpi/scan.c +5 -0
+               break;
+       }
+       return error ? ACPI_OST_SC_NON_SPECIFIC_FAILURE : ACPI_OST_SC_SUCCESS;
+}
 
 
+       ost_code = acpi_ost_status_code(src, error);
  err_out:

I guess you need to swap those lines.

Quoted 1 line
        acpi_evaluate_ost(adev->handle, src, ost_code, NULL);
Signature · 2 lines
With Best Regards,
Andy Shevchenko
#2 lore raw
Quoted 23 lines · Andy Shevchenko
Quoted 22 lines · Chun-Yi

In hotplug logic, it always indicates non-specific failure to platform through _OST when handing acpi hot-remove event failed. Then platform terminates the hot-remove process but it can not identify the reason.

Base on current hot-remove code, there have two situations that it returns busy:
- OSPM try to offline an individual device, but the device offline function returns busy.
- When the ejection event is applied to an "not offlined yet" container. OSPM send kobject change event to userspace and returns busy.

Both of them will returns -EBUSY to acpi device hotplug function then hotplug function indicates non-specific failure to platform just like any other error, e.g. -ENODEV or -EIO.

The benefit to platform for identifying the OS busy state is that platform can be applied different approach to handle the busy but not just terminate the hot-remove process by unknown reason. For example, platform can wait for a while then triggers hot-remove again.

Quoted 9 lines
Quoted 5 lines

This RFC patch adds one more parameter to the handler function of acpi generic hotplug event to give the function a chance to propose the return code of _OST. In this case, it sets ost return code to ACPI_OST_SC_DEVICE_BUSY when the acpi hot remove function returns -EBUSY.

Below looks better for my taste.
See also comments.

Still thanks for your review.

Quoted 6 lines
Quoted 5 lines
drivers/acpi/scan.c +5 -0
+static int acpi_ost_status_code(u32 src, int error)
+{
+       switch (src) {
+       case ACPI_NOTIFY_EJECT_REQUEST:
+       case ACPI_OST_EC_OSPM_EJECT:
Quoted 6 lines

drivers/acpi/scan.c static int acpi_generic_hotplug_event(struct acpi_device *adev, u32 type) · line 404

Quoted 3 lines
drivers/acpi/scan.c +3 -0
+               if (error == -EPERM)
+                       return ACPI_OST_SC_EJECT_NOT_SUPPORTED;
+               else if (error == -EBUSY)

Redundant else...

You are right, I will remove it.

Quoted 10 lines
Quoted 1 line

+ return ACPI_OST_SC_DEVICE_BUSY;

Perhaps switch case here as well?
switch (error) {

 case -EPERM;
   return X;
 case -EBUSY:
   return Y;
}

I want to use the event source as the target of switch because different event source has different ost_src definition. If I add the support of insertion event then the code will be like this:

static int acpi_ost_status_code(u32 src, int error)

{
        switch (src) {
        case ACPI_NOTIFY_EJECT_REQUEST:
        case ACPI_OST_EC_OSPM_EJECT:
                if (error == -EPERM)
                        return ACPI_OST_SC_EJECT_NOT_SUPPORTED;
                if (error == -EBUSY)
                        return ACPI_OST_SC_DEVICE_BUSY;
                break;
        case ACPI_OST_EC_OSPM_INSERTION:
                if (error == -EPERM)
                        return ACPI_OST_SC_INSERT_NOT_SUPPORTED;
                if (error == -EBUSY)
                        return ACPI_OST_SC_INSERT_IN_PROGRESS;
                break;
        }
        return error ? ACPI_OST_SC_NON_SPECIFIC_FAILURE : ACPI_OST_SC_SUCCESS;
}

The ACPI_OST_EC_OSPM_INSERTION represents "Insertion Processing (Source Event: 0x200)" that it has different ost code definition. Just we didn't support it in kernel (maybe just didn't see any machine used it).

Quoted 11 lines

drivers/acpi/scan.c static int acpi_generic_hotplug_event(struct acpi_device *adev, u32 type)

Quoted 8 lines
drivers/acpi/scan.c +5 -0
+               break;
+       }
+       return error ? ACPI_OST_SC_NON_SPECIFIC_FAILURE : ACPI_OST_SC_SUCCESS;
+}
 
 
+       ost_code = acpi_ost_status_code(src, error);
  err_out:

I guess you need to swap those lines.

Do you mean move the "err_out:" to the position before acpi_ost_status_code()? The err_out tag used by the validation checking of acpi handler that it wants to jump to evaluate _OST:

void acpi_device_hotplug(struct acpi_device *adev, u32 src)

{
        u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
        int error = -ENODEV;

        lock_device_hotplug();
        mutex_lock(&acpi_scan_lock);

	/*
	 * The device object's ACPI handle cannot become invalid as long as we
	 * are holding acpi_scan_lock, but it might have become invalid before
	 * that lock was acquired.
	 */
	if (adev->handle == INVALID_ACPI_HANDLE)
		goto err_out;
	[...snip]
Quoted 3 lines
Quoted 2 lines
  err_out:
        acpi_evaluate_ost(adev->handle, src, ost_code, NULL);

Thanks a lot!
Joey Lee